Multi-chip cascade capacitive touch screen driving system and method

Abstract

The embodiment of the present invention provides a multi-chip cascade capacitive touch screen driving system and method, which belongs to the field of touch technology. The system includes: multiple touch chips, each touch chip is connected to a touch area, and all touch areas are combined to form a complete touch screen; each touch chip is used to process the touch signal of the corresponding connected touch area; the multiple touch chips are connected to a main control chip in parallel, and the working state of each touch chip is coordinated and controlled by the main control chip. The solution of the present invention will not affect the touch response time under the premise of ensuring that the touch chip drive channel meets the driving requirements of a large-size touch screen.

Description

Technical Field

[0001] The present invention relates to the field of touch control technology, and in particular to a multi-chip cascade capacitive touch screen driving system and a multi-chip cascade capacitive touch screen driving method. Background Art

[0002] Capacitive touch screens, with their technical advantages such as supporting multi-touch and sensitive response, are gradually replacing resistive touch screens and are widely used in different fields. As the market demand for capacitive touch screens increases, the size requirements for touch screens are also increasing. As the size of the touch screen increases, higher requirements are placed on the control accuracy and response timeliness of the touch screen. The existing drive device can still meet user needs when processing small-size touch screen signals, but the number of channels of a single capacitive touch chip is limited. As the size of the touch screen becomes larger and larger, a single capacitive touch chip will eventually be unable to meet the demand. Based on the problem that the performance of the existing touch screen drive device is limited and cannot meet the driving needs of the increasingly larger touch screen, it is necessary to create a new capacitive touch screen drive system. Summary of the invention

[0003] The purpose of the embodiments of the present invention is to provide a multi-chip cascade capacitive touch screen driving system and method, so as to at least solve the problem that the existing touch screen driving device has limited performance and cannot meet the driving requirements of touch screens with increasing sizes.

[0004] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a multi-chip cascade capacitive touch screen driving system, the system comprising: multiple touch chips, each touch chip is connected to a touch area, and all touch areas are combined to form a complete touch screen; each touch chip is used to process the touch signal of the corresponding connected touch area; the multiple touch chips are connected in parallel to a main control chip, and the working state of each touch chip is coordinated and controlled by the main control chip.

[0005] Optionally, the system includes 4 touch control chips and corresponding 4 touch control areas.

[0006] Optionally, each touch chip outputs a set of excitation signal channels and is connected to a set of receiving channels; the excitation signal channels and receiving channels of each touch chip are connected to the corresponding touch area; wherein, every two touch chips multiplex a set of receiving channels.

[0007] Optionally, the excitation signal channels of every two touch chips are connected to a two-to-one analog switch, and the two-to-one analog switch is communicatively connected to the main control chip; the main control chip is used to control the alternating output of the excitation signal by controlling the two-to-one analog switch.

[0008] Optionally, after the excitation signal channels of every two touch control chips are connected to a two-to-one analog switch, a group of excitation signal channels are multiplexed at the output end of the switch.

[0009] Optionally, the main control chip is connected to each touch control chip via an I2C interface.

[0010] A second aspect of the present invention provides a multi-chip cascade capacitive touch screen driving method, which is implemented based on the multi-chip cascade capacitive touch screen driving system of the present invention, and includes: each touch chip receives a rising edge signal from the main control chip at a preset interval, and starts to output an excitation signal based on the rising edge signal; each touch chip scans the touch signal of the corresponding touch area based on the excitation signal and a preset working sequence; each touch chip summarizes the touch signals obtained by the scan and transmits them to the main control chip; the main control chip integrates the coordinate position information of the entire touch screen according to the touch signals of each touch chip, and transmits the coordinate position information to the host computer.

[0011] Optionally, each touch chip scans the touch signal of the corresponding touch area based on the excitation signal and the preset working sequence, including: the main control chip controls the switching state of the two-to-one analog switch, including: the main control chip generates two enable control signals, enable control signal one and enable control signal two, for controlling each two-to-one analog switch to work alternately at intervals of a preset switching time: when the enable control signal one is at a low level, the first analog switch of the two-to-one analog switch starts working; when the enable control signal one is at a high level, the first analog switch of the two-to-one analog switch stops working; when the enable control signal two is at a low level, the second analog switch of the two-to-one analog switch starts working; when the enable control signal two is at a high level, the second analog switch of the two-to-one analog switch stops working.

