Capacitive touch screen capable of improving interference resistance

Abstract

The utility model relates to a capacitive touch screen capable of improving interference resistance, which comprises a capacitive touch screen sensor, a touch chip and a system power supply part, the capacitive touch screen sensor is connected with the touch chip, and the touch chip is connected with the system power supply part; the touch chip comprises a receiving part and a transmitting part, and the receiving part of the touch chip comprises a signal receiving part, a touch driving circuit part and a band-pass filter; the system power supply part comprises a power supply part and a power supply interference signal suppression circuit; the capacitive touch screen is simple in structure, and the anti-interference performance of the capacitive touch screen can be effectively improved.

Description

Technical Field

[0001] The utility model relates to a capacitive touch screen, in particular to a capacitive touch screen with improved anti-interference. Background Art

[0002] Although the world's first real touch screen is a capacitive touch screen, unfortunately, capacitive touch screens were not put into mass production and use at that time, but resistive touch screens came later. Resistive touch screens are low-cost, long-life, and cost-effective, making them very suitable for large-scale commercial production. For a long time, resistive touch screens were the mainstream, but as the demand for multi-touch became more and more urgent, capacitive touch screens began to be widely used. Compared with resistive touch screens, capacitive touch screens support multi-touch, have high sensitivity, and display effects that are clear, bright, and colorful. However, capacitive touch screens have a fatal flaw, that is, they are easily affected by environmental factors including but not limited to temperature, humidity, magnetic fields, electric fields, etc., resulting in drift and misidentification, that is, poor stability and poor anti-interference. Summary of the invention

[0003] The technical problem to be solved by the utility model is to provide a capacitive touch screen with improved anti-interference performance, which has good anti-interference performance, high stability and can be applied to various harsh environments.

[0004] The utility model solves the above-mentioned technical problem with the following technical solution: a capacitive touch screen with improved anti-interference, comprising a capacitive touch screen sensor, a touch chip, and a system power supply part, wherein the capacitive touch screen sensor is connected to the touch chip, and the touch chip is connected to the system power supply part; the touch chip comprises a receiving part and a transmitting part, and the touch chip receiving part comprises a signal receiving part, a touch driving circuit part, and a bandpass filter; the system power supply part comprises a power supply part and a power supply interference signal suppression circuit.

[0005] The capacitive touch screen sensor Sensor is connected to the receiving part of the touch chip, that is, the signal receiving part of the touch chip receives the signal returned by the capacitive touch screen sensor Sensor; the capacitive touch screen sensor Sensor is connected to the touch driving circuit part, that is, the touch driving circuit drives the capacitive touch screen sensor Sensor part, so that the Sensor sensing part can effectively perform touch recognition; the system power supply part supplies power to the touch chip, so that it can perform signal triggering, signal recognition, and signal transmission on the basis of electricity.

[0006] On the basis of the above technical solution, the present invention can also be improved as follows.

[0007] Furthermore, the architecture of the capacitive touch screen sensor not only includes the necessary ITO wiring, but also includes a ground plane area unique to this solution; further, the ground plane area is the equipotential area of ​​the capacitive touch screen sensor, providing a ground plane and a current return path for the ITO; further, the ground plane area also has EMC performance. Since it has a complete ground plane, that is, a reference plane, a filtering channel is performed for external interference so that its interference is no longer superimposed on the ITO; further, the design area of ​​the ground plane area needs to be larger than the ITO area. This design is intended to achieve equipotential encirclement at the edge of the touch sensor, so that not only the entire recognition surface of the ITO can be placed on an equipotential surface, but also EMC processing can be achieved at the edge.

[0008] The beneficial effects of taking the above steps are: the capacitive touch screen sensor increases the equipotential surface to improve anti-interference and EMC performance; and plays a role of physical filtering in the capacitive touch recognition solution.

[0009] Furthermore, the main function of the touch chip signal receiving part is to receive and amplify the electrical signal generated by the weak capacitance change in the touch area of ​​the capacitive touch screen; further, the touch chip signal receiving part amplifies the electrical signal while performing pulse peak limiting suppression on the amplified signal; further, the touch chip signal receiving part suppresses the pulse peak of the amplified electrical signal and then sends it to a bandpass filter; the operating frequency generated by the non-touch chip transmitting end is filtered out by the bandpass filter, and only the operating frequency range of the touch chip is retained.

[0010] Furthermore, the touch chip signal receiving part recognizes human touch operation behavior based on the signal after bandpass filter processing; further, the touch chip signal receiving part adopts LFM technology, which requires comparison and identification of multi-band digital signals, and adopts digital filtering technology to perform multiple multi-frequency comparison processing on the signal, identify and discard the interference data, and confirm the valid signal again.

[0011] Furthermore, the LFM technology allows the frequency of the carrier signal to change linearly over time; in a linear frequency modulation pulse, the rate of change of the frequency (i.e., the frequency slope) is constant, which means that the instantaneous frequency of the signal increases or decreases linearly over time. Due to the extended spectrum characteristics of the LFM signal, it has a stronger ability to resist narrowband interference to a certain extent compared to a single frequency signal.

