Microsoft wins patent for a surface pen with improved sensitivity
An improved capacitive pressure sensor is incorporated into the surface pen. Microsoft states in the patent that the improved surface pen sensor may be implemented at low cost.
Microsoft notes in the patent that, “Styluses are known in the art for use with a computing device.
Position detection of a stylus provides input to a digitizer sensor associated with the computing device and may be interpreted as user command. Position detection may be performed while a tip of the stylus is either touching and/or hovering over a detection surface of the digitizer sensor.
The digitizer sensor is often integrated within an electronic display screen and the computing device correlates position of the stylus with information portrayed on the screen.
Some styluses are pressure sensitive in that they sense and optionally report a level of pressure applied on the stylus tip while a user is using the stylus. An application executed on the computing device may then use this information.
For example, a graphic application may adjust line thickness or shade of a drawn line based on detected pressure levels.”
Microsoft’s Fig. 1 shown below is a simplified block diagram of an example pressure sensitive stylus
When a contact force #250 (not shown in Fig. 1) applied on end #151 overcomes the preload of elastic element #160, writing tip #150 together with tip holder #155 and rigid element #220 moves toward elastomer #210.
As rigid element #220 approaches elastomer #210, air gap #157 decreases and capacitive coupling increases. The resilient force applied by elastic element #160 may restore air gap #157 once force #250 is removed.
As force #250 increases, rigid element #220 is pushed against and deforms elastomer #210. Layer #225 maintains electrical isolation between rigid element #220 and elastomer #210 during contact.
Due to the dome shape of rigid element #220, surface contact area between rigid element #220 and elastomer #210 increases as rigid element further presses into and deforms elastomer #210. The increase in contact area increases capacitive coupling. Elastomer #210 may typically regain its neutral shape as force #250 is released and rigid element #220 is displaced from elastomer #210.
This patent, which has 20 claims was initially filed in January 2017. Vadim Mishalov and Ahia Peretz are named as inventors.
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