Stylus, pressure detecting system and driving method thereof

Abstract

A stylus includes a pressure detector for detecting applied pressure, a first signal generator for generating a signal of a first frequency, a second signal generator for generating a signal of a second frequency, and a controller for adjusting at least one of the first and second signal generators to control an amplitude ratio of the signal of the first frequency to the signal of the second frequency according to the applied pressure detected by the pressure detector.

What is claimed is: 
     
         1 . A stylus comprising:
 a pressure detector for detecting applied pressure;   a first signal generator for generating a signal of a first frequency;   a second signal generator for generating a signal of a second frequency; and   a controller for adjusting at least one of the first and second signal generators to control an amplitude ratio of the signal of the first frequency to the signal of the second frequency according to the applied pressure detected by the pressure detector.   
     
     
         2 . The stylus according to  claim 1 , wherein the first frequency and the second frequency are different from each other. 
     
     
         3 . The stylus according to  claim 1 , wherein the first and second signal generators are respectively configured to emit the signals of the first and second frequencies through a single signal emitter. 
     
     
         4 . The stylus according to  claim 1 , wherein the first signal generator and the second signal generator respectively emit the signal of the first frequency and the signal of the second frequency through different signal emitters. 
     
     
         5 . The stylus according to  claim 1 , wherein the controller is configured to change an amplitude of only one of the signals of the first and second frequencies to control the amplitude ratio of the signals of the first and second frequencies. 
     
     
         6 . The stylus according to  claim 1 , wherein the controller is configured to change both an amplitude of the signal of the first frequency and an amplitude of the signal of the second frequency to control the amplitude ratio of the signals of the first and second frequencies. 
     
     
         7 . A pressure detecting system comprising:
 a stylus comprising:
 a pressure detector for detecting applied pressure; 
 a first signal generator for generating a signal of a first frequency; 
 a second signal generator for generating a signal of a second frequency; and 
 a controller for adjusting at least one of the first and second signal generators to control an amplitude ratio of the signal of the first frequency to the signal of the second frequency according to the applied pressure detected by the pressure detector; and 
   a pressure detecting apparatus for receiving the signals of the first and second frequencies from the stylus, and for detecting the applied pressure according to the amplitude ratio of the signal of the first frequency to the signal of the second frequency.   
     
     
         8 . The pressure detecting system according to  claim 7 , wherein the first frequency and the second frequency are different from each other. 
     
     
         9 . The pressure detecting system according to  claim 7 , wherein the first signal generator and the second signal generator respectively emit the signal of the first frequency and the signal of the second frequency through a single signal emitter. 
     
     
         10 . The pressure detecting system according to  claim 7 , wherein the first signal generator and the second signal generator respectively emit the signal of the first frequency and the signal of the second frequency through different signal emitters. 
     
     
         11 . The pressure detecting system according to  claim 7 , wherein the controller is configured to change an amplitude of only one of the signals of the first and second frequencies to control the amplitude ratio of the signals. 
     
     
         12 . The pressure detecting system according to  claim 7 , wherein the controller is configured to change both the amplitude of the signal of the first frequency and the amplitude of the signal of the second frequency to control the amplitude ratio of the signals. 
     
     
         13 . A driving method of a pressure detecting system, the method comprising:
 detecting applied pressure;   controlling an amplitude ratio of a signal of a first frequency to a signal of a second frequency according to the detected applied pressure;   emitting the signal of the first frequency and the signal of the second frequency;   receiving the signal of the first frequency and the signal of the second frequency;   calculating the amplitude ratio of the signal of the first frequency to the signal of the second frequency; and   calculating the pressure from the calculated amplitude ratio.   
     
     
         14 . The method of  claim 13 , wherein the first frequency and the second frequency are different from each other. 
     
     
         15 . The method of  claim 13 , wherein controlling the amplitude ratio comprises changing an amplitude of only one of the signals of the first and second frequencies to control the amplitude ratio of the signals. 
     
     
         16 . The method of  claim 13 , wherein controlling the amplitude ratio comprises changing both an amplitude of the signal of the first frequency and an amplitude of the signal of the second frequency to control the amplitude ratio of the signals.