Fully-isolated touch screen USB interface circuit
By using a fully isolated touchscreen USB interface circuit, utilizing optocoupler units and isolated power supply modules, signal symmetry is optimized, the impact of internal interference on the USB interface is resolved, and automatic identification and isolation of USB transmission is achieved.
Patent Information
- Application Number
- CN202422711018.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-12-19
- Estimated Expiration
- 2034-11-07
AI Technical Summary
In existing touchscreen USB interface circuits, common-mode and differential-mode interference within the device can affect the USB interface transmission path during signal transmission, resulting in incomplete isolation. Additional filtering or signal conditioning circuits are required to reduce the impact.
The touchscreen USB interface circuit is fully isolated, including upper and lower isolation control modules. Through the isolation power supply module, the symmetry of the optocoupler output signal is optimized by using the optocoupler unit and the second optocoupler unit, so as to achieve effective isolation between signal and power.
It achieves automatic identification of USB transfer speed, is a pure hardware solution, and features a completely real-time and transparent USB protocol that does not require additional filtering or signal conditioning circuits, effectively isolating common-mode and differential-mode interference within the device.
Smart Images
Figure CN223692743U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to communication circuit technical field, concretely relates to full isolation's touch -sensitive screen USB interface circuit. BACKGROUND
[0002] Touch -sensitive screen USB interface circuit is continuously improved in modern electronic equipment to the requirement of user interactive experience, and touch -sensitive screen is widely used in mobile phone, tablet computer and self -service terminal etc. as the direct input mode, touch -sensitive screen can realize fast, stable data transmission and power supply through USB interface, simplifies the connection mode, and enhances the compatibility of equipment. Its significance lies in improving user operation convenience, promoting the popularization and development of intelligent equipment, and simultaneously promoting the innovation and application of touch -sensitive technology.
[0003] The existing touch -sensitive screen USB interface circuit when carrying out signal transmission, the device internal common mode and difference mode can interfere with the path of USB interface transmission, usually needs the additional filter or signal conditioning circuit to reduce its influence, is difficult to ensure the real -time and transparency of USB protocol, and even leads to its isolation not thoroughly, and for this, full isolation's touch -sensitive screen USB interface circuit is provided to solve the above -mentioned problem. UTILITY MODEL CONTENTS
[0004] To solve above -mentioned technical problem, provide full isolation's touch -sensitive screen USB interface circuit, and the present technical scheme solves the problem that the existing touch -sensitive screen USB interface circuit when carrying out signal transmission, the device internal common mode and difference mode can interfere with the path of USB interface transmission, usually needs the additional filter or signal conditioning circuit to reduce its influence in the background art.
[0005] To reach above -mentioned purpose, the utility model adopts the technical scheme for:
[0006] Full isolation's touch -sensitive screen USB interface circuit, comprising:
[0007] Computer module, the computer module sends USB bus data positive, data negative signal;
[0008] The upper isolation control module receives the USB bus data positive, data negative signal sent by the computer module;
[0009] The upper isolation control module comprises an upper isolation control chip and a first connector, the first connector is provided with an open port for connecting a computer and a computer module, the upper isolation control chip shares a power supply with the computer through the first connector, first and second pins of the upper isolation control chip are electrically connected with a second voltage transient suppression diode and a first voltage transient suppression diode respectively, and the first and second voltage transient suppression diodes are used for protection of a communication line and are connected in parallel between USB bus data positive, data negative and a power supply ground pole respectively, a third pin of the upper isolation control chip is electrically connected with a third capacitor, a fourth pin of the first connector is electrically connected with a first capacitor and a second capacitor, and the first, second and third capacitors are all power supply decoupling capacitors.
[0010] Optionally, the touch screen control module outputs USB bus data positive and data negative signals and transmits the signals to the lower isolation control module, the lower isolation control module outputs two-way signal to drive the second optoelectronic coupling unit, the second optoelectronic coupling unit outputs a logic positive signal and a logic negative signal and transmits the signals to the upper isolation control module, and the upper isolation control module outputs USB bus data positive and negative signals to the computer module after receiving the logic positive signal and the logic negative signal.
[0011] Optionally, a power supply positive pole and a power supply ground pole of the computer module are input to the upper isolation control module, and the computer module is electrically connected with an input end of an isolation power supply module, the isolation power supply module outputs an isolated power supply positive pole and a power supply ground pole and is electrically connected with the lower isolation control module, and the isolation power supply module is electrically connected with the touch screen control module.
