Electrical connectors – Metallic connector or contact having movable or resilient... – Spring actuated or resilient securing part
Reexamination Certificate
2001-12-27
2004-03-30
Gilman, Alexander (Department: 2833)
Electrical connectors
Metallic connector or contact having movable or resilient...
Spring actuated or resilient securing part
C439S834000, C439S441000
Reexamination Certificate
active
06712649
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plug structure for connecting a pair of lead wires comprising a signal wire and a ground wire to an apparatus such as an audio apparatus.
2. Description of the Related Art
In an apparatus employing a lead wire for wiring, for example, an audio apparatus, an amplifier and a speaker are connected to each other by a pair of lead wires comprising a signal wire and a ground wire. Connection between a lead wire and such an apparatus is usually established as follows. As shown in
FIG. 11
, a lead wire is, at its skinned end, connected to a connector, called a lever terminal
103
, attached to a terminal plate
101
provided on the back-surface side of the apparatus.
That is, a lever
105
is rotated in a clockwise direction viewing the figure against a force of a torsion spring
107
, and a skinned end of a lead wire
109
is inserted into an insertion hole
111
of the lever terminal
103
. Upon a return of the lever
105
to its original position, the lead wire
109
is caught in between a metal contactor
113
, which is formed integrally with the lever
105
, and a metal contactor
117
formed inside a housing
115
of the lever terminal
103
, and is thereby connected to the metal contactor
117
.
However, modem audio apparatuses, in contrast to conventional ones having a 2-channel system, have come to have a 4- or 6-channel system, i.e. require a larger number of speakers. This requires that the lead wire
109
, formed by using a signal and a ground wire in combination, be separately connected to each of the speakers. Consequently, as shown in
FIG. 12
, the terminal plate
101
on the back-surface side of the amplifier is provided with a multiplicity of lever terminals
103
arranged in line.
Workers find difficulty in performing connection operations in the terminal plate
101
on the back surface of the amplifier, because the visibility of the work area is poor from the worker position. It is also extremely difficult to connect a multiplicity of lead wires
109
to their respective lever terminals
103
without fail.
Due to the difficulty of the connection operations, the lead wire
109
cannot be connected to the terminal with its skinned portions kept in a deeply-inserted state. Consequently, adjacent portions are brought into contact with each other, causing short circuits. Moreover, due to the poor visibility of the work area, the signal and ground wires, although they are usually distinguished from each other by their skin colors (red and black), might be inadvertently connected to reverse positions.
To overcome such inconveniences, a connection method as shown in
FIG. 13
has been proposed that employs a plug
125
. Specifically, a signal wire
121
and a ground wire
123
, used in pairs as a lead wire
109
, are attached to the plug
125
, and this plug
125
is inserted into a socket
127
provided on an amplifier side.
That is, the end of each of the lead wires
121
and
123
is fixed in advance to its respective metal-made connector terminal
129
. The connector terminal
129
is barrel-shaped, and its rear-end portion (left-end portion viewing the figure) has a U-shaped section. Upon insertion of the skinned end of the lead wire
109
, the barrel is subjected to caulking, thereby fixing the lead wire
109
to the connector terminal
129
. The connector terminal
129
has its substantially cylindrical front-end portion formed as a contact terminal
133
, into which a pin terminal acting as an amplifier-side terminal
131
is inserted so as to be in contact therewith. These two connector terminals
129
with the lead wires
109
fixed thereto are received in their respective housing portions
135
formed in a single plug
125
so as to be retained.
Formed in a terminal plate
137
disposed on the back surface of the amplifier is a connection recess
139
constituting the socket
127
which is engaged with the plugs
125
. Two apparatus-side terminals, or pin terminals
131
, are formed inside the connection recess
139
protruding therein, these corresponding to the signal wire
121
and the ground wire
123
, respectively.
To prevent the plug
125
from being inserted in a 180-degree inverted position, the connection recess
139
has a rib
141
formed on its inner side along the insertion direction so as to be protruded, and the plug
125
has, on its outer surface, a groove
143
which receives the rib
141
. The plug
125
and its corresponding socket
127
have the same skin color.
In the connector shown in
FIG. 13
,
(1) By providing the concave groove
143
and the rib
141
for the plug
125
and the socket
127
, respectively, the plug
125
can be inserted in a proper position, thereby preventing the signal and ground wires from being connected in reversed polarity.
(2) By giving the plug
125
and its respective socket
127
the same skin color, the lead wire
109
can be connected to the speakers for a multi-channel system with no possibility of wrong wiring.
(3) Since the skinned portion of the lead wire
109
is not exposed, adjacent lead wires
109
do not make contact with each other. Consequently, short circuits can be prevented.
(4) In this connector, unlike the lever terminal
103
shown in
FIG. 111
which requires two operations: rotation of the lever
105
; and insertion of the lead wire
109
, the connection operation can be completed simply by inserting the plug
125
. Therefore, even though the back surface of the amplifier is not exposed to the worker view, the connection operation can be easily achieved with one hand.
However, the connector shown in
FIG. 13
lacks versatility. For example, in a case where an audio enthusiast tries to connect a specially-designed thick lead wire to the speaker, whereas the lever terminal
103
shown in
FIG. 11
conforms to such a requirement, the connector in question is unusable. That is, only the lead wire
109
attached in advance to the plug
125
may be acceptable.
To achieve both of the convenience of the plug
125
shown in FIG.
13
and the versatility of the lever terminal
103
shown in
FIG. 11
, two types of connectors, i.e. the socket
127
and the lever terminal
103
, need to be provided in a single back-surface panel of an amplifier or the like. This leads to an undesirable increase in the number of constituent components, causing space shortage in the back-surface panel.
The above description deals only with problems associated with connection between an amplifier and a lead wire provided in a speaker. However, similar problems tend to occur when a lead wire, realized by using a signal and a ground wire in combination, is connected between another device constituting an acoustic or other apparatus.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention solves the above-described problems, and accordingly its object is to provide a plug that prevents reverse insertion of a signal and a ground wire arranged in pairs, prevents occurrence of short circuits in adjacent lead wires, facilitates connection of the lead wires, and allows connection of lead wires of any other type, i.e. offers versatility.
To achieve the above object, according to a first aspect of the present invention, a plug for connecting a pair of lead wire comprising a first lead wire and a second lead wire to an apparatus, comprising:
a plug housing configured so as to be insertable into and withdrawable from a connection recess provided on an apparatus side;
a pair of plug-side contact terminals disposed inside the plug housing, the plug-side contact terminals being contacted by a pair of apparatus-side terminals corresponding to the first and second lead wires;
reverse insertion preventive means for providing the plug housing with an asymmetrical profile so that it is inserted into and withdrawn from the asymmetrically-configured connection recess only in a predetermined position; and
connecting means for connecting a pair of plug-side contact terminals to the first and second lead wires, respectively,
the connecting means being
Mano Nobuyuki
Matsuda Takeshi
Nozaki Fumio
Gilman Alexander
SMK Corporation
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