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Alarm by on-board accelerometer against moving notebook PC

IP.com Disclosure Number: IPCOM000019124D
Original Publication Date: 2003-Aug-29
Included in the Prior Art Database: 2003-Aug-29
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Abstract

This invention enables the following functions by using an accelerometer and an embedded controller on a mother board, without additional hardware device. (1) To alert to a user that the user is trying to move or carry a notebook PC, even though the HDD in the PC is being accessed (2) To prevent unnecessary alarm beep sound, when the device driver for the HDD head unloading function is working (3) To alarm beep sound regardless of the system audio settings by controlling the volume and mute signals via the embedded controller

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Alarm by on-board accelerometer against moving notebook PC

- Background An alarm device using an accelerometer is already available. However, its purpose is not for protection of a HDD but for antitheft. A HDD protection system using an accelerometer is also available. This system protects a HDD from excessive shock or viblation by unloading of a disk head. However, this system is controlled by device driver. So, if the device driver is not installed or cannot work (like a period of entering suspend or hibernation mode), there is no way to protect the HDD.

- Description

This invention consists of four function blocks as the above figure, and the each blocks have following functions.

(A) Motion Detection : Monitor a output signal from the accelerometer to detect movement of Notebook PC
(B) HDD Access Monitor : Monitor a HDD access indication signal to detect HDD activity
(C) Host Interface : Interface to control enabling/disabling of this function
(D) Beep Control : Control of Volume and mute signals and output beep sound

(A) Motion Detection The accelerometer used this system has following characteristics.

- dual axis (X/Y axis)

- full scale renge of +/- 2G acceleration

- less than 2mG resolution

- analog level output with 500mV/G sensitivity

- 3.3V operation The embedded controller has mimimum two 10bit A/D converter input pins.

The analog output signals are connected to the A/D converter input pins on the embedded controller. The embedded controller monitors those signals and processes the data to detect movement of a system. The following shows a sample of data processing for movement detection.

1) Calculate moving average of sampled data

2) Store the minimum and maximum value...