阅读说明：本技术 一种自动防护屏蔽门 (automatic protective shielding door ) 是由 白云帆 于 2019-09-29 设计创作，主要内容包括：本发明的一种自动防护屏蔽门,行程限位开关采用无触点行程开关进行替换,并由高频振荡电路产生高频振荡信号,并经压控微调后输出稳定的高频振荡信号,之后经预加重电路对高频振荡信号的高频分量进行补偿提升后加到无触点行程开关的探头上,感应出随屏蔽门移动的高频交流电压,经传输线传输过来的高频交流电压经去加重电路还原、检波电路检波为直流电压并计算出平均值后,进入迟滞比较电路与站台发送开、关命令信息对应的电压进行迟滞比较,输出确定的屏蔽门打开或关闭信息对应的高电平,之后经隔离、缓冲后输出给DCU,达不到要求位置时,直流电压传输到DCU,由DCU输出修正后驱动电机信号,带动屏蔽门打开或关闭到要求位置。(The invention relates to an automatic protective shielding door, wherein a travel limit switch is replaced by a non-contact travel switch, a high-frequency oscillation signal is generated by a high-frequency oscillation circuit, a stable high-frequency oscillation signal is output after voltage control fine adjustment, then a high-frequency component of the high-frequency oscillation signal is compensated and lifted by a pre-emphasis circuit and then is added to a probe of the non-contact travel switch, a high-frequency alternating voltage moving along with the shielding door is induced, the high-frequency alternating voltage transmitted by a transmission line is reduced by a de-emphasis circuit, a detection circuit detects the high-frequency alternating voltage into a direct current voltage and calculates an average value, the direct current voltage enters a hysteresis comparison circuit to carry out hysteresis comparison with the voltage corresponding to platform sending opening and closing command information, a high level corresponding to determined opening or closing information of the shielding door is output to a DCU after isolation and buffering, and when the required position is not reached, the direct current voltage is transmitted to, and outputting the corrected driving motor signal by the DCU to drive the shielding door to be opened or closed to a required position.)

1. an automatic protection shield door comprises a platform, a travel limit switch, a DCU (digital control unit) and a motor, wherein the platform sends information to the DCU, the DCU drives the motor to complete the opening or closing task of the shield door, the travel limit switch is triggered when the shield door is opened or closed to a required position, and the triggering information is returned to the DCU to judge the next work;

the high-frequency oscillation circuit generates a high-frequency oscillation signal through an oscillation circuit taking a triode Q1 as a core, the high-frequency oscillation signal is subjected to voltage-controlled fine adjustment to obtain a stable high-frequency oscillation signal, then the high-frequency oscillation signal is compensated through a pre-emphasis circuit consisting of a capacitor C9, a resistor R4, a resistor R7 and an inductor L3 and then is added onto a probe of the contactless travel switch, high-frequency alternating-current voltage moving along with a shielding door is induced on the probe, the high-frequency alternating-current voltage is restored through a de-emphasis circuit consisting of a capacitor C10, a resistor R7, a resistor R9, a resistor R20 and an inductor L4 and then is detected into direct-current voltage through a detection circuit taking a transformer T1 as the core, the direct-current voltage is compared and judged through a hysteresis comparison circuit and then determined opening or closing information of the shielding door is output, one path of the shielding door is isolated and buffered through an isolation circuit and then outputs the opening or closing information of the shielding door, and outputting the corrected driving motor signal by the DCU to drive the shielding door to be opened or closed to a required position.

