Multi-touch sensing circuit

• US 8,643,609 B2
• Filed: 11/13/2009
• Issued: 02/04/2014
• Est. Priority Date: 12/01/2008
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Original Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Inventors: Yu, Jae-suk, Choi, Yoon-kyung, Kim, Hyoung-tae, Lee, Joo-hyeon
• Primary Examiner(s): GIESY, ADAM
• Application Number:
  US12/618,264
• Publication Number:
  US 20100134438A1
• Time in Patent Office: 1,544 Days
• Field of Search: None
• US Class Current: 345/173
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A multi-touch sensing includes a voltage-current converter converting an input voltage into a current. A touch sensing block senses touch of an object. An amplifier includes a first input terminal connected to an output terminal of the voltage-current converter and to a first terminal of the touch sensing block. A second input terminal of the amplifier is grounded. An output terminal of the amplifier is connected to a second terminal of the touch sensing block.

Claims

1. A multi-touch sensing circuit comprising:

a voltage-current converter that converts an input voltage into a current;

a touch sensing block that is driven by the current and senses touch of an object by using a capacitor internally formed, wherein the capacitance of the capacitor varies according to the touch of an object; and

an amplifier,

wherein a first input terminal of the amplifier is connected to an output terminal of the voltage-current converter and to a first terminal of the touch sensing block, a second input terminal of the amplifier is grounded, and an output terminal of the amplifier is connected to a second terminal of the touch sensing block.

2. The multi-touch sensing circuit of claim 1, wherein magnitude and frequency of the input voltage vary.

3. The multi-touch sensing circuit of claim 2, further comprising a voltage source that generates the input voltage.

4. The multi-touch sensing circuit of claim 1, wherein the touch sensing block senses touch of a capacitive load.

5. The multi-touch sensing circuit of claim 1, further comprising a reset switch in which a first terminal of the reset switch is connected to the first terminal of the amplifier and a second terminal of the reset switch is connected to the output terminal of the amplifier.

6. The multi-touch sensing circuit of claim 1, wherein the touch sensing block is configured to sense a touch by a finger of a user.

7. The multi-touch sensing circuit of claim 1, wherein an output voltage of the amplifier varies according to the variation of the capacitance when an object touches the touch sensing block.

8. The multi-touch sensing circuit of claim 1, further comprising a reset switch coupleable in parallel with the touch sensing block.

9. A touch sensing apparatus, comprising:

a touch panel comprising;

a plurality of substantially parallel row circuit lines;

a plurality of substantially parallel column circuit lines insulated from the substantially parallel row circuit lines such that a capacitance is formed between a respective one of the substantially parallel row circuit lines and a respective one of the substantially parallel column circuit lines;

a switching circuit coupled to each of the substantially parallel row circuit lines and to each of the substantially parallel column circuit lines and configured to provide an output circuit path to output the capacitance in response to switching circuit control signals; and

an amplifier coupled to the touch panel in parallel,

wherein a first input terminal of the amplifier is connected to a first terminal of the touch panel, a second input terminal of the amplifier is grounded, and an output terminal of the amplifier is connected to a second terminal of the touch panel, and

wherein the touch panel is driven by a current received through the first input terminal.

10. The touch sensing apparatus of claim 9, wherein the capacitance is variable upon an external capacitive load being applied to an area proximate to the respective one of the substantially parallel row circuit lines and the respective one of the substantially parallel column circuit lines.

11. The touch sensing apparatus of claim 10, wherein the switching circuit comprises:

a respective row switch coupled between a common row output line and a respective row circuit line;

a respective column switch coupled between a common column output line and a respective column circuit line; and

a switch controller, that provides the switching control signals, coupled to each respective row switch and to each respective column switch,

wherein the common row output line and the common column output line provide the output circuit path when the switching control signals close the respective row switch and the respective column switch.

12. The touch sensing apparatus of claim 11, wherein the switch controller provides respective switching control signals to close a respective row switch and to close each of the column switches sequentially while the respective row switch remains closed.

13. The touch sensing apparatus of claim 11, wherein the common row output line is coupled to an input terminal of the amplifier and the common column output line is coupled to an output terminal of the amplifier.

14. The touch sensing apparatus of claim 13, further comprising a voltage-current converter whose output is coupled to the input terminal of the amplifier such that an input current is provided to the amplifier based upon a voltage being input to the voltage-current converter.

15. A multi-touch sensing circuit comprising:

a voltage-current converter that converts an input voltage into a current;

a touch sensing block that is driven by the current and senses touch of an object by using a variation of capacitance of a capacitor internally formed; and

an amplifier,

wherein a first input terminal of the amplifier is connected to an output terminal of the voltage-current converter and to a first terminal of the touch sensing block, a second input terminal of the amplifier is grounded, and an output terminal of the amplifier is connected to a second terminal of the touch sensing block,

wherein the voltage-current converter is an operational trans-conductance amplifier.

16. The multi-touch sensing circuit of claim 15, wherein the touch sensing block comprises:

a horizontal line control switch block comprising a plurality of horizontal line control switches in which a first terminal of each of the horizontal line control switches is commonly connected to the first input terminal of the amplifier and a second terminal of each of the horizontal line control switches is connected to a respective one of a plurality of horizontal lines disposed in a section where touch is sensed; and

a vertical line control switch block comprising a plurality of vertical line control switches in which a first terminal of each of the vertical line control switches is commonly connected to the output terminal of the amplifier and a second terminal of each of the vertical line control switches is connected to a respective one of a plurality of vertical lines disposed in a section where touch is sensed,

wherein insulation material is interposed between the pluralities of horizontal lines and vertical lines.

17. The multi-touch sensing circuit of claim 16, further comprising a control block that generates control signals used to control control switches of the horizontal line control switch block and to control switches of the vertical line control switch block.

18. The multi-touch sensing circuit of claim 16, wherein the pluralities of horizontal lines and vertical lines are disposed at a side or both sides of a touch screen of a display panel.