Note: Descriptions are shown in the official language in which they were submitted.
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PLUG
BACKGROUND OF THE INVENTION
1. ~IELD OF THE INVENTION
The present invention re]ates to a plug to be connected with a
socket.
2. DESCRIPTION OF THE RELATED ART
In case the plug to which this invention pertains is an electric plug,
it sometimes happens that the electric plug is inadvertently disconnected
from an electric outlet socket e.g. when a cord connected with the plug is
strongly pulled by being hooked by a foot of a person who has accidentally
tripped over the cord. The disconnection results in power failure which in
turn causes various problems iIl the electric appliances which were
connected to the socket. For instance, if the appliance incorporates a timer,
an error will result in a time set on this timer. In the case of a temperature
controller for controlling water temperature in a tank for tropical fish kept
therein, the failure may lead to killing of the fish. Or, in the case of a
computer, this may result in total destruction of data being processed on the
computer.
In order to cope with this problem, some electric appliances are
provided with power-failure protection means such as a backup battery
incorporated therein for avoiding sudden stop of electricity supply.
However, due to ~ignific~nt cost burden therefrom, use of such protection
means has been limited to rather expensive appliances, hardly used in less
expensive appliances widely used in domestic and business environment.
The present invention attends to the above-described state of the
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art and its primary object is to propose more economical, yet effective means
for avoiding inconveniences resulting from a power failure by providing an
electric plug which can effectively resist accidental disconnection thereof
from an electric socket such as a common AC wall outlet.
SUMMARY OF THE INVENTION
For accomplishing the above-noted object, a plug, according to the
present invention, comprises:
a plug terminal to be inserl;ed into and connected with a socket;
an anti-disconnection member provided to the plug terminal; and
a switch me(~h~qni~m for swit~hing over between a first position
where the anti-disconnection member is retracted within the plug terminal
and a second position where the anti-disconnection member is projected out
16 oftheplugterminal.
With the above construction, the anti-disconnection member is
normally retracted and kept inside the plug terminal. When the plug is
connected with the socket, the switch mech~ni~m is operated to bring the
anti-disconnection member into the second position where this member is
20 projected out of the terminal. Then, the projection of the anti-disconnectioneffectively resists inadvertent dis~onnection of the plug from the socket
when the plug is accidentally pulled therefrom.
Preferably, the plug includes a plurality of said second positions.
The mating socket may come in a variety of inner constructions.
26 Then, the above feature may provide the plug with adaptability for such
varied constructions.
According to another preferred feature of the invention, the plug
includes a pair of said plug terminals and a corresponding pair of anti-
disconnection members; and the switch me~h~ni~m includes a single drive
30 member for commonly driving the pair of anti-disconnection members.
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The use of one common drive member, rather than two members, allows
reduction in the number of components, hence, the cost of the plug.
Incidentally, the plug of the invention may be any kind of plug, not
limited to any specific electric plug of some particular electric appliance.
According to a still further feature of the invention, the plug further
comprises an urging member for urging the anti-disconnection member
from the second position to the first position; the anti-disconnection
member includes a guide portion for guiding the movement of the anti-
disconnection member from the second position to the first position when
the anti-disconnection member is forcibly driven from the second position to
the first position; and the anti-disconnection member is switched over to the
second position upon completion of insertion of the plug into the socket.
In the case of the above construction, the anti-disconnection
member is normally kept at the second position where the member projects
out of the plug terminal. Then, as the plug is inserted into the socket, the
anti-disconnection member is forcibly moved from this second projecting
position to the first retracted position. Thereafter, when the plug has been
completely inserted into the socket, the anti-disconnection member is
automatically returned to the second position from the first position by the
urging force of the urging member.
Therefore, if the plug is provided with the above construction, a
user may insert this plug into the socket in the same manner as the
conventional plug without the anti-disconnection member. Then, the
invention has achieved the useful plug having the anti-disconnection
function without losing the convenience of the conventional plugs having no
such function.
The urging member may be constructed in a variety of manners.
For instance, the member may be constructed from a wire. The wire
member has the advantages of readiness of manufacture and possibility of
the member being readily disposed within such a limited space as the inside
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of the plug terminal.
According to a still further feature of the invention, the plug
includes a pair of said plug terminals and a corresponding pair of said anti-
disconnection members; and the second positions of these members are
arranged such that they are projected in direction opposed to each other.
In the case of some known types of sockets, they are to be inserted
while being turned. Then, when such plug is inserted into the socket, the
plug may be inadvertently disconnected from the socket, if the anti-
disconnection members are projected in a same direction.
