Touch controllers, methods thereof, and devices having the touch controllers

• US 9,195,353 B2
• Filed: 09/06/2012
• Issued: 11/24/2015
• Est. Priority Date: 09/09/2011
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Byun, San-Ho, Kim, Ki-Duk, Choi, Yoon Kyung
• Primary Examiner(s): LEE, NICHOLAS J
• Application Number:
  US13/605,247
• Publication Number:
  US 20130063395A1
• Time in Patent Office: 1,174 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard

Abstract

An operating method of a touch controller includes receiving a plurality of currents through a plurality of channels, respectively, sensing a first current among the plurality of currents and extracting the sensed first current as a first control current and converting a charge corresponding to a difference between the first control current and a second current among the plurality of currents into an output voltage.

Claims

1. A touch controller comprising:

a plurality of pins each connected to one of a plurality of channels;

a selector for selecting two of the plurality of channels in response to a selection signal; and

a differential sensing block configured to convert a charge corresponding to a difference between a first current and a second current flowing in each of the two channels into an output voltage.

2. The touch controller of claim 1, wherein the differential sensing block comprises:

a current conveyer configured to sense the first current and extract the sensed first current as a control current; and

a charge amplifier configured to convert a current difference between the second current and the control current into the output voltage.

3. The touch controller of claim 2, wherein the current conveyer comprises:

a unity gain buffer amplifier including a first input terminal configured to receive the first current, a second input terminal configured to receive an alternating voltage, and a first output terminal connected to the first input terminal; and

a current copy circuit including a second output terminal, the current copy circuit for extracting the control current according to a plurality of control voltages output from the unity gain buffer amplifier.

4. The touch controller of claim 3, wherein the current copy circuit comprises:

a sourcing circuit and a sinking circuit connected in series between a power node and a ground node of the unity gain buffer amplifier,

wherein each of the sourcing circuit and the sinking circuit is configured to operate based on the plurality of control voltages.

5. The touch controller of claim 4, wherein the control current is a difference between a current flowing in the sinking circuit and a current flowing in the sourcing circuit.

6. The touch controller of claim 1, wherein, if a plurality of sensors connected to each of the plurality of channels are not touched, the charge amplifier is configured to output a reference voltage as the output voltage.

7. The touch controller of claim 1, further comprising:

a mismatch compensation block connected to a display common electrode, the mismatch compensation block configured to compensate for a mismatch between a plurality of parasitic elements between the display common electrode and a sensor electrode in response to the output voltage.

8. The touch controller of claim 7, wherein the mismatch compensation block comprises:

a capacitor array including a plurality of capacitors; and

a selection bit generator configured to compare the output voltage with a comparison voltage to select at least one of the plurality of capacitors and generate a plurality of selection bits according to a comparison result.

9. The touch controller of claim 8, wherein the selection bit generator comprises:

a comparator configured to compare the comparison voltage with the output voltage and output a comparison signal; and

a successive approximation register (SAR) control logic configured to generate the plurality of selection bits in response to the comparison signal.

10. The touch controller of claim 9, wherein the SAR control logic is configured to generate a compensation clock signal and supply the compensation clock signal to a source driver.

11. A touch controller comprising:

a plurality of pins each connected to a plurality of channels;

a first current conveyer configured to sense a first current flowing in one of the plurality of channels and extract the sensed first current as a first control current;

a second current conveyer configured to sense a second current flowing in another channel of the plurality of channels and extract the sensed second current as a second control current; and

a charge amplifier configured to convert a current difference between the first control current and the second control current into an output voltage.

12. The touch controller of claim 11, further comprising:

a plurality of driving pins connected to the plurality of driving channels, and

an integrated circuit configured to supply a sign pulse signal to each of the plurality of driving channels.

13. The touch controller of claim 11, wherein the first current conveyer comprises:

a unity gain buffer amplifier including an inverting input terminal configured to receive the first current, a non-inverting input terminal configured to receive a reference voltage, and an output terminal connected to the inverting terminal; and

a current copy circuit configured to extract the first control current according to a plurality of control voltages output from the unity gain buffer amplifier.

14. The touch controller of claim 13, wherein the current copy circuit comprises:

a sourcing circuit and a sinking circuit connected in series between a power node and a ground node of the unity gain buffer amplifier,

wherein each of the sourcing circuit and the sinking circuit is configured to operate based on the plurality of control voltages.

15. The touch controller of claim 11, wherein the second current conveyer comprises:

a unity gain buffer amplifier including an inverting input terminal configured to receive the second current, a non-inverting input terminal configured to receive a reference voltage, and an output terminal connected to the inverting terminal; and

a current copy circuit configured to extract the second control current according to a plurality of control voltages output from the unity gain buffer amplifier.

16. The touch controller of claim 15, wherein the current copy circuit comprises:

a plurality of current mirrors each connected between a power node and a ground node of the unity gain buffer amplifier,

wherein each of the plurality of current mirrors is configured to operate based on the plurality of control voltages.

17. A touch display system comprising:

a touch display panel; and

a touch controller connected to the touch display panel by a plurality of channels,

wherein the touch controller includes,

a current conveyer configured to sense a first current among a plurality of currents flowing through each of the plurality of channels and extract the sensed first current as a control current; and

a charge amplifier configured to convert a charge corresponding to a difference between the control current and a second current among the plurality of currents into an output voltage.

18. The touch display system of claim 17, wherein the touch display system is a portable device.

19. A touch display system comprising:

a display panel configured to produce a plurality of currents through a plurality of channels, respectively;

an integrated circuit coupled to the plurality of channels, the integrated circuit including,

a differential sensor configured to receive a first current associated with a first channel and a second current associated with a second channel, generate a charge corresponding to a difference between the first and second currents, and convert the charge into an output voltage.

20. The touch display system of claim 19, wherein the integrated circuit further includes,

a mismatch compensator configured to compensate for parasitic capacitances in the display panel based on the output voltage.

21. The touch display system of claim 20, wherein the mismatch compensator includes,

a bit selection generator configured to receive the output voltage, compare the output voltage to a comparison voltage and generate a plurality of selection bits based on the comparison, and

a capacitor array configured to select at least one of a plurality of capacitors based on the plurality of selection bits to compensate for the parasitic capacitances.

22. The touch display system of claim 20, wherein the mismatch compensator is configured to selectively change a capacitance between a sensor electrode and a display common electrode to compensate for parasitic capacitances in the display panel.