CN110685531A

CN110685531A - Safety light curtain

Info

Publication number: CN110685531A
Application number: CN201911008021.7A
Authority: CN
Inventors: 邓志才; 陈坤速
Original assignee: SHANGHAI SUODILONG AUTOMATION Co Ltd
Current assignee: Shanghai sodilon Automation Co.,Ltd.
Priority date: 2019-10-22
Filing date: 2019-10-22
Publication date: 2020-01-14
Anticipated expiration: 2039-10-22
Also published as: CN110685531B

Abstract

The invention provides a safety light curtain which comprises an infrared transmitter and an infrared receiver, wherein the infrared transmitter comprises a first power supply module and a transmitting module, the infrared receiver comprises a second power supply module, a signal receiving and processing module and a dual-channel control module which are sequentially connected, each control module comprises a control MCU, an output control circuit and an output detection circuit, the two control MCUs are connected with the signal receiving and processing module, the two control MCUs are respectively connected with the output control circuit of a corresponding channel to output control signals to the output control circuit, and each output detection circuit is respectively connected with the output control circuit and the control MCU of the corresponding channel, so that each channel can detect faults of the output control circuit through the output detection circuit and feed back the faults to the corresponding control MCU. The invention can realize effective control and diagnosis functions; the output is detected to be double-path self-checking and mutual checking, the failure of a single element cannot cause the loss of the safety function, and the safety is ensured.

Description

Safety light curtain

Technical Field

The invention belongs to the technical field of safety light curtains, and particularly relates to a safety light curtain.

Background

The safety light curtain is composed of an infrared transmitter and an infrared receiver, the infrared transmitter and the infrared receiver are respectively installed on two sides of a shielding door or an elevator door, an equipment door and the like, the infrared transmitter can transmit infrared detection light beams, and the infrared receiver receives signals. When an object blocks the shielding door, the infrared receiver can not detect the light beam signal emitted by the emitter, and the light beam signal can be fed back to the control unit, and the control unit outputs a control signal to act, such as enabling the shielding door which is being closed to be opened reversely.

If the output control unit of the light curtain breaks down, the malfunction of the shielding door can not be reversed and opened in time, which causes danger and the like. The existing light curtain product cannot realize effective real-time self-checking and output control, and needs to be improved to improve safety and reliability.

Disclosure of Invention

The invention aims to solve the technical problems and provide a safety light curtain with a dual-channel control function.

In order to achieve the purpose, the invention adopts the following technical scheme:

the safety light curtain is characterized in that the infrared receiver comprises a second power module, a signal receiving and processing module and a double-channel control module which are sequentially connected, each control module comprises a control MCU, an output control circuit and an output detection circuit, the two control MCUs are connected to the signal receiving and processing module, the two control MCUs are respectively connected to the output control circuit of the corresponding channel to output control signals to the output control circuit, and each output detection circuit is respectively connected to the output control circuit and the control MCU of the corresponding channel, so that each channel can detect faults of the output control circuit through the output detection circuit and feed back the faults to the corresponding control MCU.

In the above safety light curtain, the output control circuit includes a first MOS transistor and a driving circuit for driving the first MOS transistor, and the control signal of the control MCU is output to the driving circuit.

In foretell safety light curtain, the voltage monitoring end of two way control MCU connects respectively in comparison circuit in order to carry out undervoltage and overvoltage monitoring respectively to two way control MCU, just comparison circuit links to each other through AND gate to two way control MCU's voltage monitoring output, AND gate's output is connected to two drive circuit of binary channels control module respectively in order to realize the safe output to two way output control circuit through arbitrary control MCU's undervoltage overvoltage signal.

In the above-mentioned safety light curtain, the two control MCU connections are respectively connected with the watchdog circuit of each channel, and the two watchdog circuits are respectively connected with the corresponding channel driving circuit to realize the safety output to the corresponding output control circuit through the watchdog circuit.

In the above safety light curtain, the two control MCUs are respectively connected with the unloading control modules of their respective channels, each unloading control module includes a second MOS transistor, and the second MOS transistors are bidirectionally connected to the control MCUs of the corresponding channels so that the corresponding control MCUs perform unloading control output self-checking.