However, if the anti-disconnection members are caused to project
in the direction opposite to each other, as so proposed by the present
invention, it may be assured that either one of the members may reliably
stay engaged with the socket. Therefore, with this construction, the plug
may provide its effect in such special case also.
According to one preferred embodiment, the anti-disconnection
member is constructed as a lever pivotable about a pivot axis provided in
the plug terminal. For disconnecting the plug from the socket, a
manipulator member provided to a cover of the plug is manipulated for
moving the anti-disconnection member from the second projecting position
to the first retracted position. In doing this, the presence of the pivot in theplug terminal may render the operation more smooth and easier.
BRIEF DESCRIPTION OF THE DRAVVINGS
Further and other features and objects of the invention will become
apparent from the following detailed disclosure of preferred embodiments in
conjunction with accompanying drawings, in which;
Fig. 1 is a perspective view showing an entire electric plug relating
to a first preferred embodiment of the invention, with (a) showing a
condition when anti-disconnection levers are retracted and (b) showing a
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further condition when the anti-disconnection levers are projected,
respectively,
Fig. 2 is a plan view showing a switch meçhz~ni~m relating to the
first embodiment,
Fig. 3 is a side view showing the switch mechanism relating to the
first embodiment,
Fig. 4 is a section view showing a condition when the plug of the
first embodiment is connected with a socket,
Fig. 5 is a section view showing a further condition when the plug
of the first embodiment is connected with the socket,
Fig. 6 is an exploded perspective view showing plug terminals
relating to the first embodiment,
Fig. 7 is a perspective view showing an entire electric plug relating
to a second embodiment of the invention,
Fig. 8 is a side view showing a switch mech~ni~m relating to the
second embodiment,
Fig. 9 is a plan view showing the switch me~h?~ni.~m relating to the
second embodiment,
Fig. 10 is a perspective view showing an entire electric plug
relating to a third preferred embodiment of the invention, with (a) showing
a condition when anti-disconnection levers are retracted and (b) showing a
further condition when the anti-disconnection levers are projected,
respectively,
Fig. 11 is a section view showing a switch me~h~ni.cm relating to
the third embodiment, with (a) showing a condition when a push button is
depressed to retract the anti-disconnection levers and (b) showing a further
condition when the push button is released to project the anti-disconnection
levers,
Fig. 12 is an exploded perspective view showing plug terminals
relating to the third embodiment, and
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Fig. 13 is a view illustrating a process for inserting the plug of the
third embodiment into the socket.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[first embodiment]
A first preferred embodiment of the present invention will now be
detailed with reference to Figs. 1 through 6.
An electric plug 1 includes a pair of plug terminals 2a, 2b, covers 3,
4, a screw 5 for fixedly connecting the covers 3, 4 together, and a cord 6.
As shown in Fig. 6, the plug terminals 2 include outer elements 20,
21, and an intermediate element 22 interposed between the outer elements
20, 21. The intermediate element 22 defines a cutout 22a for forming a
space A in which an anti-disconnection me~h~ni.~m is to be attached.
These element, i.e. the outer elements 20, 21 and the intermediate element
22 are connected together by any known appropriate method such as
welding, bonding or the like. In the space A, there is attached an anti-
disconnection lever 11 ('an anti-disconnection member') which is pivotable
about a shaft 12. The shaft 12 is attached to the outer elements 20, 21 by
any appropriate method such as welding, caulking or the like. This anti-
disconnection lever 11 includes a serrated portion 11a for coming into
contact with the inside of the socket for providing an anti-disconnection
function for the plug connected thereto and a gear-teeth portion 11b for
meshing with a rack portion 10a of a drive member 10. The serrated
portion 11a is shaped such that each tooth thereof forms an angle H =45
degrees, as shown in Fig. 3.
Further, to the cover 3, there is mounted a manipulator lever 8
which is slidable along an axis Y-Y in Fig. 3 for activating the anti-
disconnection lever 11 via the drive member 10. The manipulator lever 8
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includes a control portion 8a to be manipulated by a user's finger and a
pressing portion 8b for driving the drive member 10. A spring 9 is provided
for biasing the manipulator lever 8 in the upward direction in Fig. 8 This
spring 9 has one leg thereof supported by a connecting portion lOb of the
5 drive member 10 and the other leg thereof supported by a fixing portion 3a
of the cover 3.
The drive member 10 includes a pair of rack portions 10a in
correspondence with a pair of plug terminals 2a, 2b and an interconnecting
portion 10b for interconnecting these rack portions 10a. Then, by driving
10 the drive member 10 in the downward direction in Fig. 2, the pair of right
and left anti-disconnection levers 11 may be driven simultaneously. The
drive member is formed of non-conductive material such as synthetic resin,
in order to avoid short-circuit.