2. The automatic protective shielded door as claimed in claim 1, wherein the de-emphasis circuit comprises an inductor L4, a resistor R7 and a resistor R8, the left end of the inductor L4, one end of the resistor R7 and one end of the resistor R8 are all connected with probe sensing information received via transmission lines, the other end of the resistor R7 is respectively connected with one end of the resistor R20 and one end of the resistor R9, the other end of the resistor R20 is connected with one end of a grounding capacitor C10, the right end of the inductor L4 is respectively connected with the other end of the resistor R8 and the other end of the resistor R9, and the right end of the inductor L4 is used for de-emphasis circuit output signals;

The detection circuit comprises a transformer T1, one end of a pin 6 of the transformer T1 and one end of a capacitor C1 are connected with the other end of a resistor R9, the other end of a pin 5 of the transformer T1 and the other end of a capacitor C1 are connected with the other end of a resistor R9, a pin 3 of the transformer T1 is respectively connected with one end of a capacitor C12 and the anode of a diode D3, the cathode of a diode D3 is respectively connected with one end of a capacitor C13 and one end of a resistor R11, a pin 2 of the transformer T1 is connected with one end of an inductor L5, a pin 1 of the transformer T1 is respectively connected with the other end of a capacitor C1 and the cathode of a diode D1, the anode of a diode D1 is respectively connected with one end of a capacitor C1 and one end of a resistor R1, the other end of the inductor L1, the other end of the capacitor AR1 and the other end of the capacitor C1 are both connected with the ground, the other end of the resistor R, One end of a resistor R14, the other end of the resistor R14 is connected with the other end of a resistor R11, one end of a resistor R13 and the non-inverting input end of an operational amplifier AR1 respectively, the inverting input end of the operational amplifier AR1 is connected with the ground, the output end of the operational amplifier AR1 is connected with the other end of the resistor R13 and one end of an inductor L1 respectively, and the other end of the inductor L1 is used as an output signal of the detection circuit;

the hysteresis comparison circuit comprises an operational amplifier AR3, wherein the non-inverting input end of the operational amplifier AR3 and the emitter of a triode Q1 are connected with the other end of an inductor L1, the inverting input end of the operational amplifier AR3 is respectively connected with the emitter of a triode Q2, one end of a resistor R15 and one end of a grounding resistor R16, the collector of the triode Q2 and the other end of the resistor R15 are connected with shielding door opening or closing information sent by a platform, the output end of the operational amplifier AR3 is respectively connected with the base of a triode Q2 and the base of a triode Q4, and the collector of an IO 4 is connected with an IO port of a DCU;

the isolation circuit comprises a photoelectric coupler U1, a pin 1 of a photoelectric coupler U1 is connected with the output end of an operational amplifier AR3, a pin 2 of the photoelectric coupler U1 is connected with the ground, a pin 3 of the photoelectric coupler U1 is connected with a signal ground, a pin 4 of a photoelectric coupler U1 is respectively connected with one end of a resistor R17 and the base of a triode Q3, a collector of the triode Q3 is respectively connected with one end of a resistor R18 and an IO port of a DCU, the other end of the resistor R17 and the other end of a resistor R18 are connected with a power supply +5V, and an emitter of the triode Q3 is connected with the signal ground through a resistor R19.

3. The automatic shielding gate of claim 1, wherein the high frequency oscillating circuit comprises a transistor Q1, a base of the transistor Q1 is connected to one end of a ground resistor R2 and one end of a resistor R1, a collector of the transistor Q1 is connected to one end of an inductor L1, one end of a capacitor C1, one end of a capacitor C3 and one end of a capacitor C6, the other end of the resistor R1, the other end of the inductor L1 and the other end of the capacitor C1 are connected to +5V, the other end of the capacitor C3 is connected to an anode of a varactor DC2 and one end of a capacitor C4, a cathode of the varactor DC2 is connected to one end of a capacitor C2, the other end of the capacitor C2 is connected to an emitter of a transistor Q1 and one end of an inductor L2, the other end of the inductor L2 is connected to one end of a ground resistor R3, the other end of a capacitor C3 and one end of a ground capacitor C3, and the other end of a capacitor C3 are connected to one, One end of a grounding capacitor C8, the other end of the capacitor C7 is respectively connected with the anode of the diode D1 and the cathode of the diode D2, the cathode of the diode D1 is respectively connected with the cathode of the varactor DC2, one end of a grounding capacitor C6 and the anode of the diode D2 are connected with the ground;