In the above-mentioned safety light curtain, through parallel port communication connection in order to carry out information exchange and double-circuit mutual detection between two control MCU, just parallel port department is connected with display module.

In the above safety light curtain, the emission module includes an emission MCU and an emission signal processing circuit connected to the emission MCU, the emission signal processing circuit is connected to a signal transmission circuit, and a clock end of the signal transmission circuit is connected to the emission MCU to control the start of emission through the emission MCU.

In the above safety light curtain, the signal transmission circuit includes a plurality of emission chips, each emission chip is connected with a plurality of light emitting diodes to transmit the emission signal in the form of an infrared signal through the light emitting diode;

and the transmitting MCU outputs preset codes for each light emitting diode through the transmitting signal processing circuit so that the transmitting signal processing circuit transmits infrared signals in a light coding mode.

In the above safety light curtain, the clock end of each emission chip is connected to the emission MCU, the emission chips are connected in cascade via Do and Di, and the Di end of the first emission chip and the Do end of the last emission chip are connected to the emission MCU via the period scanning module to perform control and monitoring of the cycle period via the emission MCU.

In foretell safety light curtain, signal reception and processing module includes signal reception circuit and received signal processing circuit, signal reception circuit includes a plurality of receiving chips that are used for receiving infrared signal, receiving chip's output all connects in received signal processing circuit, received signal processing circuit is including consecutive trigger signal processing circuit and serial signal processing singlechip, trigger signal processing circuit and serial signal processing singlechip all connect in two ways MCU in order to carry out trigger signal and carry out parallel output to two way control MCU output.

In the safety light curtain, the clock ends of a plurality of receiving chips are connected with two paths of control MCUs, one path of the control MCU provides a clock signal, and the other path of the control MCU monitors;

the plurality of receiving chips are connected in cascade in a Do and Di connection mode, and the Di end of the first receiving chip is connected to at least one of the two paths of control MCUs so as to control the start of a receiving period through the control MCU.

The invention has the advantages that: the effective control and diagnosis functions can be realized by using a double-channel real-time diagnosis mode; the detected output is double-path self-checking and mutual-checking, the failure of a single element cannot cause the loss of the safety function, and the safety system can detect the failure when or before the next operation is carried out; the emitted light is designed into a coded signal, the capacity of resisting external light interference and the capacity of resisting EMC interference are improved, the system precision is also improved, and the system has stronger electromagnetic compatibility capability by matching with other conventional EMC measures.

Drawings

FIG. 1 is a block diagram of the circuit structure of the safety light curtain of the present invention;

FIG. 2 is a schematic block diagram of the emission of the safety light curtain of the present invention;

FIG. 3 is a timing diagram of the emission of the safety light curtain of the present invention;

FIG. 4 is a schematic block diagram of the reception of the safety light curtain of the present invention;

FIG. 5 is a timing diagram of the reception of the safety light curtain of the present invention;

FIG. 6 is a schematic diagram of the output control of the safety light curtain of the present invention;

fig. 7 is a flow chart of the safety light curtain program control of the present invention.

Reference numerals: an infrared emitter 1; a first power supply module 11; a transmit MCU 12; a transmission signal processing circuit 13; a signal transmission circuit 14; a periodic scanning module 15; an infrared receiver 2; a second power supply module 21; a control MCU 22; an output control circuit 23; a signal receiving circuit 24; the received signal processing circuit 25; an output detection circuit 26; a display module 27.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1, this embodiment discloses a safety light curtain, including infrared emitter 1 and infrared receiver 2, infrared emitter 1 is a single channel system, mainly comprises first power module 11 and a transmitting module for transmitting infrared signals, wherein the transmitting module includes transmitting MCU12, transmitting signal processing circuit 13, periodic scanning module 15 and signal transmitting circuit 14, transmitting signal processing circuit 13 is connected to signal transmitting circuit 14 to process the transmitting signal output by transmitting MCU12 and then send to signal transmitting circuit 14, the clock end of signal transmitting circuit 14 is connected to transmitting MCU12 to control the start of transmission through transmitting MCU 12. The infrared receiver 2 is a dual-channel system, and mainly comprises a second power module 21, a display module 27, a signal receiving and processing module and a dual-channel control module, each control module comprises a control MCU22, a control output circuit 23 and an output detection circuit 26, wherein the signal receiving and processing module comprises a signal receiving circuit 24 and a received signal processing circuit 25.

