Waltop International Corp

Waltop International Corp is a worldwide company that produces graphics tablets and related products, headquartered in Hsinchu City, Taiwan. At 2004 November, It spun off from Aiptek International Inc as a independent subsidiary<ref name="AboutWaltop01" />. In 2006, the UMC capital corporation, a wholly-owned venture capital company of UMC group (United Microelectronics Corporation), acquired more than 40% Waltop's stocks and has become new major stockholder.
Electromagnetic pen technology
The company's main product is the graphics tablet (electromagnetic digitizers) that typically consist of a tablet pad and an electromagnetic pen-type stylus.

These electromagnetic pens are classified into two types: battery-powered and battery-free.
*Battery-powered pens<ref name="PenStructure01" /> use a battery as an internal power source, to actively emit electromagnetic wave signals<ref name="BatteryPen1" />. At any distance from the tablet, the electromagnetic pen can continously emit the correct signal, at a sufficient signal strength, to the table device. This approach has the drawback of requiring a heavier stylus.
*Battery-free pens have no internal power souce, but instead implement a resonant circuit for receiving a signal from the tablet's antenna.<ref name="BatteryfreeDigitizer1" /> The received energy is stored in the oscillator circuit. After the tablet stops sending energy, the pen emits back to the tablet the energy stored in resonant circuit. This approach has the benefits of a lighter pen, however it also has the drawback <ref name="BatteryfreePen1" /> of being unable to receive or transmit energy from greater than a certain distance from the tablet. Its weaker signal might also be interfered with by electromagnetic interference in the environment.
Electromagnetic pen technology in tablet PCs and e-Paper readers
Electromagnetic pens in tablet PC and E-Book devices have several advantages over resistive and capacitive type touch panels:
* Since matrix antennas only receive the EM pen's signal, there is no interference or influence when the user touches the tablet's surface.
* The pen's EM signal can be received normally about 30 mm distance<ref name="TabletProximity01" />, so the cursor can be controlled even with the pen hovering over the screen. That is why, it can be intergrated into the behind of a LCD panel and make the normal LCD becomes a Tablet LCD Panel<ref name="TabletProximity02" />.
* With integrated electromagnetic pens, there is no need to add a glass cover to the surface, and transparency is better than resistive touch panels.
The method for integrating the electromagnetic pen technology
Monitor manufacturers can integrate<ref name="TabletLCDStructure01" /> the EM pen-tablet into the behind of a LCD panel by following below steps:
* Choosing a LCD panel with the LED-backlight.
* To modify the back metal frame of LCD for:
** Fixing the control board of EM-tablet.
** Opening the slot<ref name="MetalFrame01" /> for FPC-cable
** To reserve the enough space<ref name="TabletProximity02" /> (about 0.6mm thinkness) for tablet's antenna board.
* To fine tune the firmware of pen-tablet for improving the jitter and proximity at edge area and corner area.

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