The manipulator lever 8 is pivotable about the axis Y-Y in Fig. 2.
15 For operating this lever 8, the control portion 8a will be pivotally raised by
the finger and then this portion 8a is pressed downwards. The cover 3
defines a slot 7 for guiding the manipulator lever 8. And, this slot 7
includes a plurality of hol(ling portions 7a, 7b, 7c at each of which the
control portion 8a may be stably held in position. By selectively hokling
20 the control portion at one of the holding portions 7a, 7b, 7c, the pivotal
amount of the anti-disconnection lever, i.e. the projecting amount thereof
from the plug terminal 2, may be varied.
The position where the control portion 8a is held at the holding
portion 7a corresponds to 'a first position' and the position where the portion
25 8a is held at the hol(ling portion 8b or 8c corresponds to 'a second position',
respectively.
(description of operation)
Next, the operation of the above-described plug relating to the first
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embodiment will be described.
First, the plug 1 is inserted into a socket 13; then, the manipulator
lever 8 is operated for ret~ining the control portion 8a thereof at either the
portion 7b or 7c. Which of these portions 7b, 7c the portion 8a is to be held
5 will be determined, depending on the particular inner construction of the
socket 13. When the control portion 8a is held at the holding portion 7c,
the anti-disconnection levers 11 are pivoted through 90 degrees
approximately, thus subst~nti~lly forming 90 degrees relative to the
respective plug terminals 2, as shown in Fig. 4.
Conversely, for disconnecting the plug 1 from the socket 13, this
becomes possible after returning the anti-disconnection levers 11 from the
condition of Fig. 4 to the condition of Fig. 3. Specifically, the manipulator
lever 8 is operated so as to allow the control portion 8a to exit the hollling
portion 7c. Upon this, by means of the biasing force of the spring 9, the
15 manipulator lever 8 will be autom~tic~lly returned to its original position so
as to bring its control portion 8a to the position of the holding position 7a.
Thereafter, in order to complete this disconnecting operation, the
manipulator lever 8 is operated again so as to allow the control portion 8a to
be held at the holding portion 7a in the stable manner.
[second embodiment]
A second embodiment of the invention will be described next with
reference to Figs. 7 through 9. Fig. 7 shows an outer appearance of a plug
25 relating to this second embodiment, with (a) showing the plug as viewed
from the side of its plug terminals and (b) being a plan view showing cases
from above. Fig. 8 is a side view of a switch me~h~ni~m relating to this
second embodiment, and Fig. 9 is a plan view of the switch me~h~ni~m
The components employed in this embodiment and functioning similarly to
30 those employed in the first embodiment are denoted with like reference
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marks or numerals.
This plug 1 ~ ers in its outer appearance from that of the first
embodiment in that the cord 6 and the plug terminals 2 extend normal to
each other and in correspondence therewith the covers 3, 4 have a different
5 shape than those of the first embodiment. As shown in Figs. 8 and 9, the
cover 3 defines a through hole 3a through which a manipulator knob 14
extends. This manipulator knob 14 includes a female thread portion 14b
which is threaded with a male thread portion formed on the interconnecting
portion 10b of the drive member 10.
Then, after inserting this plug 10 into the socket, as the
manipulator knob 14 is progressively turned, the threading action of this
knob moves he drive member 10 to the left side in Fig. 8 thereby causing the
anti-disconnection levers 11 to project from the respective plug terminals 2.
Conversely, for disconnecting the plug 1 from the socket, the manipulator
15 knob 14 is reversely turned to cause the anti-disconnection levers 11 to be
accommodated within the respective plug terminals 2.
Some of modified constructions of the above-described
embodiments will be described nexl,.
In the first embodiment, the specific number of the holding portions
20 provided in the slot 7 is not limited to that described in the embodiment.
The number may be decreased or increased, depending on the convenience.
In the first and second embodiments, the shape of the portion of the
anti-disconnection lever 11 which portion comes into engagement with the
inside of the socket is not limited to the serrated shape, but may vary in any
25 other manner as long as such shape provides the function of inhibiting
inadvertent disconnection of the plug from the socket.