The pre-emphasis circuit comprises a resistor R4, a resistor R5 and a capacitor C9, one end of the resistor R4, one end of the resistor R5 and one end of the capacitor C9 are all connected with one end of a capacitor C6, the other end of the resistor R5 is respectively connected with one end of the resistor R6 and one end of a resistor R7, the other end of the resistor R7 is connected with one end of an inductor L3, the other end of the inductor L3 is connected with the ground, the other end of the resistor R6 is respectively connected with the other end of the resistor R4, the other end of the capacitor C9 and one end of a probe of a non-contact travel switch, and the other end of the probe.

4. An automatic protective screen door as claimed in claims 1 to 3, wherein said contactless travel switch is a proximity switch of the eddy current type.

Technical Field

The invention relates to the technical field of shield door safety protection, in particular to an automatic protection shield door.

Background

The shielding door is an isolation protection device for a public area and a rail running area of a platform of an urban rail transit station, and mainly plays a role in reducing the influence of train running noise and piston wind on waiting passengers at the platform of the station and preventing personnel from falling off the rail and causing accidents.

However, the travel limit switch is mechanically operated, the mechanical service life is about 10 ten thousand times, and as the door opening and closing times are increased, the contact can cause mechanical abrasion and the elastic performance of the spring is reduced, so that the contact of the travel limit switch cannot act and reset, and the touch information cannot be accurately returned to the DCU when the shielding door is opened or closed to a required position.

disclosure of Invention

In view of the above situation, in order to overcome the defects of the prior art, the present invention aims to provide an automatic protection shield door, which has the characteristics of ingenious conception and humanized design, and effectively solves the problems that the travel limit switch is not well touched and the touch information can not be accurately returned to the DCU when the shield door is opened or closed to the required position.

The technical scheme includes that the device comprises a platform, a travel limit switch, a DCU and a motor, wherein the platform sends information to the DCU, the DCU drives the motor to complete the opening or closing task of a shielding door, the travel limit switch is triggered when the shielding door is opened or closed to a required position, and the triggering information is returned to the DCU to judge the next work;

The high-frequency oscillation circuit generates a high-frequency oscillation signal through an oscillation circuit taking a triode Q1 as a core, the high-frequency oscillation signal is subjected to voltage-controlled fine adjustment to obtain a stable high-frequency oscillation signal, then the high-frequency oscillation signal is compensated through a pre-emphasis circuit consisting of a capacitor C9, a resistor R4, a resistor R7 and an inductor L3 and then is added onto a probe of the contactless travel switch, high-frequency alternating-current voltage moving along with a shielding door is induced on the probe, the high-frequency alternating-current voltage is restored through a de-emphasis circuit consisting of a capacitor C10, a resistor R7, a resistor R9, a resistor R20 and an inductor L4 and then is detected into direct-current voltage through a detection circuit taking a transformer T1 as the core, the direct-current voltage is compared and judged through a hysteresis comparison circuit and then determined opening or closing information of the shielding door is output, one path of the shielding door is isolated and buffered through an isolation circuit and then outputs the opening or closing information of the shielding door, and outputting the corrected driving motor signal by the DCU to drive the shielding door to be opened or closed to a required position.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the following advantages: the method comprises the following steps that 1, a non-contact travel switch is adopted to replace a travel limit switch, a high-frequency oscillation signal is generated through an oscillation circuit, is converted into direct-current voltage after being detected, is added to the negative electrode of a variable capacitance diode DC2, is further finely adjusted, outputs a high-frequency oscillation signal with stable frequency, compensates and promotes the high-frequency component of the high-frequency oscillation signal through a pre-emphasis circuit, and then is added to a probe of the non-contact travel switch, so that the signal-to-noise ratio in the signal transmission process is improved, and the detection precision is improved; 2, inducing a high-frequency alternating-current voltage moving along with the shield door on the probe, performing de-emphasis reduction and detection to obtain a direct-current voltage, calculating an average value, adding the direct-current voltage to a non-inverting input end of an operational amplifier AR3, performing hysteresis comparison with a voltage corresponding to platform sending on-off command information provided by an inverting input end of the operational amplifier AR3, outputting a high level corresponding to determined shield door opening or closing information when the direct-current voltage reaches a voltage allowable range corresponding to a required position, then outputting the high level to a DCU after isolation and buffering, outputting a low level when the required position is not reached, triggering a triode Q4 to be conducted, transmitting the direct-current voltage to the DCU, outputting a modified driving motor signal by the DCU, and driving the shield door to be opened or closed to the required position.