[0012] Furthermore, the human touch behavior recognition is to perform intervention recognition on the touch signal sent, that is, to distinguish between human touch recognition and recognition that is consistent with the signal generated by human touch but has different behaviors; further, the difference between human touch recognition and non-human touch recognition lies in the difference in touch area, touch time, touch action, touch strength, effective touch area size, etc.; further, the touch drive circuit part is the original sending signal of the touch signal.

[0013] The beneficial effect of taking the above steps is that further anti-interference of capacitive touch recognition is achieved through active filtering of the touch chip, LFM algorithm filtering, and behavior pattern algorithm filtering.

[0014] Furthermore, the system power supply part is the power supply for the capacitive touch chip; further, the system power supply part has a ripple suppression capability of 95dB; further, the system power supply part has reached level 3 ESD and level 3 EFT through the design for EMC; further, the system power supply part can suppress both differential mode interference and industrial mode interference; further, the system power supply part adopts a low-pass filter, which has sufficient suppression capability for high-frequency noise, avoids the introduction of high-frequency interference signals into the touch chip and ITO, and physically protects the working frequency. Further, the power supply interference signal suppression circuit is composed of a common mode choke, a differential mode capacitor, etc., which filters out high-frequency noise and suppresses power supply ripple.

[0015] The beneficial effect of taking the above steps is that the interference of the power supply through the power supply part of the system includes both common mode interference and differential mode interference. When there is an interference signal, the touch screen will cause drift, false triggering, reduced accuracy, slow response, etc. The power supply interference signal suppression circuit uses a low-pass filter in the touch signal acquisition link to remove high-frequency noise and retain useful touch signal changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of a capacitive touch structure with improved anti-interference capability according to the present invention.

[0017] Figure 2 The present invention is a design diagram of a capacitive touch screen sensor with improved anti-interference performance.

[0018] Figure 3 This is a peak pulse suppression effect diagram of the signal receiving part of the touch chip of a capacitive touch screen with improved anti-interference according to the utility model. DETAILED DESCRIPTION

[0019] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0020] like Figure 1 As shown, a capacitive touch screen with improved anti-interference includes a capacitive touch screen sensor, a touch chip, and a system power supply part, wherein the capacitive touch screen sensor is connected to the touch chip, and the touch chip is connected to the system power supply part; the touch chip includes a receiving part and a transmitting part, and the touch chip receiving part includes a signal receiving part, a touch driving circuit part, and a bandpass filter; the system power supply part includes a power supply part and a power supply interference signal suppression circuit.

[0021] The capacitive touch screen sensor Sensor is connected to the receiving part of the touch chip, that is, the signal receiving part of the touch chip receives the signal returned by the capacitive touch screen sensor Sensor; the capacitive touch screen sensor Sensor is connected to the touch driving circuit part, that is, the touch driving circuit drives the capacitive touch screen sensor Sensor part, so that the Sensor sensing part can effectively perform touch recognition; the system power supply part supplies power to the touch chip, so that it can perform signal triggering, signal recognition, and signal transmission on the basis of electricity.

[0022] In this embodiment, the capacitive touch screen sensor Sensor and its unique ground plane design diagram are as shown in FIG. Figure 2 As shown, the sensor part is centered and the ground plane surrounds the sensor area and is larger than the sensor part.

[0023] Furthermore, the ground plane surrounds the active layer and the inductive layer of the sensor area, but does not form a loop. When there is an interference signal coming from the edge, the surrounding ground plane will play a role in isolating and shielding the interference signal. The low resistance characteristic of the ground plane terminates the interference generated by the interference source at the shielding body made of a good conductor.

[0024] Furthermore, the main function of the touch chip signal receiving part is to receive and amplify the electrical signal generated by the weak capacitance change in the touch area of ​​the capacitive touch screen; further, the touch chip signal receiving part amplifies the electrical signal while performing pulse peak limiting suppression on the amplified signal; further, the touch chip signal receiving part suppresses the pulse peak of the amplified electrical signal and then sends it to a bandpass filter; the operating frequency generated by the non-touch chip transmitting end is filtered out by the bandpass filter, and only the operating frequency range of the touch chip is retained.

[0025] Furthermore, the touch chip signal receiving part recognizes human touch operation behavior based on the signal after bandpass filter processing; further, the touch chip signal receiving part adopts LFM technology, which requires comparison and identification of multi-band digital signals, and adopts digital filtering technology to perform multiple multi-frequency comparison processing on the signal, identify and discard the interference data, and confirm the valid signal again.

[0026] Furthermore, the LFM technology allows the frequency of the carrier signal to change linearly over time; in a linear frequency modulation pulse, the rate of change of the frequency (i.e., the frequency slope) is constant, which means that the instantaneous frequency of the signal increases or decreases linearly over time. Due to the extended spectrum characteristics of the LFM signal, it has a stronger ability to resist narrowband interference to a certain extent compared to a single frequency signal.

