Safety light curtain with simplified circuit

Abstract

The invention discloses a safety light curtain with a simplified circuit, which relates to the technical field of photoelectricity and comprises a transmitting end, a receiving end and a synchronous circuit, the transmitting end, the receiving end and the synchronous circuit share common modules such as a master control module, a power supply module, a display module and a watchdog module, the transmitting end comprises a control circuit and a light transmitting tube, and the receiving end is additionally provided with a signal amplification circuit and an output circuit. The control circuit adopts a matrix structure formed by 74HC595 shift registers, so that the use amount of shift chips and triodes is greatly reduced, the circuit is simplified, and the cost is reduced; the power supply circuit supports DC9-30V wide voltage input, and has multiple protection and strong anti-interference performance; the output circuit provides a plurality of signal output modes to adapt to different external devices. According to the invention, by optimizing the circuit design, the structure is simplified, the cost is saved, the adaptability is improved on the premise of ensuring accurate detection of object shielding and stable work, and the system is suitable for various industrial and civil safety protection scenes.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, and in particular to a simplified circuit safety light curtain. Background Technology

[0002] As a core safety protection device in the field of optoelectronic technology, safety light curtains are widely used in industrial production protection, highway vehicle inspection, elevator door control, metallurgical production and other scenarios. They form an invisible light curtain through infrared beams from the transmitting and receiving ends. When the light curtain is blocked, a shutdown signal is triggered to ensure the safety of personnel and equipment.

[0003] Its traditional structure consists of a transmitter, a receiver, and a dedicated synchronization cable. Detection is achieved by scanning the optical transmitter and receiver one by one. However, the control circuit design is complex and requires a large number of shifting chips and transistors, which not only leads to high component costs and difficult PCB layout, but also increases the circuit failure rate.

[0004] Meanwhile, industrial environments present challenges such as power supply fluctuations and electromagnetic interference. Traditional safety light curtains lack sufficient power adaptability and anti-interference capabilities, and their single output mode makes them difficult to adapt to different external devices. Therefore, there is an urgent need for a safety light curtain that simplifies the control circuit structure, reduces costs, and simultaneously offers wide voltage input, strong anti-interference capabilities, and multiple output modes to meet the practical needs of industrial scenarios. Summary of the Invention

[0005] To address the technical problems existing in the background art, the present invention proposes a simplified circuit safety light curtain.

[0006] This invention proposes a simplified circuit safety light curtain, comprising a transmitter, a receiver, and a synchronization circuit connecting the transmitter and receiver. The transmitter includes a main control circuit, a control circuit, and a light emitting tube. The receiver includes a main control circuit, a control circuit, a light receiving tube, a signal amplification circuit, and an output circuit. The main control circuit, synchronization circuit, power supply circuit, display circuit, and watchdog circuit of the transmitter and receiver are completely identical in structure. The main control circuit serves as the core processing unit of the entire safety light curtain, coordinating the working timing and data interaction of each circuit module. The synchronization circuit is used to realize signal synchronization and communication connection between the transmitter and receiver, ensuring precise matching of the corresponding working timing of the light emitting tube and the light receiving tube.

[0007] Furthermore, the main control circuit includes a microcontroller, capacitors, inductors, resistors, and a crystal oscillator. The capacitors are used to filter out noise signals in the circuit and stabilize the power supply voltage of the main control circuit. The inductors are used to suppress current surges and protect core components such as the microcontroller. The resistors are used to adjust the current in the circuit and realize signal voltage division and current limiting functions. The crystal oscillator is used to provide a stable clock signal for the microcontroller and ensure the stability of the operation and control rhythm of the main control circuit.

[0008] Furthermore, the power supply circuit is electrically connected to the main control circuit, control circuit, signal amplification circuit, output circuit, and synchronization circuit. The power supply circuit provides a stable operating power supply for the entire safety light curtain device. Its built-in TVS diode is used to suppress transient overvoltages and protect the circuit from surge impacts. The self-resetting fuse is used to automatically disconnect when an overcurrent fault occurs in the circuit and automatically resume conduction after the fault is cleared. The π-type filter circuit is used to filter high-frequency interference signals in the power supply. At the same time, the power supply circuit has reverse connection protection, overvoltage protection, and electromagnetic compatibility design, and the input voltage range is a wide voltage input of DC9 to 30V.