Drawings

The left part of fig. 1 is a schematic diagram of a high-frequency oscillation circuit of the present invention, and the right part is a schematic diagram of a pre-emphasis circuit of the present invention.

Fig. 2 is a schematic diagram of the de-emphasis circuit, the detector circuit, the hysteresis comparator circuit and the isolation circuit of the present invention from left to right.

Detailed Description

the foregoing and other aspects, features and advantages of the invention will be apparent from the following more particular description of embodiments of the invention, as illustrated in the accompanying drawings in which reference is made to figures 1-2. The structural contents mentioned in the following embodiments are all referred to the attached drawings of the specification.

Exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

An automatic protection shield door comprises a platform, a travel limit switch, a DCU and a motor, wherein the platform sends information to the DCU, the DCU drives the motor to complete the opening or closing task of the shield door, the travel limit switch is triggered when the shield door is opened or closed to a required position, the triggering information is returned to the DCU to judge the next work, the travel limit switch is replaced by a non-contact travel switch and is added to a probe of the non-contact travel switch after being processed by a high-frequency oscillation circuit and a pre-emphasis circuit, and the information after induction is returned to the DCU after being processed by a de-emphasis circuit, a detection circuit, a hysteresis comparison circuit and an isolation circuit;

The high-frequency oscillation circuit generates a high-frequency oscillation signal through an oscillation circuit consisting of a triode Q1, a capacitor C2-a capacitor C5, a varactor DC2, an inductor L1, an inductor L2 and a resistor R1-a resistor R3, the high-frequency oscillation signal is converted into direct-current voltage after being detected by the diode D1 and a diode D2 and is added to the negative electrode of the varactor DC2, the frequency of the high-frequency oscillation signal generated by the oscillation circuit is finely adjusted, the high-frequency oscillation signal with stable frequency is output, then the high-frequency component of the high-frequency oscillation signal is compensated and boosted through a pre-emphasis circuit consisting of the capacitor C9, the resistor R4-the resistor R7 and the inductor L3 and is added to a probe of a contactless travel switch so as to increase the signal-to-noise ratio in the signal transmission process, an alternating magnetic field is generated on the probe to induce high-frequency alternating-current voltage moving along with a shielding gate, the de-emphasis circuit induces high-frequency, the high-frequency component of the high-frequency alternating voltage is restored through a de-emphasis circuit consisting of a capacitor C10, a resistor R7, a resistor R9, a resistor R20 and an inductor L4, the signal-to-noise ratio in the signal transmission process is improved, namely, the anti-interference capability in the signal transmission process is improved, the high-frequency alternating voltage enters a detection circuit, the high-frequency alternating voltage after de-resonance and emphasis is obtained through a transformer T1, the high-frequency alternating voltage is bidirectionally detected into direct current voltage through two half-wave diodes D3 and D4, an average value is calculated by an average value circuit taking an operational amplifier AR1 as a core, the average value is finally output to a non-inverting input end of an operational amplifier AR3 of a hysteresis comparison circuit after being smoothly filtered through an inductor L1 and is compared with voltage corresponding to station on-off command information provided by an inverting input end of an operational amplifier AR3, when the direct current voltage reaches a voltage allowable range corresponding to a required position, a high level is output, and, when the direct current voltage is only slightly fluctuated at 0V and +5V, the high level corresponding to the opening or closing information of the determined shielding door is output, when the high level does not reach the required position, the low level is output, the triode Q4 is triggered to be conducted, the direct current voltage is transmitted to the DCU, the DCU outputs a corrected driving motor signal to drive the shielding door to be opened or closed to the required position, and finally, the shielding door is isolated by the isolation circuit photoelectric coupler U1 and further buffered by the triode Q3 to output the high level in the opening or closing state of the shielding door to the DCU, so that the DCU is electrically isolated from the field probe.