[0027] Furthermore, the human touch behavior recognition is to perform intervention recognition on the sent touch signal, that is, to distinguish between human touch recognition and recognition that is consistent with the signal generated by human touch but has different behavior; further, the difference between human touch recognition and non-human touch recognition lies in the difference in touch area, touch time, touch action, touch strength, effective touch area size, etc. Further, the touch drive circuit part is the original transmission signal of the touch signal.

[0028] The beneficial effect of taking the above steps is that further anti-interference of capacitive touch recognition is achieved through active filtering of the touch chip, LFM algorithm filtering, and behavior pattern algorithm filtering.

[0029] Furthermore, the system power supply part is the power supply for the capacitive touch chip; further, the system power supply part has a ripple suppression capability of 95dB; further, the system power supply part has achieved level 3 ESD and level 3 EFT levels through EMC design; further, the system power supply part can suppress both differential mode interference and industrial mode interference; further, the system power supply part adopts a low-pass filter, which has sufficient suppression capability for high-frequency noise, avoids the introduction of high-frequency interference signals into the touch chip and ITO, and physically protects the operating frequency.

[0030] Furthermore, the power supply interference signal suppression circuit is composed of a common mode choke, a differential mode capacitor, etc., which filters out high-frequency noise and suppresses power supply ripple.

[0031] The beneficial effect of taking the above steps is that the interference of the power supply through the power supply part of the system includes both common mode interference and differential mode interference. When there is an interference signal, the touch screen will cause drift, false triggering, reduced accuracy, slow response, etc. The power supply interference signal suppression circuit uses a low-pass filter in the touch signal acquisition link to remove high-frequency noise and retain useful touch signal changes.

[0032] In this specific embodiment, Figure 3 As shown in the figure, typical external interference level pulse interference will interfere with the noise of the capacitive touch receiving part. If it cannot be effectively filtered out, it will produce erroneous signals, which may eventually cause touch recognition abnormalities. The pulse interference can be suppressed by peak pulse limiting suppression.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A capacitive touch screen with improved anti-interference, characterized in that: It includes a capacitive touch screen sensor, a touch chip, and a system power supply part. The capacitive touch screen sensor is connected to the touch chip, and the touch chip is connected to the system power supply part. The touch chip includes a receiving part and a transmitting part. The touch chip receiving part includes a signal receiving part, a touch driving circuit part and a bandpass filter. The system power supply part includes a power supply part and a power interference signal suppression circuit.

2. The capacitive touch screen with improved anti-interference according to claim 1, characterized in that: The capacitive touch screen sensor Sensor is connected to the receiving part of the touch chip, that is, the signal receiving part of the touch chip receives the signal returned by the capacitive touch screen sensor Sensor; the capacitive touch screen sensor Sensor is connected to the touch driving circuit part, that is, the touch driving circuit drives the capacitive touch screen sensor Sensor part; The system power supply part is used to supply power to the touch chip.

3. The capacitive touch screen with improved anti-interference according to claim 1, characterized in that: The architecture of the capacitive touch screen sensor not only includes the necessary ITO wiring, but also includes a ground plane area. The ground plane area is the equipotential area of ​​the capacitive touch screen sensor, which provides a ground plane and a current return path for the ITO. The ground plane area also has EMC performance, and the design area of ​​the ground plane area needs to be larger than the ITO area.

4. The capacitive touch screen with improved anti-interference according to claim 1, characterized in that: The main function of the touch chip signal receiving part is to receive and amplify the electrical signal generated by the weak capacitance change of the touch area of ​​the capacitive touch screen; the touch chip signal receiving part amplifies the electrical signal and suppresses the pulse peak of the amplified signal; the touch chip signal receiving part suppresses the pulse peak of the amplified electrical signal and then sends it to the bandpass filter; The operating frequency generated by the non-touch chip transmitting end is filtered out by a bandpass filter, and only the operating frequency range of the touch chip is retained; the touch chip signal receiving part recognizes human touch operation behavior based on the signal processed by the bandpass filter; the touch chip signal receiving part adopts LFM technology, and the LFM technology allows the frequency of the carrier signal to change linearly with time; the touch drive circuit part is the original sending signal of the touch signal.

5. The capacitive touch screen with improved anti-interference according to claim 1, characterized in that: The system power supply part is the power supply for the capacitive touch chip; the system power supply part has a ripple suppression capability of 95dB; the system power supply part reaches level 3 ESD and level 3 EFT through EMC design; the system power supply part can suppress both differential mode interference and industrial mode interference; the system power supply part adopts a low-pass filter, which has sufficient suppression capability for high-frequency noise; the power supply interference signal suppression circuit is composed of a common-mode choke and a differential-mode capacitor to filter out high-frequency noise and suppress power supply ripple.

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