[0012] Optionally, the switching state of the two-to-one analog switch is controlled by the main control chip, and also includes: the main control chip generates two selection signals for controlling the selection of the excitation signal channel of each two-to-one analog switch; according to whether the selection signal is a high level or a low level, the two touch chips connected to each two-to-one analog switch are controlled to be turned on or off respectively.

[0013] On the other hand, the present invention provides a computer-readable storage medium, which stores instructions, and when the instructions are executed on a computer, the computer executes the above-mentioned multi-chip cascade capacitive touch screen driving method.

[0014] Through the above technical solution, multiple touch chips are cascaded to expand the number of drive lines, and a separate main control chip is set to uniformly control the working mode of multiple touch chips. At the same time, a whole large-size touch screen is divided into a corresponding number of equal-sized areas. Each chip is allocated a respective area and scans the touch screen in its respective area. Since the large-size touch screen is divided into multiple small areas and allocated to the corresponding touch chips, and each chip is in charge of its own area, the scanning workload of each touch chip is greatly reduced, and multiple touch chips transmit the touch signal data of their respective areas to the main control chip for integration and processing to merge into a whole area.

[0015] The solution of the present invention does not affect the touch response time under the premise of ensuring that the touch chip driving channel meets the driving requirements of a large-size touch screen.

[0016] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0018] Figure 1 It is a system structure diagram of a multi-chip cascade capacitive touch screen driving system provided by an embodiment of the present invention;

[0019] Figure 2 It is a flowchart of the steps of a multi-chip cascade capacitive touch screen driving method provided by an embodiment of the present invention;

[0020] Figure 3 It is a control signal timing diagram provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0021] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0022] At present, capacitive touch screens can completely replace resistive touch screens with their technical advantages such as supporting multi-touch and sensitive response, and are widely used in different fields. As the market demand for capacitive touch screens increases day by day, the size requirements for touch screens are also increasing. In order to meet the technical requirements for realizing airborne domestic large-size capacitive touch screens, this patent proposes a method of cascading multiple touch chips to drive large-size capacitive touch screens. Since the number of channels of a domestic capacitive touch chip on the market cannot meet the requirements of driving a large-size capacitive touch screen, the present invention uses multiple domestic touch chips for cascading to effectively expand the number of drive lines. One of the technical difficulties faced by multi-chip driving is the working timing control between multiple chips. For this reason, a separate main control chip MCU is also required to uniformly control the working mode of multiple touch chips, and at the same time divide a whole large-size touch screen into multiple areas of equal size, each chip is allocated a respective area, and the touch screen in its respective area is scanned. Since the large-size touch screen is divided into multiple small areas and assigned to multiple touch chips, each chip is responsible for its own area, so the scanning workload of each touch chip is greatly reduced. The multiple touch chips transmit the touch signal data of their respective areas to the MCU for integration and processing to merge into a whole area. This patented method will not have a significant impact on the touch response time and can meet the touch response time requirements.

[0023] Figure 1 FIG. 1 is a system structure diagram of a multi-chip cascade capacitive touch screen driving system provided by an embodiment of the present invention. Figure 1 As shown, an embodiment of the present invention provides a multi-chip cascade capacitive touch screen driving system, the system comprising:

[0024] Multiple touch chips, each touch chip is connected to a touch area, and all touch areas are combined to form a complete touch screen; each touch chip is used to process the touch signal of the corresponding connected touch area; the multiple touch chips are connected in parallel to a main control chip; the main control chip is used to coordinate and control the working status of each touch chip.

[0025] In a possible implementation, the touch screen sensor excitation signal channel (TX) and receiving channel (RX) are evenly distributed to four touch chips A, B, C, and D, and the touch screen sensor receiving channel RX is evenly divided into two parts. The RX channels of regions 1 and 2 are connected to touch chips A and B, such as Figure 1 As shown, RX1 and RX2 are short-circuited for reuse. The RX channels of regions 3 and 4 are connected to touch control chips C and D, as shown in Figure 1As shown, RX3 and RX4 are short-circuited for reuse. The touch screen sensor excitation signal channel TX is also divided into two parts. Areas 1 and 3 are connected to touch chips A and C, and areas 2 and 4 are connected to touch chips B and D. If the excitation signal lines are directly short-circuited, it may affect the excitation signal, so a two-choice analog switch is added to the TX1 and TX3 and TX2 and TX4 excitation channels. The MCU sends a selection control signal to control the two-choice analog switch, so that the excitation signals TX1 to TX4 of the four touch chips work alternately to output excitation signals in turn, and there is no interference between them.

