Browse Prior Art Database

Delayed Power Switching Method

IP.com Disclosure Number: IPCOM000105251D
Original Publication Date: 1993-Jul-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Hanabusa, H: AUTHOR [+2]

Abstract

Disclosed is a feature for reliable power-off switching control of the personal computer with an internal ink jet printer by the slave micro computer unit (SMCU). Power-off switching control is one of SMCU's functions and is required to be top priority from the safety point of view.

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This is the abbreviated version, containing approximately 97% of the total text.

Delayed Power Switching Method

      Disclosed is a feature for reliable power-off switching control
of the personal computer with an internal ink jet printer by the
slave micro computer unit (SMCU).  Power-off switching control is one
of SMCU's functions and is required to be top priority from the
safety point of view.

      The PC with an internal ink jet printer needs delayed power-off
switching because the printer head is required to be capped in order
to prevent it from dry when the PC power is turned off.  As the SMCU
has no mechanism of the watchdog timer, a mechanism for self error
detection if the SMCU is out of control, the power-off control module
should be executed even if the other modules are in trouble.  In
other words, the power-off control module should work independently
of the other modules.

      Using a reset signal, which is generated at power switch off,
to the SMCU, a reliable execution of the the power-off control module
can be realized.

      Fig. 1 shows the logic of reset pulse generation and power
switch monitoring.  When the power switch is turned off, a reset
pulse is generated and input to the SMCU.

      After the reset of the SMCU, the SMCU checks the reason of the
reset, POR(Power On Reset) or power switch off, through the
monitoring pin.  In case of the power switch off, only the power-off
control module is executed (Fig. 2).

      According to this method, even though the SMCU is in any state,
the power...