[third embodiment]
A third embodiment of the invention will be described next, with
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reference to Figs. 10 through 13. Fig. 10 shows an entire outer appearance
of a plug relating to this embodiment, with (a) showing a condition of the
plug when a press button 32 has been depressed to allow accommodation of
the anti-disconnection levers, (b) showing a further condition when the
5 button has been released to allow projection of the anti-disconnection levers.Fig. 11 shows a switch me~h~ni.qm, with (a) showing the me~h~niqm in
section after completion of insertion of the plug into the socket, (b)
illustrating a process of inserting the plug into the socket, respectively. Fig.12 is a plan view of the plug, and Fig. 13 is an exploded perspective view of
10 plug terminals.
The plug 1 includes a pair of plug terminals 41, 42, covers 3, 4, and
a screw 5 for interconnecting the covers 3, 4, a cord 6 and anti-disconnection
levers 30, 31 as the anti-disconnection members.
The anti-disconnection levers 30, 31 are provided for the respective
plug terminals 41, 42. And, as may be apparent from Fig. 10, these levers
30, 31 are adapted to project in opposite directions from the end faces of the
respective plug terminals 41, 42.
Figs. 11 through 13 show t;he switch me~h~ni.qm in greater details.
Although the anti-disconnection levers 30, 31 project in the opposite
20 directions from each other as described above, these levers are identical in
the function. Thus, only one of them will be detailed.
The plug terminal 41 is comprised essentially of a first terminal
member 43 and a second terminal member 44, with these members being
connected with each other via an appropriate method such as welding. The
25 first terminal member 43 defines a space 41c for accommodating the anti-
disconnection lever 30 and a spring 36 which functions as a biasing
element. Further, to these respective members 43, 44, there are integrally
formed dowel-like support shafts 41a, 41b for pivotally supporting the anti-
disconnection levers 30. Preferably, the first terminal member 43 is
30 formed by die-casting, while the second terminal member 44 is formed by
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press.
The anti-disconnection lever 30 will be described in greater details
with reference to Fig. 1. This lever 30 includes a shaft bore 30a in which
the support shaft 41a, 41b is fitted, a guide portion 30b to be pressed into
5 the hole of the socket when the plug 1 is inserted into the socket for causingthe anti-disconnection lever 30 about the pivot shaft 41a, 41b, a stopper face
30c functioning to prevent disconnection of the plug 1 upon completion of
the insertion of the plug 1 into the socket, an operating surface on which the
wire spring 35 acts, and a press-but;ton operating face 30e against which the
10 press button 32 is depressed.
As the pivot shafts 41a, 41b are disposed inside the plug terminals
41, 42 away from the position of the press button 32, the press bottom 32
may be operated with good feel.
The guide portion 30b has an inclination of 30 to 43 degrees
15 approximately relative to the longil;udinal direction of the plug terminal 41,
such that this guide portion forces the anti-disconnection lever 30 when the
plug 1 is inserted into the socket. Preferably, the wire spring 35 is formed
by cutting a wire material such as a piano wire. This wire spring may have
any appropriately selected cross section, such as of circular, rectangular
20 shape or the like.
The press button 32 includes a press portion 32a to be depressed by
a finger or a thumb and a press seat 32b which acts on the button operating
face 30e of the anti-disconnection lever 30. As shown in Fig. 12, the center
of the press button 32 is offset from the anti-disconnection lever 30, so that
25 the press seat 32b has an oval shape. Further, as shown in Fig. 11, since
the two anti-disconnection levers 30, 31 project in the opposite directions,
another press button 33 is provided on the other opposite side.
(function of the construction of third embodiment)
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Next, the function of this plug 1 when it is inserted into the socket
will be described.
As illustrated in Fig. ll(b), when this plug 1 is inserted into the
socket in the same manner as the conventional plug, an end face lla of the
5 hole of the socket 11 presses the guide portions 30b of the pair of anti-
disconnection levers 30, 31, whereby the anti-disconnection levers 30, 31 are
forcibly pivoted against the biasing force of the wire springs 36, that is, the
anti-disconnection levers 30, 31 are moved from the projecting position
toward the storage position. Accordingly, when the plug is inserted into
10 the socket, it is not necessary to depress the press buttons 32, 33.
As shown in Fig. ll(a), upon completion of the insertion of the plug
1, the guide portions 30b are released from the end face lla, so that the
anti-disconnection levers 30, 31 are returned to the respective projecting
positions by the biasing force of the wire springs 35, whereby the stopper
15 faces 30c are retained to a back face llb of the socket 11. As a result, the
plug 1 is prevented from being inadvertently disconnected from the socket
11.
Although the present invention has been described with reference
20 some particular embodiments, it is to be understood that these
embodiments are merely illustrative of the application of the principles of
the invention. Numerous modifications may be made therein and other
arrangements may be devised without departing from the spirit and scope
of the invention.
12