Specifically, as shown in fig. 2 and 3, the signal transmission circuit 14 includes a plurality of emission chips, each of which is connected with a plurality of light emitting diodes to transmit the emission signal in the form of an infrared signal through the light emitting diode; specifically, the transmission signal processing circuit 13 is connected to all the transmission chips to process the transmission signal output by the transmission MCU12 and then send the processed signal to the transmission chips.

Preferably, the transmitting MCU12 outputs a preset code of a certain length for each light emitting diode through the transmitting signal processing circuit 13 according to the transmitting signal to be transmitted, so that the transmitting signal processing circuit 13 transmits the infrared signal in the form of optical code.

The clock end of each emission chip is connected to the emission MCU12, the emission chips are connected in cascade in a manner that Do and Di are connected, and the Di end of the first emission chip and the Do end of the last emission chip are connected to the emission MCU12 through the period scanning module 15 to perform control and monitoring of the cycle period through the emission MCU 12. The periodic scanning module 15 may be an internal module of the transmitting MCU12 or an external module independent of the transmitting MCU12, etc.

Specifically, the emission principle of the present embodiment is described here by taking three emission chips, i.e., IC driver1, IC driver2, and IC driver13, as an example:

fig. 2 and 3 are a schematic block diagram and a timing diagram respectively illustrated by three emitting chips, i.e., an IC driver1, an IC driver2, and an IC driver 13. Each emitting chip drives 8 paths of LEDs to work, the emitting MCU12 outputs codes with a certain length for each LED according to a clock, the codes are processed by the emitting signal processing circuit 13 and then sent to the input pins MOD, Di1 and CLK low level of the corresponding emitting chip to control the beginning of emission, CLK high level of the emitting chip completes the switching of emitting lamps, the emitting chips are cascaded in a mode of connecting Do1 and Di2, and the Do3 and Di1 of the last LED emitting chip are connected 15 through the periodic scanning module, so that the emitting circulation controlled by the clock is realized.

The main diagnostic measures of the infrared emitter 1 are listed below: first, the Di1 of the emitting chip IC driver1 changes from 1 to 0 to indicate the beginning of one emitting period, the Do3 of the IC driver3 changes from 1 to 0 to indicate the end of one emitting period, and the emitting MCU12 monitors the timing monitoring emitting periods of Di1 and Do3 and the state of the infrared emitter 1 through the period scanning module 15.

Preferably, the first power module 11 can add an over-voltage and under-voltage detection circuit to ensure that a stable power is provided for the infrared emitter 1, thereby improving the reliability of the safety function. In addition, in order to prevent the resolution from being reduced due to the short circuit between the LEDs, a current detection circuit may be further designed to detect the emission current.

Further, as shown in fig. 1, 4 and 5, the two control MCUs 22 of the infrared receiver 2 are connected to the received signal processing circuit 25, the two control MCUs 22 are respectively connected to the output control circuits 23 of the corresponding channels to output control signals to the output control circuits 23, and each output detection circuit 26 is respectively connected to the output control circuit 23 and the control MCU22 of the corresponding channel, so that each channel performs fault detection on the output control circuit 23 through the output detection circuit 26 and feeds back the fault detection to the corresponding control MCU22 for controlling output self-detection. When in use, the two-way output control circuit 23 output may be connected in parallel to a load circuit to perform safety actions via output signals OSSD1/OSSD2 of any of the channels.

Further, two control MCUs 22 are in communication connection through a parallel port, and the parallel port is connected with a display module 27, so that two control MCUs 22 share the parallel port to exchange information and monitor each other, thereby realizing two-way mutual detection.