[0012] Optionally, the upper isolation control module is built-in with the first optoelectronic coupling unit, and the upper isolation control module outputs two-way signal to drive the first optoelectronic coupling unit.
[0013] The first optoelectronic coupling unit is composed of an infrared light emitting diode and a photosensitive detection integrated circuit, the first optoelectronic coupling unit outputs isolated logic positive and negative signals and is electrically connected with the lower isolation control module, and the lower isolation control module outputs USB bus data positive and negative signals to the touch screen control module.
[0014] Optionally, the lower isolation control module comprises a lower isolation control chip and a second connector, the second connector is open to a port for connecting the touch screen control module, a first pin and a second pin of the lower isolation control chip are electrically connected with a fourth voltage transient suppression diode and a third voltage transient suppression diode respectively, the fourth voltage transient suppression diode and the third voltage transient suppression diode are used for protection of a communication line, and the third voltage transient suppression diode and the fourth voltage transient suppression diode are connected in parallel between a USB bus data positive, a data negative and a power supply ground pole respectively, a third pin of the lower isolation control chip is electrically connected with a twentieth capacitor, a second pin of the lower isolation control chip is electrically connected with an eighteenth capacitor and a nineteenth capacitor, and the eighteenth capacitor, the nineteenth capacitor and the twentieth capacitor are all power supply decoupling capacitors, and an eleventh pin of the lower isolation control chip is electrically connected with an anode of a first light emitting diode through a ninth resistor.
[0015] Optionally, the upper isolation control module and the lower isolation control module are provided with a first optoelectronic coupling unit and a second optoelectronic coupling unit, the first optoelectronic coupling unit comprises a sixth isolation chip and a fifth isolation chip, a second pin and a third pin of the fifth isolation chip are electrically connected with a thirteenth capacitor, a third pin of the fifth isolation chip is connected in series with a fifth resistor, a fifth pin and a sixth pin of the fifth isolation chip are electrically connected with a fourteenth capacitor and a sixth resistor respectively, a second pin and a third pin of the sixth isolation chip are electrically connected with a thirteenth capacitor, a third pin of the sixth isolation chip is connected in series with a seventh resistor, a fifth pin and a sixth pin of the sixth isolation chip are electrically connected with a sixteenth capacitor and an eighth resistor respectively.
[0016] Optionally, the second optoelectronic coupling unit comprises a third isolation chip and a second isolation chip, a second pin and a third pin of the second isolation chip are electrically connected with a fourth capacitor, a third pin of the second isolation chip is connected in series with a first resistor, a fifth pin and a sixth pin of the second isolation chip are electrically connected with a fifth capacitor and a second resistor respectively, a second pin and a third pin of the third isolation chip are electrically connected with a sixth capacitor, a third pin of the third isolation chip is connected in series with a third resistor, a fifth pin and a sixth pin of the third isolation chip are electrically connected with a seventh capacitor and a fourth resistor respectively.
[0017] Optionally, the first optoelectronic coupling unit and the second optoelectronic coupling unit optimize the symmetry between rising edges and falling edges of an optocoupler output signal by adjusting the fifth resistor, the thirteenth capacitor, the seventh resistor, the fifteenth capacitor, the first resistor, the fourth capacitor, the third resistor and the sixth capacitor, the fifth capacitor, the seventh capacitor, the fourteenth capacitor and the sixteenth capacitor are all decoupling capacitors, and the second resistor, the fourth resistor, the sixth resistor and the eighth resistor are all optocoupler output end pull-up resistors.
[0018] Optionally, the fourth pin of the first connector in the upper isolation control module is connected to an isolation power module through a pi filter circuit, the isolation power module comprises an isolation power chip, a first pin of the isolation power chip is electrically connected to the fourth pin of the first connector in the upper isolation control module, the pi filter circuit is composed of an eighth capacitor, a ninth capacitor, a tenth capacitor and a first inductor, a second pin of the isolation power chip is electrically connected to a power supply ground pole of the computer module, a fifth pin of the isolation power chip is electrically connected to a power supply ground pole of the touch control module, the second pin and the fifth pin of the isolation power chip are electrically connected with a seventeenth capacitor, a seventh pin of the isolation power chip outputs an isolated power supply, and the first pin of the isolation power chip is electrically connected with an eleventh capacitor and a twelfth capacitor.
