Force-sensing modules for light sensitive screens

• US 8,319,739 B2
• Filed: 03/13/2009
• Issued: 11/27/2012
• Est. Priority Date: 12/23/2008
• Status: Expired due to Fees

• Current Assignee: Integrated Digital Technologies, Inc. (InterDigital, Inc.)
• Original Assignee: Integrated Digital Technologies, Inc. (InterDigital, Inc.)
• Inventors: Hwang, Naejye, Chu, Chen-Chi
• Primary Examiner(s): HUBER, PAUL W
• Application Number:
  US12/403,415
• Publication Number:
  US 20100156852A1
• Time in Patent Office: 1,355 Days
• Field of Search: None
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/042 by opto-electronic means

Abstract

A light sensitive screen includes at least one sensing element each being configured to detect a force applied to a position of the light sensitive screen and generate an electrical signal when a force is detected, and a sensor module configured to receive and process the electrical signal from the at least one sensing element. The sensor module may amplify the electrical signal from one of the at least one sensing element and generate an amplified signal, compare the amplified signal with a threshold and generate a comparing result, and generate a digital signal based on the comparing result, the digital signal including information as to whether the position of the light sensitive screen is touched.

Claims

1. A light sensitive screen comprising:

at least one sensing element each being configured to detect a force applied to a position of the light sensitive screen and generate an electrical signal when a force is detected, the electrical signal including a positive half and a negative half; and

a sensor module configured to receive and process the electrical signal from the at least one sensing element, the sensor module comprising;

an amplifier configured to amplify the electrical signal from one of the at least one sensing element and generate an amplified signal;

a comparator configured to compare one of the positive half and the negative half with a threshold and generate a first voltage signal and a second voltage signal, the first voltage signal and the second voltage having the same amplitude with different signs; and

a digitizer configured to generate a digital signal based on the first voltage signal and the second voltage signal, the digital signal including information as to whether the position of the light sensitive screen is touched.

2. The light sensitive screen of claim 1, wherein each of the at least one sensing element includes one of a piezoelectric element or a piezoresistive element.

3. The light sensitive screen of claim 1, wherein the amplifier includes a pre-amplifier and a filter.

4. The light sensitive screen of claim 1, wherein the comparator compares a positive half of the amplified signal with a first threshold and compares a negative half of the amplified signal with a second threshold.

5. The light sensitive screen of claim 1, wherein the digitizer includes an SR latch further including a first input to receive one of the first voltage signal and the second voltage signal, and a second input to receive the other one of the first voltage signal and the second voltage signal.

6. The light sensitive screen of claim 5, wherein the digital signal includes an active period from a setting time point till a reset time point of the SR latch.