[0026] Preferably, the system includes 4 touch control chips and corresponding 4 touch control areas.

[0027] In the embodiment of the present invention, in theory, the more touch chips there are, the higher the processing efficiency of each area of ​​the touch screen will be. However, the more touch chips there are, the more load-intensive the timing control method is, which greatly increases the failure rate. And because of the timing control characteristics of each touch chip, if the number of touch chips is increased infinitely, the touch delay will become larger and larger, which will reduce the user experience. Finally, if the number of touch chips is increased infinitely, more installation space for touch chips will be required, which will increase the size of the device, which is contrary to the current development law of convenient devices. Therefore, in order to avoid the above situation, it is preferred that the number of touch chips is selected to be 4, and the touch screen is divided into 4 areas accordingly. The upgraded device takes into account the timeliness of response, convenience and low failure rate. For example, four domestically produced touch chips A, B, C, D, and another separate main control chip MCU are selected to form a cascade system. A whole large-sized capacitive touch screen is divided into four areas of equal size, which are respectively allocated to four touch chips, and each chip is responsible for its own quarter area. The four touch chips are uniformly controlled by the MCU, which sends control signals to the four chips to control the operation of each touch chip. The four touch chips work alternately under the control of the MCU. The four touch chips transmit the touch signal data scanned in their respective areas to the MCU via the I2C interface, and the MCU integrates and processes the data to obtain the touch coordinate position data of the entire touch screen and transmits it to the host computer. The touch signal data can be viewed and the touch line can be debugged through the host computer debugging software.

[0028] Preferably, each touch chip outputs a set of excitation signal channels and accesses a set of receiving channels; the excitation signal channels and receiving channels of each touch chip are connected to the corresponding touch area; wherein, every two touch chips multiplex a set of receiving channels.

[0029] Specifically, because there are four touch chips in this solution, the chip connection lines and chip installation positions pose a great challenge to traditional touch screen devices. While increasing the number of chips and the number of loops, the volume of the existing touch screen device cannot be increased wirelessly. With the deepening of intelligence, under the premise of pursuing convenience and comprehensive control, the volume and weight of the device itself need to be smaller and smaller, and the lightweight device is increasingly valued by people. Therefore, based on the timing control characteristics of the four touch chips, preferably, one receiving channel is reused for every two touch chips. This can reduce the number of line channels, which not only saves line usage and simplifies the circuit, but also saves device space, and avoids the device being too large, resulting in a decrease in user experience.

[0030] Preferably, the excitation signal channels of every two touch chips are connected to a two-to-one analog switch, and the two-to-one analog switch is communicatively connected to the main control chip; the main control chip is used to control the alternating output of the excitation signal by controlling the two-to-one analog switch.

[0031] In the embodiment of the present invention, in order to simplify the control loop and reduce the use of lines, the excitation signals are sent alternately according to the timing control performance of each touch chip, and only one touch chip works in the line at the same time. A two-to-one analog switch is set at the output end of the excitation signal of every two touch chips. When the excitation signal of a touch chip is selected, the excitation signal path of the other touch chip is closed. In order to improve the use efficiency of the line, a two-to-one analog switch is set to select the line to determine, ensure that only one touch chip signal is transmitted on the line at the same time, and realize the working control of two touch chips through one line.

[0032] Preferably, after the excitation signal channels of every two touch control chips are connected to a two-to-one analog switch, a signal excitation channel is multiplexed at the output end of the switch.

[0033] In the embodiment of the present invention, similar to the receiving channel, after every two touch chips pass through the two-to-one analog switch, a signal excitation channel is multiplexed at the switch output end. The MCU sends a selection control signal to control the two-to-one analog switch, so that the two touch chips on one analog switch output the excitation signal alternately, and there is no interference between them.

[0034] Preferably, the main control chip is connected to each touch control chip via an I2C interface.

[0035] In the embodiment of the present invention, because the scheme of the present invention is that one master chip corresponds to multiple touch control chips, the master device and slave device required for I2C bus communication are adapted. In I2C bus communication, the master device is used to start the bus to transmit data and generate a clock to open the device for transmission. At this time, any addressed device is considered to be a slave device. The relationship between the master and the slave, the send and the receive on the bus is not constant, but depends on the data transmission direction at this time. I2C bus communication has significant simplicity and effectiveness, which is exactly adapted to the effect required by the scheme of the present invention, that is, it ensures the singleness of signal transmission, avoids mutual interference between the touch control chips, and reduces the failure rate of the device due to simplicity.

