Sensor panel position coordinates signal detecting circuit

• US 6,489,575 B2
• Filed: 04/28/1999
• Issued: 12/03/2002
• Est. Priority Date: 08/14/1998
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Do-youn
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): ZAMANI, ALI A
• Application Number:
  US09/300,924
• Publication Number:
  US 20020044137A1
• Time in Patent Office: 1,315 Days
• Field of Search: 345/173, 345/176, 345/104, 345/174, 345/178, 178/18.01, 178/18.02, 178/18.03, 178/18.04, 178/18.05, 178/19
• US Class Current: 178/18.05
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A position coordinates signal detecting circuit of a sensor panel is provided. The position coordinates signal detecting circuit of the sensor panel according to the present invention includes first through fourth resistors each of which has one end connected to one of the left upper-most edge, the left lower-most edge, the right upper-most edge, and the right lower-most edge of the sensor panel. First through fourth driving signal generators are respectively connected to the other side of the first through fourth resistors for generating a driving signal so as to drive the sensor panel. Analog switches receive first through fourth pairs of voltages respectively generated at both ends of the first through fourth resistors. The first through fourth pairs of voltage are multiplexed in response to first through fourth selecting signals to provide a multiplexed signal, and a differential amplifier for amplifies the multiplexed signal. The position coordinates detecting circuit of the sensor panel according to the present invention makes it possible to amplify the voltage difference between both end of the variable resistors. Thus, the characteristics mismatching between different amplifiers is reduced, and the position coordinates are detected accurately.

Claims

1. An apparatus for detecting position coordinates of a contact point in a sensor panel coated with resistance component, comprising:

a plurality of resistors, each resistor having a first end connected to an edge of the sensor panel;

a plurality of driving signal generators, each driving signal generator being connected to a respective second en of one of the plurality of resistors for generating a driving signal so as to drive the senor panel connected to the first ends of the resistors;

an analog switching unit for (i) receiving a plurality of pairs of voltages corresponding respectively to the plurality of resistors, each voltage of each pair of voltages being generated at one of the first and second ends of the corresponding resistor, (ii) multiplexing the pairs of voltages in response to selecting signals, and (iii) providing a multiplexed output signal, the multiplexed output signal including a single selected one of the pairs of voltages, the analog switching unit comprising;

a plurality of pairs of switching circuits receiving respective ones of the pairs of voltages, each switching circuit of one of the pairs of switching circuits receiving one of pair of voltages received by the pair of switching circuits, and

a plurality of select circuits associated with respective pairs of switching circuits, each selection circuit being actuable by the selection signal to apply its respective pair of voltages to an output of the analog switching unit to generate the multiplexed output signal; and

a single differential amplifier for receiving the multiplexed output signal and for amplifying the multiplexed output signal, such that the single differential amplifier is used to amplify all of the pairs of voltages from the analog switch one at a time as each of the pairs of voltages is selected in response to the selecting signal.

2. The apparatus of claim 1, wherein the resistors are variable resistors.

3. The apparatus of claim 1 wherein the analog switching unit comprises a plurality of switches for receiving the pairs of voltages and selectively outputting one of the pairs of voltages in response to select signal.

4. The apparatus of claim 3, wherein each switch comprises:

a first switch for receiving the voltage level at one of the first and second ends of a corresponding resistor among the plurality of resistors as a first voltage level and selectively providing the first voltage level in response to the select signal; and

a second switch for receiving the voltage level at the other of the first and second ends of the corresponding resistor as a second voltage level and selectively providing the second voltage level in response to the select signal.

5. The apparatus of claim 4, wherein each of the first and second switches comprises:

an inverter for receiving and inverting the select signal and providing an inverted select signal; and

a transfer gate for selectively outputting a voltage level input in response to the select signal and the inverted select signal.

6. The apparatus of claim 1 comprising four resistors each of which is connected to one of four edges of the sensor panel.