Browse Prior Art Database

Keyboard with Membrane Sheet Technology for a Notebook PC

IP.com Disclosure Number: IPCOM000123442D
Original Publication Date: 1998-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Horiuchi, M: AUTHOR [+3]

Abstract

Disclosed is a shielding method for a notebook type Personal Computer (PC) keyboard, implemented using multiple membrane sheet layers.

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This is the abbreviated version, containing approximately 100% of the total text.

Keyboard with Membrane Sheet Technology for a Notebook PC

   Disclosed is a shielding method for a notebook type
Personal Computer (PC) keyboard, implemented using multiple membrane
sheet layers.

   Figure 1 is a cross-sectional view through the front
side of the keyboard, exhibiting the location of the membrane
layers.  Figure 2 displays the structure of the various membrane
sheet layers.  Each sheet has electrical signal patterns(Silver
Paste Pattern) running across its surface.  These patterns combine to
make up the matrix of digital switches each associated with a key on
the keyboard.  The action of pressing a key is then sent across the
electrical patterns via a high-speed digital signal, and then
captured by a control unit.  The voltage level exhibited across the
electrical patterns is no more than 5V.

   Figure 3 displays an additional ground-shielding layer on
the surface of the upper membrane sheet.  This layer helps not only
to protect against ESD (Electrostatic Discharge) from outside of the
keyboard, but also to block any EMI (Electromagnetic Interference)
radiation noise that can leak through from the internal components of
the system.  In addition, this ground-shielding layer also prevents
cross-talk noise that could exist between the digital signal present
of the lower membrane layers and the low voltage (on the order of
micro voltage) cable located above the ground-shielding layer, which
is used for the pointing device(See Figure 4).