[0036] Figure 2 FIG. 1 is a method flow chart of a multi-chip cascade capacitive touch screen driving method provided by an embodiment of the present invention. Figure 2 As shown, an embodiment of the present invention provides a multi-chip cascade capacitive touch screen driving method, the method comprising:

[0037] Step S10: each touch control chip receives a rising edge signal from the main control chip at a preset interval, and starts to output an excitation signal based on the rising edge signal.

[0038] Specifically, the four touch chips A, B, C, and D all work under the control of the MCU. Each of the four touch chips has an IO port (GPIO1 to GPIO4) connected to the MCU chip. The MCU chip will provide each chip with a rising edge enable control signal with a preferred interval of 20ms at a preset interval (preferably 5ms). When the IO port of the touch chip receives the rising edge signal, it starts to output the excitation signal and scan the capacitive touch signal of its respective area.

[0039] Step S20: each touch chip starts scanning the touch signal of the corresponding touch area based on the excitation signal and the preset working sequence.

[0040] Specifically, the four touch chips A, B, C, and D work alternately in the order of ACBD under the coordinated control of the MCU. The specific working order is related to the control of the two-choice analog switch state, which is executed by the main control chip. The specific execution rules are to generate two enable control signals for the main control chip to control each two-choice analog switch to work alternately at a preset switch time interval; when the enable control signal 1 is at a low level, the first analog switch starts working; when the enable control signal 1 is at a high level, the first analog switch stops working; when the enable control signal 2 is at a low level, the second analog switch starts working; when the enable control signal 2 is at a high level, the second analog switch stops working.

[0041] In a possible implementation, Figure 3, MCU controls two two-to-one analog switches K1 and K2. MCU outputs enable control signals EN1 and EN2 to control the two two-to-one analog switches K1 and K2 to work alternately every 10ms. When EN1 is at a low level, the two-to-one analog switch K1 starts working, and when the level is high, K1 stops working. When EN2 is at a low level, the two-to-one analog switch K2 starts working, and when the level is high, K2 stops working. The EN signal waveform is shown in Figure 3. The EN1 and EN2 signals are opposite to each other, so that the two two-to-one analog switches K1 and K2 work alternately every 10ms.

[0042] At the same time, if Figure 3 , the MCU outputs selection signal 1 and selection signal 2 to two two-to-one analog switches respectively. When the selection signal 1 is low, the excitation signal channel TX1 of the touch chip A is turned on to output the excitation signal. When the selection signal 1 is high, the excitation signal channel TX3 of the touch chip C is turned on to output the excitation signal. When the selection signal 2 is low, the excitation signal channel TX2 of the touch chip B is turned on to output the excitation signal. When the selection signal 2 is high, the excitation signal channel TX4 of the touch chip D is turned on to output the excitation signal. Under the control of the enable signal EN and the selection signal output by the MCU, the four touch chips output the excitation signals alternately in the order of TX1-TX3-TX2-TX4 during the entire working cycle.

[0043] Step S30: each touch control chip collects and transmits the touch signals obtained by scanning to the main control chip.

[0044] Specifically, the four touch chips work in sequence under the control of the MCU, respectively scanning the capacitive touch signals of the touch screen in their respective areas, and transmitting the scanned touch signal data of the four areas to the MCU through the I2C interface.

[0045] Specifically, the main control chip integrates and obtains the coordinate position information of the entire touch screen according to the touch signals of each touch chip, and transmits the coordinate position information to the host computer.

[0046] Specifically, the MCU finally integrates the touch data of the four areas into the coordinate position information of an entire area, and transmits the coordinate position information to the host computer. The touch signal data of each area can be viewed through the host computer debugging software, and a line drawing test can be performed, which is convenient for maintenance and debugging when a capacitive touch screen fails.