[0019] Compared with the prior art, the utility model has the advantages that:
[0020] In the full-isolated touch screen USB interface circuit, the LSI# pin of the isolation control chip is used as the input pin for selecting the USB transmission speed, the low level input is 1.5 Mbps of the USB low speed, and the high level input is 12 Mbps of the USB full speed; the LSO# pin of the isolation control chip is used as the output pin for automatically detecting the USB transmission speed, the low level output is 1.5 Mbps of the USB low speed, and the high level output is 12 Mbps of the USB full speed, so that the automatic identification of the USB speed is realized, the pure hardware solution is adopted, the USB protocol is completely real-time and transparent, no additional filtering or signal conditioning circuit is needed to reduce the influence, and the device internal common mode and differential mode interference is effectively isolated from the USB interface transmission path in terms of signal and power.
[0021] In the full-isolated touch screen USB interface circuit and method, the photoelectric coupler in the first photoelectric coupling unit and the second photoelectric coupling unit is used to reduce the influence of electromagnetic field interference in the working environment, the parameters of the first resistor, the fourth capacitor, the third resistor, the sixth capacitor, the fifth resistor, the thirteenth capacitor, the seventh resistor and the fifteenth capacitor are adjusted to optimize the symmetry between the rising edge and the falling edge of the photoelectric coupling output signal, and the influence of the speed and speed symmetry of the photoelectric coupler on the signal delay and balance is reduced. BRIEF DESCRIPTION OF DRAWINGS
[0022] Figure 1 The module block diagram of the full-isolated touch screen USB interface circuit is provided in the utility model;
[0023] Figure 2 The principle diagram of the upper computer isolation control circuit in the utility model is provided;
[0024] Figure 3The principle diagram of the lower computer isolation control circuit in the utility model;
[0025] Figure 4 The principle diagram of the first photoelectric coupling unit in the utility model;
[0026] Figure 5 The principle diagram of the second photoelectric coupling unit in the utility model;
[0027] Figure 6 The principle diagram of the isolation power module in the utility model. DETAILED DESCRIPTION
[0028] The following description is used to disclose the utility model so that those skilled in the art can realize the utility model. The preferred embodiments in the following description are only as examples, and other obvious variants can be thought of by those skilled in the art.
[0029] Referring to Figure 1 - Figure 6 As shown in the figure, the full-isolation touch screen USB interface circuit comprises:
[0030] A computer module, which sends USB bus data positive and negative signals;
[0031] An upper isolation control module, which receives the USB bus data positive and negative signals (USB_D+, USB_D-) sent by the computer module;
[0032] The upper isolation control module comprises an upper isolation control chip U1 and a first connector J1, the first connector J1 is provided with an open port for connecting the computer and the computer module, the upper isolation control chip U1 shares a power supply with the computer through the first connector J1, the first pin and the second pin of the upper isolation control chip U1 are electrically connected with a second voltage transient suppression diode TVS2 and a first voltage transient suppression diode TVS1 respectively, and the first voltage transient suppression diode TVS1 and the second voltage transient suppression diode TVS2 are used for protecting the communication line and are connected in parallel between the USB bus data positive and negative and the power supply ground, the third pin of the upper isolation control chip U1 is electrically connected with a third capacitor C3, the fourth pin of the first connector J1 is electrically connected with a first capacitor C1 and a second capacitor C2, and the first capacitor C1, the second capacitor C2 and the third capacitor C3 are all power decoupling capacitors.
[0033] Further, the touch screen control module outputs USB bus data positive and negative signals and transmits them to the lower isolation control module, the lower isolation control module outputs two signals to drive the second optocoupler unit, the second optocoupler unit outputs logic positive and negative signals and transmits them to the upper isolation control module, and the upper isolation control module outputs USB bus data positive and negative signals to the computer module after receiving the logic positive and negative signals.
[0034] It can be understood that the touch screen control module is provided with a fully isolated touch screen USB interface circuit, supports 12Mbps full-speed USB transmission and 1.5Mbps low-speed USB transmission, is compatible with USB V2.0, can automatically identify USB full-speed or USB low-speed, and provides USB transmission state indication. The pure hardware solution is completely real-time and transparent to the USB protocol, and does not require any additional installation of a driver. The device internal common mode and differential mode interference is effectively isolated from the transmission path through the USB interface. The solution provides a solution to the touch jump point problem of the ruggedized touch all-in-one device.
[0035] Further, the power positive and power ground poles of the computer module are input to the upper isolation control module, and the computer module is electrically connected to the input end of the isolation power module, the isolation power module outputs isolated power positive and power ground poles and is electrically connected to the lower isolation control module, and the isolation power module is electrically connected to the touch screen control module.