[0009] Furthermore, the display circuit is connected to the main control circuit. The display circuit is used to intuitively output the current working status of the safety light curtain through LEDs, so that staff can observe the operation of the device in real time. The watchdog circuit is connected to the main control circuit. The watchdog circuit is used to automatically trigger the main control circuit to restart when the MCU program runs away or an abnormal freeze occurs, so as to ensure the continuous and stable operation of the safety light curtain.

[0010] Furthermore, the control circuit of the transmitter consists of multiple 74HC595 shift registers of the same model. The 74HC595 shift registers are used to convert serial input data into parallel output and expand the number of control ports through cascading. The control circuit of the transmitter is used to receive control signals from the main control circuit and realize the turn-on and turn-off control of the light emitting diode. The light emitting diode is used to emit infrared or visible light signals when it is turned on, and the light emitting diode is selected from infrared light-emitting diodes or visible light-emitting diodes.

[0011] Furthermore, the control circuit of the receiving end is also composed of multiple 74HC595 shift registers. The control circuit of the receiving end is used to receive instructions from the main control circuit and control the optical receiving tubes at the corresponding positions to turn on in turn to receive optical signals. The optical receiving tubes are used to convert the received optical signals into weak electrical signals. The signal amplification circuit is connected between the optical receiving tubes and the main control circuit. The signal amplification circuit is used to amplify the weak electrical signals output by the optical receiving tubes to an amplitude that the MCU can recognize and process.

[0012] Furthermore, the output circuit is connected to the main control circuit of the receiving end. The output circuit is used to convert the detection result of the main control circuit into a corresponding signal and output it to the external device. The signal output mode of the output circuit includes NPN switch signal output, PNP switch signal output, 4-20mA current analog output, 0-10V voltage analog output, RS232 output, or RS485 output. The RS485 output circuit is used to achieve long-distance, interference-resistant signal transmission through differential signal transmission, and the RS232 output circuit is used to achieve signal interaction with the external device through the serial data communication interface standard.

[0013] Furthermore, the control circuit adopts a matrix control structure, with two 74HC595 shift registers forming a group of 16 output ports as row control terminals, and several other 74HC595 shift registers with 8 output ports as column control terminals. The matrix control structure is used to achieve the coordinated control of the row control terminals and column control terminals, so that only one optical transmitter or optical receiver is selected to work at any given time, thereby greatly reducing the number of shift registers and transistors used and simplifying the circuit layout.

[0014] Furthermore, the transistors in the control circuit include PNP transistors and NPN transistors, or P-MOSFETs and N-MOSFETs. Transistors numbered less than 17 are PNP transistors or P-MOSFETs, used to control the power supply path of the light emitting diode or light receiving diode. Transistors numbered 17 or higher are NPN transistors or N-MOSFETs, used to control the grounding path of the light emitting diode or light receiving diode through a current-limiting resistor. The transistors are used to amplify the control signal to realize the conduction and cutoff control of the light emitting diode or light receiving diode.

[0015] Furthermore, the microcontroller at the transmitting end controls the optical emitting tubes to emit optical signals in turn through the control circuit, and the microcontroller at the receiving end obtains the working timing of the transmitting end through the synchronization circuit, and synchronously controls the optical receiving tubes to receive optical signals in turn. The microcontroller at the receiving end is used to determine the reception status of the optical signal through the amplified electrical signal, and then determine whether there is an object blocking between the transmitting end and the receiving end, thereby realizing the object detection function of the safety protection area.

