Detection device and detection method of signal of projected capacitive touch screen

Abstract

The invention discloses a detection method of a signal of a projected capacitive touch screen for measuring a touch signal on a capacitive touch screen. The capacitive touch screen comprises a plurality of drive wires transversely arranged and a plurality of induction wires longitudinally arranged. The detection method comprises the steps of: driving one drive wire, comparing voltage values of two adjacent induction wires, carrying out self-capacitance compensation on the induction wire with a smaller voltage value, repeating the operation until the voltage values are equal; measuring the compensated self-capacitance value to obtain an amplified value of a capacitance difference value between the two adjacent induction wires; and sequentially driving a plurality of drive wires and measuring the amplified value of the capacitance difference value between the two adjacent induction wires, and obtaining the touch signal according to the measured data. In conclusion, the amplified value of capacitance change can be directly detected without amplifying the signal according to the detection method; the detection sensitivity is high, and the signal to noise ratio is also improved. The invention also discloses a corresponding detection device of the signal of the projected capacitive touch screen and another detection method of the signal of the projected capacitive touch screen.

Description

technical field [0001] The invention relates to a touch screen signal detection device and a detection method thereof, in particular to a projected capacitive touch screen signal detection device and a detection method thereof. Background technique [0002] There are various projected capacitive screens on the market, all of which adopt an open electric field structure. The capacitive screen is made by utilizing the principle that the open electric field is susceptible to external interference. Taking the prismatic panel as an example to analyze its working principle, the panel can be double-layered or single-layered (single-layered ones need to be insulated at the horizontal and vertical intersections). For example in figure 1 , the mutual capacitance value C between the second horizontal line and the second vertical line M =C 1 +C 2 +C 3 +C 4 , people are grounded conductors, Figure 2a is the electric field between the sensing line column and the driving line ROW e...

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Problems solved by technology

[0004] However, although the above method can eliminate ghost points and can be applied to multi-finger touch, there are still many problems. On the one hand, the number of charge amplifiers used in this method is too large, which increases the area and power consumption of the chip; on the other hand , this method has poor ability to suppress power supply noise and panel display noise, and the signal-to-noise ratio is low; on the other hand, the detection sensitivity of this method is low, because the detection result of this scheme represents the absolute value of mutual capacitance, while in fact When touching, the change of mutual capacitance is very small, and the corresponding signal change is also small

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