[0036] Further, the lower isolation control module includes a lower isolation control chip U7 and a second connector J2, the second connector J2 is provided with a port for connecting the touch screen control module, the first and second pins of the lower isolation control chip U7 are respectively electrically connected with a fourth voltage transient suppression diode TVS4 and a third voltage transient suppression diode TVS3, the fourth voltage transient suppression diode TVS4 and the third voltage transient suppression diode TVS3 are used for communication line protection, and the third voltage transient suppression diode TVS3 and the fourth voltage transient suppression diode TVS4 are respectively connected in parallel between the USB bus data positive and negative and the power ground pole, the third pin of the lower isolation control chip U7 is electrically connected with a twentieth capacitor C20, the second pin of the lower isolation control chip U7 is electrically connected with an eighteenth capacitor C18 and a nineteenth capacitor C19, and the eighteenth capacitor C18, the nineteenth capacitor C19 and the twentieth capacitor C20 are all power decoupling capacitors, and the eleventh pin of the lower isolation control chip U7 is electrically connected with the anode of a first light-emitting diode LED1 through a ninth resistor.
[0037] Further, the first optoelectronic coupling unit and the second optoelectronic coupling unit are arranged between the upper isolation control module and the lower isolation control module, the first optoelectronic coupling unit comprises a sixth isolation chip U6 and a fifth isolation chip U5, the second pin and the third pin of the fifth isolation chip U5 are electrically connected with a thirteenth capacitor C13, and the third pin of the fifth isolation chip U5 is connected in series with a fifth resistor R5, the fifth pin and the sixth pin of the fifth isolation chip U5 are electrically connected with a fourteenth capacitor C14 and a sixth resistor R6 respectively, the second pin and the third pin of the sixth isolation chip U6 are electrically connected with the thirteenth capacitor C13, and the third pin of the sixth isolation chip U6 is connected in series with a seventh resistor R7, the fifth pin and the sixth pin of the sixth isolation chip U6 are electrically connected with a sixteenth capacitor C16 and an eighth resistor R8 respectively.
[0038] Further, the second optoelectronic coupling unit comprises a third isolation chip U3 and a second isolation chip U2, the second pin and the third pin of the second isolation chip U2 are electrically connected with a fourth capacitor C4, and the third pin of the second isolation chip U2 is connected in series with a first resistor R1, the fifth pin and the sixth pin of the second isolation chip U2 are electrically connected with a fifth capacitor C5 and a second resistor R2 respectively, the second pin and the third pin of the third isolation chip U3 are electrically connected with a sixth capacitor C6, and the third pin of the third isolation chip U3 is connected in series with a third resistor R3, the fifth pin and the sixth pin of the third isolation chip U3 are electrically connected with a seventh capacitor C7 and a fourth resistor R4 respectively.
[0039] Further, the first optoelectronic coupling unit and the second optoelectronic coupling unit optimize the symmetry between the rising edge and the falling edge of the optocoupler output signal by adjusting the fifth resistor R5, the thirteenth capacitor C13, the seventh resistor R7, the fifteenth capacitor C15, the first resistor R1, the fourth capacitor C4, the third resistor R3 and the sixth capacitor C6, the fifth capacitor C5, the seventh capacitor C7, the fourteenth capacitor C14 and the sixteenth capacitor C16 are all decoupling capacitors, and the second resistor R2, the fourth resistor R4, the sixth resistor R6 and the eighth resistor R8 are all pull-up resistors of the optocoupler output terminal.
[0040] Specifically, the model of the optocoupler can be selected as a single-channel or double-channel high-speed optocoupler. An optocoupler with a transmission rate greater than 10 Mbit is selected for the isolation of a 12 Mbps full-speed USB signal. The speed and speed symmetry of the optocoupler are considered to affect the signal delay and balance. By adjusting the parameters of the first resistor R1 / fourth capacitor C4, the third resistor R3 / sixth capacitor C6, the fifth resistor R5 / thirteenth capacitor C13, the seventh resistor R7 / fifteenth capacitor C15, the symmetry between the rising edge and the falling edge of the optocoupler output signal is optimized.
