Method for compensating electromagnetic inductive pressure level

• US 8,941,626 B1
• Filed: 10/02/2013
• Issued: 01/27/2015
• Est. Priority Date: 07/25/2013
• Status: Expired due to Fees

• Current Assignee: Waltop International Corp.
• Original Assignee: Waltop International Corp.
• Inventors: Yeh, Chia-Jui, Chang, Yu-Kuan
• Primary Examiner(s): OSORIO, RICARDO
• Application Number:
  US14/043,930
• Publication Number:
  US 20150029133A1
• Time in Patent Office: 482 Days
• Field of Search: 345/156, 345179-184, 178 1901- 1907
• US Class Current: 345/179
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A method for compensating electromagnetic inductive pressure level of an electromagnetic pen is disclosed. First of all, an electromagnetic pen is provided on a touch panel, wherein the touch panel has a sensor layer and at least one sensor coil on a transparent substrate, the sensor coil is located on the peripheral region of the transparent substrate and around the sensor layer. Then a signal amplitude of the electromagnetic pen is calculated and a pressure level value is calculated via a frequency of the electromagnetic pen. Next distances between the sensor coil and the electromagnetic pen are calculated to obtain the location of the electromagnetic pen. Then a pressure level compensation value is obtained from a pressure level compensation value table. Finally, a compensated pressure level value is obtained by adding the pressure level value and the pressure level compensation value.

Claims

1. A method for establishing a pressure level compensation value table for an electromagnetic pen, comprising:

providing an electromagnetic pen with a standard or predetermined frequency and a standard or predetermined signal amplitude on a touch panel, wherein the touch panel has a sensor layer and at least one sensor coil on a transparent substrate, the sensor coil is located on the peripheral region of the transparent substrate and around the sensor layer;

measuring signal amplitudes of the electromagnetic pen on predetermined locations on the touch panel;

calculating distances between the electromagnetic pen and the sensor coil by calculating the differences between the measured signal amplitudes and the predetermined signal amplitude;

measuring frequencies of the electromagnetic pen on the predetermined locations on the touch panel; and

establishing a pressure level compensation table via obtaining frequency error values of the predetermined locations by calculating the differences between the measured frequencies of the electromagnetic pen on the predetermined locations and the standard frequency.

2. A method for compensating electromagnetic inductive pressure level of an electromagnetic pen, comprising:

providing an electromagnetic pen on a touch panel, wherein the touch panel has a sensor layer and at least one sensor coil on a transparent substrate, the sensor coil is located on the peripheral region of the transparent substrate and around the sensor layer;

calculating a signal amplitude of the electromagnetic pen and calculating a pressure level value according to a frequency of the electromagnetic pen;

calculating a distance between the electromagnetic pen and the sensor coil according to the signal amplitude to locate the electromagnetic pen;

obtaining a pressure level compensation value from the pressure level compensation value table of claim 1; and

obtaining a compensated pressure level value by adding the pressure level value and the pressure level compensation value.

3. The method of claim 1, wherein the sensor layer comprises a plurality of capacitive detection electrodes.

4. The method of claim 3, wherein the electromagnetic pen comprises a conductive pin.