in the above technical solution, the de-emphasis circuit receives a high-frequency ac voltage induced on the probe by the transmission line and moving along with the shield door, the de-emphasis circuit composed of the capacitor C10, the resistor R7-the resistor R9, the resistor R20, and the inductor L4 restores the high-frequency component of the high-frequency ac voltage, that is, removes the high-frequency component lifted by pre-emphasis, and the pre-emphasis and de-emphasis make the frequency and amplitude of the high-frequency ac voltage constant, thereby improving the signal-to-noise ratio during signal transmission, that is, improving the anti-interference capability during signal transmission, and further improving the position accuracy when detecting the open or closed state of the shield door, the de-emphasis circuit includes an inductor L4, a resistor R7, and a resistor R8, the left end of the inductor L4, one end of the resistor R7, and one end of the resistor R8 are all connected to probe induction information received by the transmission line, the other end of the resistor R7 is respectively connected to one end of the, the other end of the resistor R20 is connected with one end of a grounding capacitor C10, the right end of the inductor L4 is respectively connected with the other end of the resistor R8 and the other end of the resistor R9, and the right end of the inductor L4 is used as an output signal of the de-emphasis circuit;

The detection circuit detunes the emphasized high-frequency alternating voltage through a transformer T1, the high-frequency alternating voltage is bidirectionally detected into direct current voltage through two half-wave diodes D3 and D4, an average value is calculated through an average value circuit taking an operational amplifier AR1 as a core, the average value is output after being smoothed and filtered through an inductor L1, specifically, positive half cycle is subjected to positive detection through a diode D3 series capacitor C13, the detected high-frequency alternating voltage is added to a non-inverting input end of the operational amplifier AR1 through a resistor R11, negative half cycle is subjected to negative detection through a diode D4 series capacitor C8, the detected high-frequency alternating voltage is added to a non-inverting input end of the operational amplifier AR2 through a resistor R14, the operational amplifier AR1, a resistor R11, a resistor R14 and a resistor R13 form the average value circuit, two input signals are added and then subjected to 1/2 times of operation, the resistor R11 is set to be equal to a resistor R14 to be equal to 2 times R13, the average value comprises, pin 6 of transformer T1 and one end of capacitor C1 are connected to the other end of resistor R9, pin 5 of transformer T1 and the other end of capacitor C1 are connected to ground, pin 3 of transformer T1 is connected to one end of capacitor C12 and the anode of diode D3, the cathode of diode D3 is connected to one end of capacitor C13 and one end of resistor R11, pin 2 of transformer T1 is connected to one end of inductor L5, pin 1 of transformer T1 is connected to the other end of capacitor C12 and the cathode of diode D12, the anode of diode D12 is connected to one end of capacitor C12 and one end of resistor R12, the other end of inductor L12, the other end of capacitor C12 and the other end of capacitor C12 are connected to ground, the other end of resistor R12 is connected to the inverting input terminal of operational amplifier AR 12, the non-inverting input terminal of operational amplifier 12 is connected to the output terminal of operational amplifier AR 12 and one end of resistor R12, the other end of the resistor R14 is respectively connected with the other end of the resistor R11, one end of the resistor R13 and the non-inverting input end of the operational amplifier AR1, the inverting input end of the operational amplifier AR1 is connected with the ground, the output end of the operational amplifier AR1 is respectively connected with the other end of the resistor R13 and one end of the inductor L1, and the other end of the inductor L1 is used for outputting a signal by a detection circuit;

