Electrical transmission or interconnection systems – Plural supply circuits or sources – Connecting or disconnecting
Reexamination Certificate
2000-01-26
2001-07-10
Jackson, Stephen W. (Department: 2836)
Electrical transmission or interconnection systems
Plural supply circuits or sources
Connecting or disconnecting
C307S044000, C307S066000
Reexamination Certificate
active
06259171
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a switching device. More specifically, it relates to a hot-swap device allowing on-line switching of the power source of a system without causing the system to crash.
2. Description of the Related Art
A relay is a popular switching devices applied to perform switching operation. However, the relay can not perform a switching operation without introducing a time delay because of its mechanism and structure. Therefore, electronic systems using relays for switching operation may crash due to the switching delay of the relays. For example, using a relay to switch one battery set to the other battery set supplying power to a notebook computer could make the notebook computer crash.
FIG. 1
schematically shows a conventional swapping circuit for switching two battery sets installed in a notebook computer. Referring to
FIG. 1
, one of the two batter sets
12
and
14
is selected by a relay
10
to supply power to a notebook computer
16
. For example, the battery set
12
first supplies power to the notebook computer
16
. When the battery set
12
is going to run out of its power and users want to replace the battery set
12
with a new one without shutting down the notebook computer
16
, the power supplied to the notebook computer
16
is swapped form the battery set
12
to the battery set
14
via the control of the relay
10
. Then users can take out the battery set
12
and install a new one. When the relay
10
performs the switching operation, the metal rod or slice
10
P (in
FIG. 1
) moves from the terminal A to the terminal B so that the notebook computer
16
obtains power from the battery set
14
instead of the battery set
12
. However, the metal rod or slice
10
P does not move from terminal A to terminal B instantly; some switching delay is inevitable. Therefore, the notebook computer
16
does not obtain steady power during the period when the metal rod or slice
10
P moves from terminal A to terminal B. Accordingly, the notebook computer may crash. Moreover, the more aged the relay
10
, the longer the switching delay is, and the possibility of the notebook computer crashing is increased.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a hot-swap device that prevents a system having two power sources from crashing when performing power swapping operation between the two power sources by continuously providing spare-power to the system during the switching period.
The present invention achieves the above-indicated objects by providing a hot-swap device comprising: a selection device for selecting a first power source or a second power source to feed power to the system; and a spare-power generating device for continuously feeding spare power to the system during the period when the selection device cuts the connection from the first power source to the system and before the selection device feeds the second power source to the system.
REFERENCES:
patent: 5278453 (1994-01-01), Pollmeier
patent: 5739596 (1998-04-01), Takizawa et al.
patent: 5894413 (1999-04-01), Ferguson
patent: 5939801 (1999-08-01), Bouffard et al.
patent: 6034508 (2000-03-01), Chang
Darby & Darby
Jackson Stephen W.
Mitac International Corp.
Polk Sharon
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