As shown in fig. 6, the output control circuit 23 includes first MOS transistors Q17 and Q11 and a driving circuit EN for driving the first MOS transistors, and the control signals OSSD 1C 1 and OSSD 2C 1 of the control MCU22 are output to the respective driving circuits EN. Specifically, the first MOS transistor is a P-channel MOS transistor. The driving circuit EN may be a driving chip for driving the first MOS transistors Q17 and Q11 or any other feasible pure circuit structure, and the driving circuit EN outputs a trigger signal, such as a high level or a low level, to the first MOS transistors Q17 and Q11 according to the received control signal. Preferably, the voltage monitoring ends of the two-way control MCU22 are respectively connected to the comparator circuit compare to respectively monitor the two-way control MCU22 for undervoltage and overvoltage, the voltage monitoring output ends of the comparator circuit compare to the two-way control MCU22 are connected to the and circuit, and the output ends of the and circuit are respectively connected to the two driving circuits EN of the two-way control module to realize safe output of the two-way output control circuit 23 through the overvoltage and undervoltage judgment signal of the arbitrary control MCU 22. The comparison circuit provides a reference voltage of 5V, and the reference voltage is overvoltage when the reference voltage is higher than a first preset value of 5V and is low when the reference voltage is lower than a second preset value of 5V, wherein the first preset value and the second preset value are both determined by a person skilled in the art according to the working voltage of the MCU, for example, the working allowable voltage of the MCU is 4.2-5.5, and then the first preset value and the second preset value are respectively 0.5 and 0.8.

Further, the two control MCUs 22 are respectively connected to a watchdog circuit WDT of each channel, and the two watchdog circuits WDT are respectively connected to the corresponding channel driving circuit EN to realize safe output to the corresponding output control circuit 23 through the watchdog circuit WDT. The working condition of the MCU22 is correspondingly controlled by monitoring the watchdog circuit WDT, and the watchdog circuit WDT outputs direct control output, so that the MCU22 can be safely output when working error occurs.

Further, the two control MCUs 22 are respectively connected to unloading control modules of their respective channels, output short circuit is intentionally caused, whether current flows through the output end of the unloading control module is detected to determine whether the circuit is normal, each unloading control module includes a second MOS transistor Q20, Q12, and the second MOS transistors Q20, Q12 are bidirectionally connected to the control MCU22 of the corresponding channel to enable the corresponding control MCU22 to perform unloading control output self-check, for example, the unloading feedback circuit is reversely connected to the MCU22 to feed back to the MCU22 whether the second MOS transistors Q20, Q12 are normal. The second MOS tube is an N-channel MOS tube.

In addition, the second power module 21 is also equipped with an overvoltage and undervoltage detection circuit overload protection, and feeds back the detection result to the control box MCU22 of the corresponding channel, so as to ensure the working voltage of the infrared receiver 2.

Specifically, as shown in fig. 4, the signal receiving circuit 24 includes a plurality of receiving chips IC1 to ICn for receiving infrared signals, and output terminals of the receiving chips are connected to the received signal processing circuit 25. Specifically, the received Signal Processing circuit 25 includes a trigger Signal Processing circuit Signal Processing and a serial Signal Processing single chip microcomputer Signal Processing, which are connected in sequence, and both the trigger Signal Processing circuit and the serial Signal Processing single chip microcomputer are connected to the two-way control MCU22 to output the trigger Signal to the two-way control MCU22 and perform parallel output.

Furthermore, the clock ends of the multiple receiving chips are connected to the two paths of control MCUs 22, one path of the control MCUs 22 provides clock signals, and the other path of the control MCUs 22 monitors; the plurality of receiving chips are connected in cascade in a Do and Di connection mode, and the Di end of the first receiving chip is connected to at least one of the two paths of control MCU22 to control the start of the receiving period through the control MCU 22.