The hysteresis comparator circuit adds the detected direct current voltage to the non-inverting input terminal of the operational amplifier AR3, compares the detected direct current voltage with the voltage corresponding to the platform transmission on/off command information provided by the inverting input terminal of the operational amplifier AR3 (specifically, a non-contact travel switch for detecting the opening state or closing state of the shielding door is provided, and the platform transmission on/off command information accessed by the voltage dividing circuit consisting of the resistor R15 and the resistor R16 is defined as on/off command information of 0V and + 5V), outputs a high level when the direct current voltage reaches the voltage allowable range corresponding to the required position, and feeds back the output information to the inverting input terminal of the operational amplifier AR3 through the triode Q2, so that when the direct current voltage fluctuates slightly at 0V and +5V, the high level corresponding to the determined opening or closing information of the shielding door is output, and outputs a low level when the direct current voltage does not reach the required position, the trigger triode Q4 is switched on, direct-current voltage is transmitted to a DCU, the DCU outputs a corrected driving motor signal to drive a shielding door to be opened or closed to a required position (the DCU outputs the corrected driving motor signal according to the direct-current voltage, the operation state of the motor is further corrected, the DCU is the prior art and is not detailed), the device comprises an operational amplifier AR3, the non-inverting input end of the operational amplifier AR3 and the emitter of a triode Q1 are connected with the other end of an inductor L1, the inverting input end of the operational amplifier AR3 is respectively connected with the emitter of a triode Q2, one end of a resistor R15 and one end of a grounding resistor R16, the collector of a triode Q2 and the other end of a resistor R15 are connected with shielding door opening or closing information sent by a platform, the output end of the operational amplifier AR3 is respectively connected with the base of a triode Q2 and the base of a triode Q4;

The isolation circuit receives a high level corresponding to the in-place state of the shielding door, outputs the in-place high level of the opening or closing state of the shielding door to a DCU after being isolated by a photoelectric coupler U1 and further buffered by a triode Q3, and enables the DCU to be electrically isolated from an on-site probe.

In the above technical solution, the high frequency oscillation circuit generates a high frequency oscillation signal through an oscillation circuit composed of a triode Q1, a capacitor C2-a capacitor C5, a varactor diode DC2, an inductor L1, an inductor L2 and a resistor R1-a resistor R3, wherein the resistor R1 and the resistor R2 provide a base bias voltage for the triode Q1, the inductor L1 and the capacitor C1 provide a collector bias voltage, the high frequency oscillation signal is detected by a diode D1 and a diode D2 and then converted into a direct current voltage, the direct current voltage is applied to a negative electrode of the varactor diode DC2, the frequency of the high frequency oscillation signal generated by the oscillation circuit is finely adjusted, and the high frequency oscillation signal with stable frequency is output and comprises a triode Q1, the base of the triode Q1 is respectively connected with one end of a ground resistor R2 and one end of a resistor R1, the collector of the triode Q1 is respectively connected with one end of an inductor L1, one end of a capacitor C1, one end, the other end of the resistor R1, the other end of the inductor L1 and the other end of the capacitor C1 are all connected with +5V of a power supply, the other end of the capacitor C3 is respectively connected with the anode of the varactor DC2 and one end of the capacitor C4, the cathode of the varactor DC2 is connected with one end of the capacitor C2, the other end of the capacitor C2 is respectively connected with the emitter of the triode Q1 and one end of the inductor L2, the other end of the inductor L2 is respectively connected with one end of a grounding resistor R3, the other end of the capacitor C4 and one end of a grounding capacitor C5, the other end of the capacitor C6 is respectively connected with one end of the capacitor C7 and one end of a grounding capacitor C8, the other end of the capacitor C7 is respectively connected with the anode of the diode D1 and the cathode of the diode D2, the cathode of the diode D1 is respectively connected with the cathode of the varactor DC 2;

