Circuit, touch chip, and electronic device for capacitance detection

#Embodiments of the present disclosure relate to the field of touch control technology, and in particular to, a circuit, touch chip, and electronic device for capacitance detection.

#The principle of self-capacitance detection is that a capacitor will be formed between a detection electrode and system ground, which is known as the self-capacitance detection. When no external electric field is caused by, e.g., a finger, the capacitor formed between the detection electrode and the system ground has base capacitance or initial capacitance. When the finger approaches or touches the detection electrode, the capacitance between the detection electrode and the system ground will be enhanced, and a user-related touch control operation may be determined by detecting a variation of the capacitance.

#In the field of capacitance touch control, the flexible screen is an important development direction. When implementing capacitance touch detection using the above self-capacitance principle, the flexible screen is often thinner than a conventional capacitance touch control, such that the detection electrode is closer to the system ground. Thus, the base capacitance of the capacitor is significantly higher than the base capacitance of the capacitor of the conventional capacitance touch screen. Further, since a metal-mesh is used as the detection electrode, the sensing area is relatively small, such that when the finger touches the capacitor, the capacitance variation is very small. A small capacitance variation means to require a high circuit gain, such that the detection circuit can detect an electrical signal generated by the capacitance variation during touching, but since the base capacitance is much higher than the capacitance variation, a high circuit gain, if employed, further tends to cause detection circuit saturation.

#Some specific embodiments of embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings, by an exemplary approach, instead of a non-limiting approach. Identical reference numerals in the accompanying drawings represent identical or similar components or parts. As will be appreciated by those skilled in the art, these accompanying drawings may not be drawn to scale. In the accompanying drawings:

#FIG. 1 is a schematic structural diagram of a system for capacitance touch control according to Embodiment I of the present disclosure;

#FIG. 2 is a schematic structural diagram of a circuit for capacitance detection according to Embodiment II of the present disclosure;

#Any technical solution of embodiments of the present disclosure may not necessarily be implemented to achieve all of the above advantages.

#In the technical solutions provided by embodiments of the present disclosure, a circuit for capacitance detection includes: a control module, a charge transfer module, a processing module, a driving module, and an offsetting module, the control module being configured to charge a detection capacitor by controlling the driving module, the offsetting module being configured to charge an offset capacitor, and control the offset capacitor to perform charge offsetting on the detection capacitor; the charge transfer module being configured to convert charge of the detection capacitor after the charge offsetting to generate an output voltage; and the processing module being configured to determine, based on the output voltage, a capacitance variation of the detection capacitor before and after the detection capacitor is affected by an external electric field. When the circuit is applied to self-capacitance detection, base capacitance of a detected detection capacitor may be eliminated or reduced by charge offsetting, thereby improving the capacitance variation rate and enhancing the sensitivity of the self-capacitance detection in a circumstance where the capacitance variation remains unchanged, and finally improving the accuracy of the self-capacitance detection.

#Specific implementations of the embodiments of the present disclosure will be further illustrated below in conjunction with the accompanying drawings of the embodiments of the present disclosure.