US-12625580-B2 - Touch detection device capable of suppressing EMI effect

US12625580B2US 12625580 B2US12625580 B2US 12625580B2US-12625580-B2

Abstract

A touch detection device includes a panel including a plurality of electrodes regularly arranged in rows and columns, a switch connected to electrodes arranged in a specific column through connection lines, and a sensor driving unit operably coupled to the switch and configured to perform a control operation so that a driving signal of a voltage waveform of a specific cycle is applied to the electrodes. Lengths of the connection lines are differently set according to positions of electrodes arranged in a specific row. The sensor driving unit applies a second driving signal of a reverse voltage waveform to an electrode of one of two rows adjacent to the specific row when an amount of electromagnetic interference (EMI) radiation of a specific connection line to which the driving signal is applied is less than or equal to a threshold.

Inventors

Dong-Won Yun
Hyung-Ki JIN

Assignees

G2TOUCH CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20250113
Priority Date: 20240403

Claims (10)

1 . A touch detection device comprising: a panel including a plurality of electrodes regularly arranged in rows and columns; a switch connected to electrodes arranged in one of the columns through connection lines including a first connection line and a second connection line; and a sensor driving unit operably coupled to the switch and configured to perform a control operation such that a driving signal of a voltage waveform of a specific cycle is applied to the electrodes arranged in the one of the columns, wherein: lengths of the connection lines are differently set according to positions of electrodes arranged in each of the rows, and the sensor driving unit is configured to: apply a second driving signal of a reverse voltage waveform to an electrode of one of two rows adjacent to one of the rows when an amount of electromagnetic interference (EMI) radiation of the first connection line to which the driving signal is applied is less than or equal to a threshold, and apply the second driving signal and a third driving signal of the reverse voltage waveform to electrodes of the two rows adjacent to the one of the rows, respectively, when the amount of EMI radiation of the first connection line exceeds the threshold.
2 . The touch detection device according to claim 1 , wherein the sensor driving unit is configured to: apply the second driving signal of the reverse voltage waveform to the electrode of the one of the two rows adjacent to the one of the rows when a length of the first connection line is greater than or equal to a critical length, and apply the second driving signal and the third driving signal of the reverse voltage waveform to the electrodes of the two rows adjacent to the one of the rows, respectively, when the length of the first connection line is less than the critical length.
3 . The touch detection device according to claim 2 , wherein: when the length of the first connection line is greater than or equal to the critical length, the driving signal of the voltage waveform is a square wave signal having a first slew rate at a rising edge, and when the length of the first connection line is less than the critical length, the driving signal of the voltage waveform is a square wave signal having a second slew rate greater than the first slew rate at a rising edge.
4 . The touch detection device according to claim 3 , wherein the sensor driving unit is configured to: detect a rising edge and a falling edge of the driving signal of the voltage waveform for each row, and perform a control operation such that time points of a second falling edge and a second rising edge of the second driving signal match and correspond to time points of the rising edge and the falling edge of the driving signal of the voltage waveform for each row when the length of the first connection line is greater than or equal to the critical length.
5 . The touch detection device according to claim 3 , wherein the sensor driving unit is configured to: detect a rising edge and a falling edge of the driving signal of the voltage waveform for each row, perform a control operation such that time points of a second falling edge and a second rising edge of the second driving signal match and correspond to time points of the rising edge and the falling edge of the driving signal of the voltage waveform for each row when the length of the first connection line is less than the critical length, and perform a control operation such that time points of a third falling edge and a third rising edge of the third driving signal match and correspond to time points of the rising edge and the falling edge of the driving signal of the voltage waveform for each row when the length of the first connection line is less than the critical length.
6 . The touch detection device according to claim 3 , wherein the columns include a first column, a second column, a third column, and a fourth column, and the switch includes: a first switch connected to electrodes of the first column; a second switch connected to electrodes of the second column adjacent to the first column; a third switch connected to electrodes of the third column adjacent to the second column; and a fourth switch connected to electrodes of the fourth column adjacent to the third column.
7 . The touch detection device according to claim 6 , wherein: the sensor driving unit is configured to: detect a row and a column corresponding to a position where touch input is applied to the panel, and apply driving signals of different voltage waveforms to electrodes in adjacent rows of the detected row through switches corresponding to the detected column among the first to fourth switches, and at least one of the driving signals of the different voltage waveforms is the second driving signal of the reverse voltage waveform.
8 . The touch detection device according to claim 7 , wherein, when the length of the first connection line is greater than or equal to the critical length, the sensor driving unit applies the second driving signal of the reverse voltage waveform to the second connection line adjacent to the one of the rows and shorter than the first connection line.
