Pressure sensitive stylus

Abstract

An apparatus includes a housing, a tip that moves with respect to the housing based on applied contact force and a pressure sensor that detects the force applied on the tip. The pressure sensor includes a first element integrated or fixed to the tip and a second element that is stationary with respect to the housing and positioned to face the first element. The first element is formed from a rigid material that is conductive. The second element is conductive and has elastic properties. In addition, one of the first element or the second element is coated with a non-conductive layer. The first element moves toward the second element based on force applied on the tip and deforms the second element based on the force. The sensor additionally includes a circuit to detect capacitance between the first element and the second element.

1 . (canceled) 
     
     
         2 . A stylus comprising a housing and a tip, the stylus further comprising:
 a pressure sensor configured to detect force applied to the tip, wherein the pressure sensor includes:   a first element;   a second element positioned within the housing, wherein the second element is at least partially conductive and comprises a deformable elastomer, wherein the second element is at least partially coated with a layer of non-conductive material on the deformable elastomer facing toward the first element; and   a circuit configured to detect capacitance between the first element and the second element to determine a stylus input based on the detected capacitance.   
     
     
         3 . The stylus of  claim 2 , wherein the non-conductive material is silicon. 
     
     
         4 . The stylus of  claim 2 , wherein the non-conductive material is a plasma. 
     
     
         5 . The stylus of  claim 2 , wherein the non-conductive material is an anodized material. 
     
     
         6 . The stylus of  claim 5 , further comprising an elastic element mechanically coupled to the housing and the tip, the elastic element being configured to provide a pre-load force on the tip. 
     
     
         7 . The stylus of  claim 2 , wherein the first element is dome shaped or cone shaped. 
     
     
         8 . The stylus of  claim 2 , wherein the second element has a flat shape. 
     
     
         9 . The stylus of  claim 2 , further comprising a thin oxidation layer applied to the first element, wherein the first element is a rigid element. 
     
     
         10 . The stylus of  claim 9 , wherein the thin oxidation layer spans a width of 10 nm to 10 μm 
     
     
         11 . The stylus of  claim 2 , further comprising an output sensor configured to transmit a pressure signal to a computing device, the pressure signal being captured based on deformation of the deformable elastomer. 
     
     
         12 . A stylus comprising a housing and a tip, the stylus further comprising:
 a pressure sensor configured to detect force applied to the tip, wherein the pressure sensor includes:   a first element;   a second element positioned within the housing, wherein the second element is at least partially conductive and comprises a deformable elastomer, wherein the second element is at least partially coated with a layer of non-conductive silicone on the deformable elastomer facing toward the first element; and   a circuit configured to detect capacitance between the first element and the second element to determine a stylus input based on the detected capacitance.   
     
     
         13 . The stylus of  claim 12 , further comprising an elastic element mechanically coupled to the housing and the tip, the elastic element being configured to provide a pre-load force on the tip. 
     
     
         14 . The stylus of  claim 12 , wherein the first element is dome shaped or cone shaped. 
     
     
         15 . The stylus of  claim 12 , wherein the first element is partially formed from metal. 
     
     
         16 . The stylus of  claim 12 , wherein the tip is an elongated element including a first end configured to extend out of the housing. 
     
     
         17 . The stylus of  claim 12 , further comprising an output sensor configured to transmit a pressure signal to a computing device, the pressure signal being captured based on deformation of the deformable elastomer. 
     
     
         18 . A system, comprising:
 a computing device comprising a touch screen; and   a stylus comprising:
 a housing; 
 a tip configured to move with respect to the housing based on contact force applied the writing tip; 
 a first element, 
 a second element positioned within the housing, wherein the second element is at least partially conductive and comprises a deformable elastomer, wherein the second element is at least partially coated with a layer of non-conductive material on the deformable elastomer facing toward the first element, and 
 a pressure sensor configured to detect force applied on the tip based on deformation of the deformable elastomer. 
   
     
     
         19 . The system of  claim 18 , wherein the non-conductive material is silicon. 
     
     
         20 . The system of  claim 18 , wherein the non-conductive material is an anodized material. 
     
     
         21 . The system of  claim 18 , further comprising an output sensor configured to transmit a pressure signal with the detected force to a computing device.