The receiving principle of the present embodiment will be explained based on the foregoing explanation of the transmitting principle of the three transmitting chips:

as shown in fig. 4 and 5, similar to the transmission, the receiving chips IC 1-ICn are cascade-connected to sequentially and circularly receive the photocurrent signal of the light emitting diode, and the receiving operation is controlled by Di and CLK, here, for convenience of description, two control MCUs 22 are respectively called as MCU1 and MCU2, Di1 is provided by one of the control MCUs 22, the cascade lower level Di is provided by the output Do of the chip at the upper level, all the receiving chips share a clock and are provided by the control MCU1, and the MCU2 monitors. Received light current signals of the light emitting diode are amplified by a receiving chip and differentially divided into SN and SP current signals to be output, the SN and the SP are processed by a trigger Signal Processing circuit Signal Processing to obtain serial signals and are transmitted to a serial Signal Processing single chip microcomputer Signal Processing MCU, the serial signals are analyzed by the serial Signal Processing single chip microcomputer and then are output to the MCU1 and the MCU2 in parallel, the MCU1 and the MCU2 start receiving work according to trigger signals at the output end of the trigger Signal Processing circuit, and control output circuits are controlled according to received parallel data.

The infrared receiver 2 is a dual-channel system, the serial signal processing single chip microcomputer completes failure diagnosis of more than 95% of received signal transmission through analysis, the parallel signals are transmitted to the MCU1 and the MCU2 in a dual-channel mode, the MCU1 and the MCU2 control output of the two channels respectively, and the MCU1 and the MCU2 share a parallel port to carry out information exchange and mutual monitoring. In addition, a watchdog circuit WDT is designed for the MCU1 and the MCU2 respectively to monitor the working conditions of the MCU1 and the MCU2 respectively, the output of the watchdog circuit WDT is directly connected to the driving circuit EN to realize safe output of a corresponding control output circuit through the watchdog circuit, and safe output is ensured when the MCU1 and the MCU2 work wrongly.

Output control principle of the present embodiment:

as shown in fig. 6, the output is a dual-channel output of cat.4 architecture, and the dual-channel control module controls the output of the overvoltage/undervoltage determination signal, the OSSD output control circuit, and the dongle monitoring circuit. The control process of the OSSD is a dynamic real-time monitoring process: during normal operation, a short signal change is made, here by a short circuit of 50us being output to the discharge control module, and by determining whether there is a current output, to check whether the circuit is intact or faulty.

The MCU1 and the MCU2 jointly output dynamic signals for voltage detection, overvoltage and undervoltage judgment signals and WDT output control OSSD output MOS tubes Q17 and Q11, and two I/O ports of the MCU1 respectively control an OSSD1 output control MOS tube Q17 and an OSSD1 unloading MOS tube Q20. The control WDT output of the MOS transistor Q17 has a priority control right, the over-voltage and under-voltage judgment signal has a second priority control right, and the OSSD 1C 1 has a third priority control right. The MCU1 receives the output MOS transistor Q17 of the control OSSD1 and the overcurrent to obtain the corresponding control feedback signal OSSD 1F 1, and receives the unloading MOS transistor Q20 of the OSSD1 and the corresponding control feedback signal OSSD 1F 2. And the single chip microcomputer can detect the problem of either OSSD output control or unloading control. MCU2 controls OSSD2 in a similar manner. And MCU1 and MCU2 have the parallel port to communicate each other, realize the software interlocking, when guaranteeing that any channel goes wrong, another channel can both know and control the output of this channel control.

Preferably, the first power supply module 11 and the second power supply module 12 have two corresponding connection modes, and two different coded working channels can be selected, so that when two or more safety light curtains are placed adjacent to each other, different power supply connection modes are selected to enable the two or more safety light curtains to work by using light pulse signals with different frequencies, and therefore mutual influence can be suppressed. The infrared transmitter 1 transmits the transmission signal through a control cycle of a fixed clock. The infrared receiver 2 receives the optical signal and transmits the optical signal to the dual-channel control module through signal processing, and the dual-channel control module controls dual output according to the received signal. The two control MCUs 22 of the dual-channel control module communicate with each other through parallel ports and display working states, alarm information and the like through the communication channel and the display module 27 in the communication channel.