[0041] Further, the fourth pin of the first connector J1 in the upper isolation control module is connected to the isolation power module through a π-type filter circuit, the isolation power module includes an isolation power chip U4, the first pin of the isolation power chip U4 is electrically connected to the fourth pin of the first connector J1 in the upper isolation control module, the π-type filter circuit is composed of an eighth capacitor C8, a ninth capacitor C9, a tenth capacitor C10 and a first inductor L1, the second pin of the isolation power chip U4 is electrically connected to the power supply ground of the computer module, the fifth pin of the isolation power chip U4 is electrically connected to the power supply ground of the touch control module, and the second pin and the fifth pin of the isolation power chip U4 are electrically connected with a seventeenth capacitor C17, the seventh pin of the isolation power chip U4 outputs an isolated power supply, and the first pin of the isolation power chip U4 is electrically connected with an eleventh capacitor C11 and a twelfth capacitor C12.
[0042] Further, the upper isolation control module is built-in a current drive circuit of a first optoelectronic coupling unit, and outputs two-way signals (OPOP_PC, OPON_PC) to drive the first optoelectronic coupling unit. The first optoelectronic coupling unit is composed of a GaAsP infrared light emitting diode with high emission intensity and a high-speed high-gain photosensitive detection integrated circuit, and the first optoelectronic coupling unit and a second optoelectronic coupling unit can be two single-way or one double-way optoelectronic couplers, and the optoelectronic couplers will not be affected by electromagnetic field interference in the working environment. The LSI# pin of the upper isolation control chip U1 and the lower isolation control chip U7 in the upper isolation control module is a USB transmission speed selection input pin, the input low level is USB low speed 1.5 Mbps, and the input high level is USB full speed 12 Mbps. The LSO# pin of the upper isolation control chip U1 and the lower isolation control chip U7 is a USB transmission speed automatic detection result output pin, the output low level is USB low speed 1.5 Mbps, and the high level is USB full speed 12 Mbps. In the example, the LSI# pin in the upper isolation control chip U1 and the lower isolation control chip U7 is directly connected to the LSO# pin, so as to realize automatic recognition of the USB speed. If only a certain speed needs to be supported, the LSI# can be directly forced to be low or high level.
[0043] Specifically, the UP# pin of the lower isolation control chip U7 is a mode selection input, built-in pull-up resistor, and connected to a 5V power supply (high level) to be in the lower machine mode. The ACT# pin of the lower isolation control chip U7 is a USB transmission state output, and the low level is valid, built-in pull-up resistor, series-connected ninth resistor R9 current limiting resistor, and then connected to LED1 light emitting diode, which is used to indicate the USB transmission state.
[0044] The basic principle, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection required by the present application is defined by the appended claims and their equivalents.
Claims
1. A fully isolated touch screen USB interface circuit, characterized in that, The application relates to a computer module, an upper isolation control module, a touch screen control module and a lower isolation control module. The computer module sends USB bus data positive and negative signals. The upper isolation control module receives the USB bus data positive and negative signals sent by the computer module. The touch screen control module outputs USB bus data positive and negative signals and transmits the signals to the lower isolation control module. The lower isolation control module outputs two-way signal to drive the second photoelectric coupling unit.
2. The fully isolated touch screen USB interface circuit of claim 1, wherein, The second photoelectric coupling unit outputs logic positive and negative signals and transmits the signals to the upper isolation control module. The upper isolation control module outputs USB bus data positive and negative signals to the computer module after receiving the logic positive and negative signals.
3. The fully isolated touch screen USB interface circuit of claim 1, wherein, The upper isolation control module comprises an upper isolation control chip and a first connector. The first connector is provided with an open port for connecting the computer and the computer module. The upper isolation control chip shares a power supply with the computer through the first connector.