[0047] In an embodiment of the present invention, a large-sized capacitive touch screen is divided into four equal-sized areas, and the four areas are allocated to four touch chips for cascade driving, and each touch chip is responsible for its own area. The four touch chips do not need to be interconnected by the method of this patent, so there is no need to consider the timing synchronization problem of the four chips, which effectively overcomes the difficulty of timing unification during cascade operation. At the same time, the four touch chips only need to coordinate and work in sequence under the control of the MCU. During the entire scanning cycle, only one of the four touch chips is required to send the excitation signal and scan the touch signal data, which solves the interference problem between different touch chips during cascade operation, making the system run more stable. The four touch chips only need to transmit the touch signal data scanned in their respective areas to the MCU, so it will not affect the touch response time of the touch chip, and reduce the consumption of internal resources occupied by each touch chip. The touch signal data is mainly integrated and processed by the MCU for the touch signal data of the four areas, so it will not have much impact on the touch response time, ensuring that the touch response time of the touch screen meets the touch requirements.

[0048] The embodiment of the present invention further provides a computer-readable storage medium, on which instructions are stored, which, when executed on a computer, enable the computer to execute the above-mentioned multi-chip cascade capacitive touch screen driving method.

[0049] Those skilled in the art will understand that all or part of the steps in the method for implementing the above-mentioned embodiments can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including several instructions for making a single-chip microcomputer, a chip or a processor (processor) perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0050] The optional embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the technical concept of the embodiments of the present invention, the technical scheme of the embodiments of the present invention can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the embodiments of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0051] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A multi-chip cascade capacitive touch screen driving system, characterized in that: The system comprises: Multiple touch chips, each touch chip is connected to a touch area, and all touch areas are combined to form a complete touch screen; each touch chip is used to process the touch signal of the corresponding connected touch area; The multiple touch control chips are connected in parallel to a main control chip, and the working state of each touch chip is coordinated and controlled by the main control chip; The system includes 4 touch control chips and corresponding 4 touch control areas; The excitation signal channels of every two touch control chips are connected to a two-to-one analog switch, and the two-to-one analog switch is communicatively connected to the main control chip; The main control chip is used to control the alternate output of the excitation signal by controlling the two-choice analog switch; Each touch control chip receives a rising edge signal from the main control chip at a preset interval, and starts to output an excitation signal based on the rising edge signal; Each touch chip scans the touch signal of the corresponding touch area based on the excitation signal and the preset working sequence; wherein, Each touch chip scans the touch signal of the corresponding touch area based on the excitation signal and the preset working order, including: The main control chip controls the switching state of the two-choice analog switch, including: The main control chip generates two enable control signals, enable control signal 1 and enable control signal 2, which are used to control each two-choice analog switch to work alternately at a preset switching time interval: When the enable control signal 1 is at a low level, the first analog switch of the two-to-one analog switch starts to work; When the enable control signal 1 is at a high level, the first analog switch of the two-to-one analog switch stops working; When the second enable control signal is at a low level, the second analog switch of the two-to-one analog switch starts to work; When the second enable control signal is at a high level, the second analog switch of the two-to-one analog switch stops working; The main control chip controls the switch state of the two-choice analog switch, and further includes: The main control chip generates two selection signals for controlling the selection of the excitation signal channel of each two-to-one analog switch; According to whether the selection signal is at a high level or a low level, the two touch control chips connected to each two-to-one analog switch are controlled to be turned on or off respectively.

2. The system according to claim 1, characterized in that Each touch chip outputs a set of excitation signal channels and accesses a set of receiving channels; The excitation signal channel and receiving channel of each touch chip are connected to the corresponding touch area; Among them, every two touch control chips multiplex a group of receiving channels.

3. The system according to claim 1, characterized in that After the excitation signal channels of every two touch chips are connected to a two-to-one analog switch, a group of excitation signal channels are multiplexed at the output end of the switch.

4. The system according to claim 1, characterized in that The main control chip is connected to each touch control chip via an I2C interface.

5. A multi-chip cascade capacitive touch screen driving method, characterized in that: The method is implemented based on the multi-chip cascade capacitive touch screen driving system according to any one of claims 1 to 4, and the method comprises: Each touch control chip receives a rising edge signal from the main control chip at a preset interval, and starts to output an excitation signal based on the rising edge signal; Each touch chip scans the touch signal of the corresponding touch area based on the excitation signal and the preset working order; Each touch chip collects and transmits the touch signals obtained by scanning to the main control chip; The main control chip integrates the touch signals of each touch chip to obtain the coordinate position information of the entire touch screen, and transmits the coordinate position information to the host computer.

6. A computer-readable storage medium having instructions stored thereon, which, when executed on a computer, enables the computer to execute the multi-chip cascade capacitive touch screen driving method according to claim 5.

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