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Browse Prior Art Database

Slave Line Power Switching of System Peripherals

IP.com Disclosure Number: IPCOM000102303D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Sawdon, D: AUTHOR

Abstract

Small computer systems which contain multiple self-powered units, such as monitors and printers, result in the user being presented with many separated power switches. Confusion and potential reliability problems result if some devices are not switched off. There is a need for single power-switch operation in certain areas. This disclosure describes ways of reducing the quantity of line switches by sensing the current flow in one power cord and switching the power of slave devices in sympathy. A method of current sensing without intrusive connection to the sensed mains cord is included.

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This is the abbreviated version, containing approximately 63% of the total text.

Slave Line Power Switching of System Peripherals

       Small computer systems which contain multiple
self-powered units, such as monitors and printers, result in the user
being presented with many separated power switches. Confusion and
potential reliability problems result if some devices are not
switched off.  There is a need for single power-switch operation in
certain areas.  This disclosure describes ways of reducing the
quantity of line switches by sensing the current flow in one power
cord and switching the power of slave devices in sympathy.  A method
of current sensing without intrusive connection to the sensed mains
cord is included.

      Many personal systems, such as the PC1 and PC X/T systems,
provide one switched power outlet.  The PS/55 systems provide a
signal voltage to the PS/55 monitors in the signal interface, which
enables the monitor power supply.  Many systems without built-in
single power switching could achieve it in the following way. If
current in the master device line cord is sensed by monitoring
circuits within a slave device, power can be switched to the slave
device when a current is detected in the master cord.

      There are several possible implementations of master cord
sensing.  The simplest is to pass one conductor of the master line
cord through a relay winding; the relay contacts are then used to
switch power to the slave.

      An alternative is to sense the magnetic field around the master
line cord.  T...