Electrical transmission or interconnection systems – Plural supply circuits or sources – Connecting or disconnecting
Reexamination Certificate
1999-09-20
2001-09-04
Ballato, Josie (Department: 2836)
Electrical transmission or interconnection systems
Plural supply circuits or sources
Connecting or disconnecting
C307S043000
Reexamination Certificate
active
06285092
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cable apparatus for supplying power from an electronic apparatus to another electronic apparatus, and more particularly, to a cable apparatus for use in connecting a personal computer (will be referred to simply as “PC” hereinafter) to it associated peripheral devices.
2. Description of the Related Art
Generally, the computer system of a PC is configured such that the PC and its associated peripheral devices are connected to each other by a cable apparatus such as a power line via an interface for each of the peripheral devices. The computer system uses a display, keyboard, mouse, printer, modem, etc. as the peripheral devices. Recently, the video camera, electronic still camera and the like have been added to the above-mentioned PC-oriented peripheral devices. Namely, more and more kinds of peripheral devices are used with a PC.
The cable apparatus comprises a cable and a plug connected integrally to either end of the cable. It serves as a transmission path to convey a power and the like from a PC to each peripheral device.
For connection between the PC and each of its associated peripheral devices via the cable apparatus in a computer system, the PC is provided on its enclosure with many connecting terminals such as an analog RGB terminal, digital RGB terminal, etc.
Along with the increase in kind of the above-mentioned peripheral devices and improvement in PC performance in these years, cable apparatuses have been proposed for which plugs and receptacles have been standardized in shape as in the IEEE 1394 high-performance serial bus (will be referred to as “IEEE 1394” hereinafter) for connection of a variety of peripheral devices to a PC via a single interface.
The cable apparatus in conformity with the IEEE 1394 standard has been proposed for a compact design, lower cost, high versatility, etc. It comprises a cable having a power line, etc. and a small plug integrally secured to either end of the cable and having six terminals.
Namely, the cable apparatus conforming to the IEEE 1394 standard can connect power from a PC directly to its associated peripheral devices since it incorporates a power line.
Also, the interface according to the IEEE 1394 standard is characterized in that it can connect a plurality of peripheral devices to a PC and the cable can be connected to, and disconnected from, each of the peripheral devices while the latter is being energized and in operation, that is, in a hot status.
Next, a conventional cable apparatus will be described herebelow with reference to the accompanying drawings:
Referring now to
FIG. 1
, there is schematically illustrated in the fon-n of a block diagram a conventional cable apparatus adapted to supply both an internal power and an external power. Also,
FIGS. 2A and 2B
show schematic block diagrams of conventional cable apparatuses, one adapted to supply only an internal power (as in
FIG. 2A
) and the other adapted to supply only an external power (as in FIG.
2
B).
In
FIG. 1
, the conventional cable apparatus is generally indicated with a reference
120
. The cable apparatus
120
comprises a power supply unit
121
, Schottky diode
122
, fuses
123
,
124
and
125
, and connectors
126
,
127
and
128
.
In the cable apparatus
120
, the connectors,
126
,
127
and
127
should desirably have a high impedance in relation to each other so that they will not influence each other. To supply and receive an external power between these connectors in case no internal power is supplied but the external power is supplied, however, the cable apparatus
120
is constructed as shown in FIG.
1
. To pass a current only when the internal power is supplied but no current when no internal power is supplied, the Schottky diode
122
is provided for each bus so that the power supply side works as an anode while each bus works as a cathode.
In the cable apparatus
120
, the power supply unit
121
supplies an internal power as will be described below:
As shown in
FIG. 1
, the power supply unit
121
supplies an internal power through the Schottky diode
122
to the connector
126
via the fuse
123
, connector
127
via the fuse
124
, and to the connector
128
via the fuse
125
, respectively.
Next, the power supply unit
121
which does not supply internal power, namely, in which an external power is supplied from the connectors, will be described below:
At least one (connector
126
,
127
,
128
for example) of the connectors
126
supplies the external power to the connector
127
via the fuses
123
and
124
, and to the connector
128
via the fuse's
123
and
125
, respectively.
The connectors
127
and
128
supply the external power to other connectors in the same manner as the connector
126
. The external power may be supplied to more than one of the connectors
126
to
128
. When no internal power is supplied, the connectors supply and receive an external power between them as in the above.
In
FIG. 2A
, the convention cable apparatus is generally indicated with a reference
130
. The cable apparatus
130
comprises a power supply unit
131
, fuse
132
, Schottky diodes
133
,
134
and
135
, and connectors
136
,
137
and
138
.
In the cable apparatus
130
, each of the connectors
136
to
138
has a higher impedance than the others. That is, the cable apparatus
130
is an ideal one in which an internal power can be supplied at a higher impedance at one of the connectors than the others.
In the cable apparatus
130
, the power supply unit
131
supplies an internal power as will be described below:
As shown in
FIG. 2A
, the power supply unit
131
supplies an internal power to the connector
136
via the fuse
132
and Schottky diode
133
, connector
137
via the fuse
132
and Schottky diode
134
and to the connector
138
via the fuse
132
and Schottky diode
135
, respectively.
However, when the power supply unit
131
supplies no internal power but an external power is supplied at the connectors
136
,
137
and
138
, the power will not flow from the connectors
136
,
137
and
138
to the fuse
132
because of the Schottky diodes
133
,
134
and
135
, so that the connectors
136
,
137
and
138
cannot supply and receive the external power between them.
Therefore, in the cable apparatus
130
, the connectors cannot supply any external power to one another.
Finally, a cable apparatus having no internal power source, namely, in which an external power is supplied from the connectors of the cable apparatus, will be described below:
In
FIG. 2B
, the conventional cable apparatus is generally indicated with a reference
140
. The cable apparatus
140
comprises fuses
141
and
142
and connectors
143
,
144
and
145
.
In this conventional cable apparatus
140
, at least one (connector
143
for example) of the connectors
143
to
145
can supply an external power to the connector
144
via the fuse
141
, and to the connector
145
via the fuses
141
and
142
, as shown in FIG.
2
B.
The connectors
144
and
145
supply the external power to other connectors in the same manner as the connector
143
. The external power may be supplied to more than one of the connectors
143
to
145
. Thus in this cable apparatus
140
, no internal power can be supplied but the connectors
144
to
145
can supply and receive an external power between them.
Since in the cable apparatus
140
, the connectors
143
to
145
are connected to each other by means of fuses
141
and
142
, respectively, when an external power is supplied to the connectors
143
,
144
and
145
, it can be supplied and received between the connectors and delivered from them to outside.
However, the conventional cable apparatuses do not strictly meet the requirements for power supply prescribed in the interface standard. In many of the conventional cable apparatuses, priority is given to reception of an external power. Thus, the conventional cable apparatuses are disadvantageous in that when an internal power is supplied, each bus will not have a h
Hagimori Masashige
Kawahara Hirokazu
Ballato Josie
Maioli Jay H.
Polk Sharon
Sony Corporation
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