4. The fully isolated touch screen USB interface circuit of claim 3, wherein, The first pin and the second pin of the upper isolation control chip are respectively electrically connected with a second voltage transient suppression diode and a first voltage transient suppression diode. The first voltage transient suppression diode and the second voltage transient suppression diode are used for protecting a communication line and are respectively connected in parallel between the USB bus data positive and negative signals and the power supply ground. The third pin of the upper isolation control chip is electrically connected with a third capacitor. The fourth pin of the first connector is electrically connected with a first capacitor and a second capacitor. The first capacitor, the second capacitor and the third capacitor are all power decoupling capacitors. Specifically, The power positive pole and the power ground of the computer module are input into the upper isolation control module. The computer module is electrically connected with the input end of an isolation power supply module. The isolation power supply module outputs an isolated power positive pole and a power ground and is electrically connected with the lower isolation control module. The isolation power supply module is electrically connected with the touch screen control module. Specifically, The upper isolation control module is internally provided with a first photoelectric coupling unit. The upper isolation control module outputs two-way signals to drive the first photoelectric coupling unit. The first photoelectric coupling unit is composed of an infrared light emitting diode and a photosensitive detection integrated circuit. The first photoelectric coupling unit outputs the isolated logic positive and negative signals and is electrically connected with the lower isolation control module. The lower isolation control module outputs USB bus data positive and negative signals to the touch screen control module. Specifically, The lower isolation control module includes a lower isolation control chip and a second connector, the second connector is open to connect the port of the touch screen control module, the first pin and the second pin of the lower isolation control chip are electrically connected with the fourth voltage transient suppression diode and the third voltage transient suppression diode respectively, the fourth voltage transient suppression diode and the third voltage transient suppression diode are used for the protection of the communication line, and the third voltage transient suppression diode and the fourth voltage transient suppression diode are connected in parallel between the USB bus data positive, data negative and power supply ground pole respectively, the third pin of the lower isolation control chip is electrically connected with the twentieth capacitor, the second pin of the lower isolation control chip is electrically connected with the eighteenth capacitor and the nineteenth capacitor, and the eighteenth capacitor, the nineteenth capacitor and the twentieth capacitor are all power decoupling capacitors, and the eleventh pin of the lower isolation control chip is electrically connected with the anode of the first light emitting diode through the ninth resistor.
5. The fully isolated touch screen USB interface circuit of claim 4, wherein, Specifically includes: The first optoelectronic coupling unit and the second optoelectronic coupling unit are arranged between the upper isolation control module and the lower isolation control module, the first optoelectronic coupling unit includes a sixth isolation chip and a fifth isolation chip, the second pin and the third pin of the fifth isolation chip are electrically connected with the thirteenth capacitor, and the third pin of the fifth isolation chip is connected in series with the fifth resistor, the fifth pin and the sixth pin of the fifth isolation chip are electrically connected with the fourteenth capacitor and the sixth resistor respectively, the second pin and the third pin of the sixth isolation chip are electrically connected with the thirteenth capacitor, and the third pin of the sixth isolation chip is connected in series with the seventh resistor, and the fifth pin and the sixth pin of the sixth isolation chip are electrically connected with the sixteenth capacitor and the eighth resistor respectively.
6. The fully isolated touch screen USB interface circuit of claim 5, wherein, Specifically includes: The second optoelectronic coupling unit includes a third isolation chip and a second isolation chip, the second pin and the third pin of the second isolation chip are electrically connected with the fourth capacitor, and the third pin of the second isolation chip is connected in series with the first resistor, the fifth pin and the sixth pin of the second isolation chip are electrically connected with the fifth capacitor and the second resistor respectively, the second pin and the third pin of the third isolation chip are electrically connected with the sixth capacitor, and the third pin of the third isolation chip is connected in series with the third resistor, and the fifth pin and the sixth pin of the third isolation chip are electrically connected with the seventh capacitor and the fourth resistor respectively.
7. The fully isolated touch screen USB interface circuit of claim 6, wherein, Specifically includes: The first optoelectronic coupling unit and the second optoelectronic coupling unit optimize the symmetry between the rising edge and the falling edge of the optocoupler output signal by adjusting the fifth resistor, the thirteenth capacitor, the seventh resistor, the fifteenth capacitor, the first resistor, the fourth capacitor, the third resistor and the sixth capacitor, the fifth capacitor, the seventh capacitor, the fourteenth capacitor and the sixteenth capacitor are all decoupling capacitors, and the second resistor, the fourth resistor, the sixth resistor and the eighth resistor are all optocoupler output end pull-up resistors.
8. The fully isolated touch screen USB interface circuit of claim 7, wherein, Specifically includes: The fourth pin of the first connector in the upper isolation control module is connected to an isolation power module through a π type filter circuit, the isolation power module comprises an isolation power chip, the first pin of the isolation power chip is electrically connected with the fourth pin of the first connector in the upper isolation control module, the π type filter circuit is composed of an eighth capacitor, a ninth capacitor, a tenth capacitor and a first inductor, the second pin of the isolation power chip is electrically connected to the power supply ground pole of the computer module, the fifth pin of the isolation power chip is electrically connected to the power supply ground pole of the touch control module, the second pin and the fifth pin of the isolation power chip are electrically connected with a seventeenth capacitor, the seventh pin of the isolation power chip outputs an isolated power supply, and the first pin of the isolation power chip is electrically connected with an eleventh capacitor and a twelfth capacitor.