the pre-emphasis circuit compensates and lifts the high-frequency component of the received high-frequency oscillation signal through a pre-emphasis circuit consisting of a capacitor C9, a resistor R4-a resistor R7 and an inductor L3 and then adds the high-frequency component to a probe of the contactless travel switch, the high-frequency alternating-current voltage sensor comprises a resistor R4, a resistor R5 and a capacitor C9, wherein one end of the resistor R4, one end of the resistor R5 and one end of the capacitor C9 are connected with one end of a capacitor C6, the other end of the resistor R5 is connected with one end of a resistor R6 and one end of a resistor R7 respectively, the other end of the resistor R7 is connected with one end of an inductor L3, the other end of the inductor L3 is connected with the ground, the other end of the resistor R6 is connected with the other end of the resistor R4, the other end of the capacitor C9 and one end of a probe of a non-contact travel switch respectively, and the other end of the probe of the non-contact travel switch is connected with the ground.

When the invention is used specifically, the travel limit switch is replaced by a non-contact travel switch, the travel limit switch is processed by a high-frequency oscillation circuit and a pre-emphasis circuit and then is added to a probe of the non-contact travel switch, and information after induction is processed by a de-emphasis circuit, a detection circuit, a hysteresis comparison circuit and an isolation circuit and then is returned to a DCU;

The high-frequency oscillation circuit generates a high-frequency oscillation signal through an oscillation circuit, the high-frequency oscillation signal is converted into direct-current voltage after being detected by a diode D1 and a diode D2 and then is added to the negative electrode of a variable capacitance diode DC2, the frequency of the high-frequency oscillation signal generated by the oscillation circuit is finely adjusted, the high-frequency oscillation signal with stable frequency is output, then the high-frequency component of the high-frequency oscillation signal is compensated and improved through a pre-emphasis circuit consisting of a capacitor C9, a resistor R4, a resistor R7 and an inductor L3 and then is added to a probe of a contactless travel switch so as to improve the signal-to-noise ratio in the signal transmission process, an alternating magnetic field is generated on the probe to induce high-frequency alternating-current voltage moving along with a shielded gate, the de-emphasis circuit receives the high-frequency alternating-current voltage induced on the probe along with the shielded gate through a transmission line, the high-frequency component of the, the frequency and the amplitude of the high-frequency alternating voltage are unchanged through pre-emphasis and de-emphasis, the signal-to-noise ratio in the signal transmission process is improved, namely, the anti-interference capability in the signal transmission is improved, the position precision in the process of detecting the opening or closing state of the shielding door is improved, then the high-frequency alternating voltage enters a detection circuit, the high-frequency alternating voltage after resonance and emphasis is removed through a transformer T1, the high-frequency alternating voltage is bidirectionally detected into direct current voltage through two half-wave diodes D3 and D4, an average value is calculated by an average value circuit with an operational amplifier AR1 as a core, the average value is finally output to a non-inverting input end of a hysteresis comparison circuit operational amplifier AR3 after being smoothly filtered by an inductor L1, the voltage is compared with the voltage corresponding to the platform sending opening and closing command information provided by an inverting input end of the operational amplifier AR3, and when the direct current voltage reaches, and the output information is fed back to the inverting input end of the operational amplifier AR3 through the triode Q2, when the direct-current voltage fluctuates slightly at 0V and +5V, the high level corresponding to the opening or closing information of the determined shielding door is output, when the required position cannot be reached, the low level is output, the triode Q4 is triggered to be conducted, the direct-current voltage is transmitted to the DCU, the DCU outputs a corrected driving motor signal to drive the shielding door to be opened or closed to the required position, and finally the shielding door is isolated through the isolation circuit photocoupler U1, the triode Q3 further buffers and outputs the high level in which the opening or closing state of the shielding door is in place to the DCU, so that the DCU is electrically isolated from the field probe.