Capacitance detection circuit

Abstract

The invention provides a capacitance detection circuit. The capacitance detection circuit comprises N induction units, a transfer capacitor, a charging module for charging the transfer capacitor and a controller, wherein the N is an integer larger than or equal to 1, one end of the transfer capacitor is respectively connected with the N induction units, the other end of the transfer capacitor is grounded, the transfer capacitor is used for transferring charge to capacitors in scanned induction units in the N induction units, the charging module comprises a first switch and a first resistor which are connected in series, the controller is respectively connected with the charging module and the transfer capacitor and used for controlling turn-off of a first switch when voltage of the transfer capacitor is larger than a preset threshold value, controlling turn-off of the first switch and meanwhile updating a count value when voltage of the transfer capacitor is smaller than the preset threshold value and detecting the touch condition of the N induction units according to the count value. The capacitance detection circuit can eliminate the capacitor influence, accordingly improve the detection accuracy and greatly improve the judgment accuracy.

Description

technical field [0001] The invention relates to the technical field of capacitance detection, in particular to a capacitance detection circuit. Background technique [0002] Currently, touch screens are used in electronic devices such as mobile phones, PDAs (Personal Digital Assistants), GPS (Global Positioning System), PMPs (MP3, MP4, etc.) and even tablet computers. The touch screen has the advantages of simple, convenient and humanized touch operation, so the touch screen is expected to become the best interface for human-computer interaction and has been widely used in portable devices. And along with the wide application of touch screen, people are also more and more in-depth to the research of touch screen technology. [0003] In the prior art, it is often judged whether the sensing unit is touched by detecting the self-capacitance of the sensing unit in the touch screen. Therefore, how to accurately detect the self-capacitance generated when the sensing unit in the t...

AI Technical Summary

Problems solved by technology

[0004] The disadvantage of the existing capacitance detection principle is that when detecting the capacitance generated by the touch of the sensing unit, due to the existence of mutual capacitance, it is often affected by the mutual capacitance, resulting in a certain error in detection, so the detection accuracy is not high enough. , and thus cannot accurately determine whether the sensing unit is touched

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