Browse Prior Art Database

Palm Sensor for Handheld Computing Devices

IP.com Disclosure Number: IPCOM000119187D
Original Publication Date: 1997-Dec-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 124K

Publishing Venue

IBM

Related People

Khanna, V: AUTHOR [+3]

Abstract

Portable computing devices are generally more susceptible to shock damage under operating conditions as compared to non-operating conditions. The present device uses a sensor to monitor the presence of the user's hand on a hand-held computing device. The sensor is used to detect the possible onset of shock due to accidental removal of the hand and to switch the device from operating to non-operating condition.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Palm Sensor for Handheld Computing Devices

      Portable computing devices are generally more susceptible to
shock damage under operating conditions as compared to non-operating
conditions.  The present device uses a sensor to monitor the presence
of the user's hand on a hand-held computing device.  The sensor is
used to detect the possible onset of shock due to accidental removal
of the hand and to switch the device from operating to non-operating
condition.

      Portable computing devices are generally more fragile when they
are in an operating mode, since operating shock levels for components
such as hard disks are generally significantly lower than
non-operating shock failure limits.  For example, operating shock
limits for most disk  drives are about 100g, while non-operating
shock limits can be more than  500g.  Hence, it is desirable to
detect the onset of a large shock during  operating conditions and to
switch the device to a non-operating mode before the shock actually
occurs.

      Typically, the technique used to decide the onset of a large
shock is to decide if the device is being accidentally dropped.  The
only method for detecting that the device is falling is to sense
zero-g through an accelerometer embedded in the device.  However,
even though  the idea of using a zero-g sensor for operating shock
protection has been  disclosed in the literature before, implementing
such a solution has many  practical difficulties.  In particular, a
zero-g sensor is sensitive to  the orientation of the device and care
must be taken to ensure that the  sensor is not triggered falsely if
the device is rotated.  In addition,  the normal operating
environment of a portable computing device consists  of shocks and
vibrations of tens of gs.  Mild shocks and accelerations  can be
imparted to the device as it sits on the lap or is held in the
user's hand.  Hence, a zero-g sensor must be able to decide the
presence or absence of one g in a particular direction in the
presence of noise  of tens of gs, which is extremely difficult.

      A general portable computing device, such as a laptop, can be
used during operation in a variety of modes such as on the user's
lap, on a desk, etc.  In contrast, a hand-held computing device, such
as a Personal Digital Assistant, a Personal Communicator or a
hand-held Point  of Sale Terminal, will generally be held in one hand
by the user during  its operation.  The device uses this fact to
detect accidental drops and  to switch the device from an operational
to non-operational state.

      The device works by employing a p...