9 . The touch detection device according to claim 8 , wherein the connection lines further includes a third connection line, and wherein the sensor driving unit is configured to: apply the second driving signal of the reverse voltage waveform to the second connection line adjacent to the one of the rows and shorter than the first connection line when the length of the first connection line is less than the critical length, determine whether the amount of EMI radiation of the first connection line is greater than or equal to the threshold when the driving signal and the second driving signal are applied, and apply the third driving signal of the reverse voltage waveform to the third connection line adjacent to the one of the rows and longer than the first connection line when the amount of EMI radiation of the first connection line is greater than or equal to the threshold.
10 . The touch detection device according to claim 1 , wherein the sensor driving unit is configured to: detect a rising edge and a falling edge of the driving signal of the voltage waveform for each row, detect a first area between the rising edge and the falling edge, and cancel out an EMI component of the voltage waveform by changing a second area of the second driving signal of the reverse voltage waveform to correspond to the first area.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a method of driving a touch panel, and more particularly to a touch panel detection device capable of suppressing an EMI effect. Description of the Related Art Electromagnetic interference (EMI) is undesired noise or interference in an electrical path or circuit caused by a source, and is also referred to as radio frequency interference. EMI may cause electronic devices to improperly work, malfunction, or stop working completely. EMI may occur due to a natural or man-made source, and an EMI effect may be reduced using a high-quality electronic device, electrical shielding, and modern error correction. General examples of EMI include electrical noise that is heard when a mobile phone is placed near powered audio equipment or speakers. Electric current, which is movement of an electric charge, creates a magnetic field, and a moving magnetic field creates an electric current. An electrical conductor may act as an antenna for radio waves. High-power electrical and radio sources may have undesired effects on devices located far away. As electronic devices become smaller, faster, more compact, and more sensitive, the electronic devices become more susceptible to effects of radio waves, which generates EMI. This EMI may result from several sources. For example, high-power radio and electrical sources may cause undesired EMI. Improperly designed consumer electronic devices may cause EMI in other devices. Meanwhile, a touch panel includes a plurality of electrodes. An object such as a finger or a stylus provides input by changing capacitance between electrodes included in the touch panel. In order for the touch panel to detect the input provided by the object, a driving circuit needs to apply a driving signal. However, there is a problem in that EMI formed by the driving signal affects the plurality of electrodes and/or a plurality of driving circuits in the panel, so that detection performance deteriorates. In addition, in touch driving in the panel, a plurality of touch cells determines a quantity of electric charges of a capacitor through a voltage alternating current operation to recognize touch input. In this process, an electric field and a magnetic field are formed due to the voltage alternating current operation, which generates EMI. In particular, as the touch area increases, the number of touch cells operating at alternating current increases, and thus the EMI effect accelerates. In particular, application of a large touch sensor panel (TSP) is difficult, and the worst result is obtained in terms of EMI risk. SUMMARY OF THE INVENTION A task to be solved by the present invention is to solve such difficulties. A task to be solved by the present invention is to provide a method of driving a touch panel capable of reducing an EMI effect in the touch panel. A task to be solved by the present invention is to alleviate a problem that an amount of EMI radiation is different in magnitude for each sensing column since resistance and capacitance components of touch cells in a panel deviate more as the panel becomes larger. A task to be solved by the present invention is to provide a method of driving a touch panel capable of reducing an EMI deviation effect in the touch panel. However, the tasks to be solved by the present invention are not limited to the technical tasks mentioned above, and other technical tasks not mentioned herein may be clearly understood by a person having ordinary knowledge in the field from the description of the present invention. In accordance with the present invention, the above and other objects can be accomplished by the provision of a touch detection device including a plurality of electrodes regularly arranged in rows and columns, a switch connected to electrodes arranged in a specific column through connection lines, and a sensor driving unit operably coupled to the switch and configured to perform a control operation so that a driving signal of a voltage waveform of a specific cycle is applied to the electrodes. Lengths of the connection lines are differently set according to positions of electrodes arranged in a specific row. The sensor driving unit applies a second driving signal of a reverse voltage waveform to an electrode of one of two rows adjacent to the specific row when an amount of electromagnetic interference (EMI) radiation of a specific connection line to which the driving signal is applied is less than or equal to a threshold. According to an embodiment, the sensor driving unit applies the second driving signal and a third driving signal of the reverse voltage waveform to electrodes of the two rows adjacent to the specific row, respectively, when the amount of EMI radiation of the specific connection line exceeds the threshold. According to an embodiment, the sensor driving unit may apply the second driving signal of the reverse voltage waveform to the electrode of the one of two rows ad