In order to save control resources, improve the stability of a circuit, reduce the volume of hardware and realize serial cyclic control of transmission and reception, a special transmission chip iC-NXL and a special reception chip iC-NK of iC-Haus are respectively selected for transmission and reception, and shift registers contained in the two special chips can realize the one-by-one work of the chips and the one-by-one transmission and reception of signals through CLK clock signals. The chips are connected in cascade in a Do and Di connection mode, the transmitting chip and the receiving chip finish transmitting and receiving work when CLK and Di ends of the chips are at low level respectively, and switching of transmitting channels or chips of a Lamp (LED) is finished through a rising edge and a falling edge of CLK, so that the cyclic work can be controlled only by providing a clock signal and a Di signal.

The software design method of the embodiment is as follows:

the control system software comprises a transmitting control program and a receiving control program, and is realized in a Keil environment by adopting C language.

The most critical in software design is how to achieve synchronous operation of transmission and reception. As shown in fig. 7, after initialization, the infrared transmitter 1 starts a transmission clock block, and controls a time sequence through a timer and a counter, and cyclically outputs a certain number of high and low levels as a transmission clock at a certain period, and the controller outputs a transmission signal at the low level, and the transmission signal is transmitted during the duration of the transmission clock at the low level after being processed. The counter determines the start and the end of the cycle according to the number counting of the emitting lamps, the timer is responsible for the timing of the time of the clock duty ratio, and the Di1 realizes the connection of the end and the start of the cycle work of the emitting chip by delaying Do3 through clock control.

In the infrared receiver 2, after initialization is completed, the receiving chips are controlled to receive CLK and Di continuously at low level, the receiving chips wait for receiving a head lamp synchronous signal, after the head lamp synchronous signal is received, the head lamp synchronous signal is processed by the trigger signal processing circuit to be used as a trigger signal and sent to the dual-channel control module, the MCU1 starts a clock program block and a Di1 program block after scanning and receiving, CLK and Di circulation is started, synchronization is completed, and then periodic receiving activity is performed. The control of CLK and Di is also realized by a counter and a timer. The dual-channel control module respectively judges the received and processed infrared signals and checks whether the received data meet the requirements. And carrying out dynamic diagnosis compound control on the output, wherein diagnosis and shielding simultaneously participate in controlling the output.

The infrared transmitter 1 of this embodiment adopts a scheme of performing signal coding modulation on each optical path, and each path of coded signals are cyclically and sequentially transmitted through strict time sequence control, and scanning monitoring is performed on the transmission period. The infrared receiver 2 adopts a dual-channel structure, after the synchronization is realized through the confirmation of the first path of transmitting coded signals, the signals are received under the same strict time sequence control, the received signals are processed and transmitted to a dual-channel control module machine to judge whether each path of transmitting light is blocked or wrong, and simultaneously, each control MCU carries out real-time diagnosis on the circuit, thereby reliably controlling two paths of safety output, realizing the capability of resisting 100 and 000LUX (LuX) high external light interference and strong EMC (electro magnetic compatibility) interference, and solving the requirement of the existing market on the high reliability of a safety control field.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Although infrared emitters 1 are used more herein; a first power supply module 11; a transmit MCU 12; a transmission signal processing circuit 13; a signal transmission circuit 14; a periodic scanning module 15; an infrared receiver 2; a second power supply module 21; a control MCU 22; an output control circuit 23; a signal receiving circuit 24; the received signal processing circuit 25; an output detection circuit 26; display module 27, etc., but does not exclude the possibility of using other terms. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any additional limitations that may be imposed by the spirit of the present invention.

Claims

1. A safety light curtain comprises an infrared transmitter (1) and an infrared receiver (2), wherein the infrared transmitter (1) comprises a first power module (11) and a transmitting module for transmitting infrared signals, and is characterized in that the infrared receiver (2) comprises a second power module (21), a signal receiving and processing module and a double-channel control module which are sequentially connected, each control module comprises a control MCU (22), an output control circuit (23) and an output detection circuit (26), the two control MCUs (22) are connected with the signal receiving and processing module, the two control MCUs (22) are respectively connected with the output control circuit (23) of the corresponding channel to output control signals to the output control circuit (23), and each output detection circuit (26) is respectively connected with the output control circuit (23) and the control MCU (22) of the corresponding channel, so that each channel can detect the fault of the output control circuit (23) through the output detection circuit (26) and feed back the fault to the corresponding control MCU (22).

2. The safety light curtain according to claim 1, wherein the output control circuit (23) comprises a first MOS transistor and a driving circuit for driving the first MOS transistor, and the control signal of the control MCU (22) is output to the driving circuit.

3. The safety light curtain of claim 2, wherein the voltage monitoring terminals of the two control MCUs (22) are respectively connected to the comparison circuit to respectively monitor the two control MCUs (22) for undervoltage and overvoltage, the comparison circuit connects the voltage monitoring output terminals of the two control MCUs (22) to the and circuit, and the output terminals of the and circuit are respectively connected to the two driving circuits of the two channel control module to realize the safety output of the two output control circuits (23) through the undervoltage and overvoltage signals of any control MCUs (22).

4. The safety light curtain of claim 3, wherein the two control MCUs (22) are connected to watchdog circuits respectively connected to the respective channels, and the two watchdog circuits are respectively connected to the corresponding channel driving circuits to realize the safety output to the corresponding output control circuits (23) through the watchdog circuits;

the two paths of control MCUs (22) are respectively connected with unloading control modules of respective channels, each unloading control module comprises a second MOS (metal oxide semiconductor) tube, and the second MOS tubes are bidirectionally connected with the control MCUs (22) of the corresponding channels so that the corresponding control MCUs (22) can carry out unloading control output self-checking.

5. The safety light curtain of claim 1, wherein the two control MCUs (22) are connected through parallel port communication for information exchange and two-way mutual detection, and a display module (27) is connected to the parallel port.

6. The safety light curtain according to any one of claims 2 to 5, wherein the transmitting module comprises a transmitting MCU (12) and a transmitting signal processing circuit (13) connected to the transmitting MCU (12), the transmitting signal processing circuit (13) is connected with a signal transmitting circuit (14), and a clock end of the signal transmitting circuit (14) is connected to the transmitting MCU (12) to control the start of transmission through the transmitting MCU (12).

7. A safety light curtain as claimed in claim 6, characterised in that the signal transmission circuit (14) comprises a plurality of emitting chips, each emitting chip having a plurality of light emitting diodes connected thereto for transmitting the emission signals in the form of infrared signals through the light emitting diodes;

and the transmitting MCU (12) outputs a preset code for each light emitting diode through the transmitting signal processing circuit (13) so that the transmitting signal processing circuit (13) transmits infrared signals in a light code form.

8. The safety light curtain of claim 7, wherein the clock terminal of each emitting chip is connected to the emitting MCU (12), the emitting chips are connected in cascade by means of connection of Do and Di, and the Di terminal of the first emitting chip and the Do terminal of the last emitting chip are connected to the emitting MCU (12) through the period scanning module (15) to perform control and monitoring of the cycle period through the emitting MCU (12).

9. The safety light curtain according to claim 8, wherein the signal receiving and processing module comprises a signal receiving circuit (24) and a received signal processing circuit (25), the signal receiving circuit (24) comprises a plurality of receiving chips for receiving infrared signals, the output ends of the receiving chips are connected to the received signal processing circuit (25), the received signal processing circuit (25) comprises a trigger signal processing circuit and a serial signal processing single chip microcomputer which are connected in sequence, and the trigger signal processing circuit and the serial signal processing single chip microcomputer are connected to the two MCUs to output trigger signals to the two control MCUs (22) and output the trigger signals in parallel.

10. The safety light curtain of claim 9, wherein the clock terminals of the plurality of receiving chips are connected to the two control MCUs (22), and one control MCU (22) provides a clock signal, and the other control MCU (22) monitors;

the receiving chips are connected in cascade in a Do and Di connection mode, and the Di end of the first receiving chip is connected to at least one of the two paths of control MCUs (22) so as to control the beginning of a receiving period through the control MCU (22).