[0016] The beneficial effects of this invention are as follows: By using a matrix control circuit composed of 74HC595 shift registers, the number of shift chips and transistors used is greatly reduced, significantly simplifying the circuit layout, reducing component costs and PCB design difficulty. At the same time, by integrating a power supply circuit with wide voltage input, multiple protections and strong anti-interference design, a precise synchronization circuit, a stable and reliable watchdog circuit, and multiple output circuits adapted to different external devices, the invention achieves multiple goals of "simplified structure, cost saving, and improved adaptability" while ensuring accurate detection of object obstruction, continuous and stable operation, and adaptability to harsh industrial environments. This is more in line with the actual application needs of industrial scenarios. Attached Figure Description

[0017] Figure 1 This is a structural block diagram of the present invention; Figure 2 This is a schematic diagram illustrating the principle of the present invention; Figure 3 This is a schematic diagram of the matrix control circuit (74HC595 shift register cascaded) in this invention; Figure 4This is a schematic diagram of the transmitter control circuit (transistor connected to optical transmitter) in this invention; Figure 5 for Figure 4 A partially enlarged schematic diagram of the transmitter control circuit. Figure 1 ; Figure 6 for Figure 4 A partially enlarged schematic diagram of the transmitter control circuit. Figure 2 ; Figure 7 for Figure 4 A partially enlarged schematic diagram of the transmitter control circuit. Figure 3 ; Figure 8 for Figure 4 A partially enlarged schematic diagram of the transmitter control circuit. Figure 4 ; Figure 9 for Figure 4 A partially enlarged schematic diagram of the transmitter control circuit. Figure 5 . Detailed Implementation

[0018] Reference Figure 1-2 This invention proposes a simplified circuit safety light curtain. This safety light curtain achieves circuit simplification and cost reduction while ensuring safety detection functionality by optimizing the control circuit structure and integrating common modules. Specific implementation details are as follows: The safety light curtain includes a transmitter 101 and a receiver 201. The two communicate with each other via a synchronous cable (transmitter synchronous cable 102 and receiver synchronous cable 202) to form an invisible light curtain detection system. The transmitter 101 is responsible for transmitting light signals, and the receiver 201 is responsible for receiving light signals and completing detection and signal output. The whole device is suitable for various scenarios such as industrial production safety protection, highway toll station vehicle detection, and elevator door control. 1. The transmitter 101 and receiver 201 share completely identical common modules, including the main control circuit, power supply circuit, display circuit, watchdog circuit, and synchronization circuit. The specific structure and function of each module are as follows: 1.1 Main Control Circuit: As the core processing unit of the entire device, it uses a microcontroller (MCU) as its core, and is equipped with capacitors, inductors, resistors, and a crystal oscillator to form a complete control loop. Among them, ceramic filter capacitors are used to filter out noise signals in the power supply line and stabilize the operating voltage of the microcontroller; surface-mount power inductors are used to suppress sudden current changes in the circuit and avoid damage to the microcontroller from peak currents; precision carbon film resistors are used, and through proper selection, signal voltage division and current limiting are achieved to ensure that the amplitude of the microcontroller's input and output signals is within a safe range; an 8MHz passive crystal oscillator is used to provide a stable clock signal for the microcontroller, ensuring that the operation rhythm and control timing are precise and controllable. 1.2 Power Supply Circuit: Electrically connected to the main control circuit, control circuit, and other functional circuits, it adopts a wide DC 9-30V input voltage design to adapt to different power supply environments in industrial settings. The circuit incorporates a built-in TVS transient voltage suppressor diode (SMBJ6.5CA) to absorb transient overvoltages and prevent surge damage to components. A JK60-010 resettable fuse automatically disconnects the power supply in case of an overcurrent fault and automatically resumes conduction after the fault is cleared, requiring no manual replacement. The π-type filter circuit, composed of electrolytic capacitors, ceramic capacitors, and inductors, effectively filters high-frequency interference signals in the power supply, outputting a clean and stable DC voltage. Additionally, the power supply circuit is designed with a reverse polarity protection diode to prevent circuit burnout due to reversed polarity. Overall, it possesses good electromagnetic compatibility and meets the requirements for use in industrial electromagnetic environments. 1.3 Display Circuit: Three LEDs are used as display devices, corresponding to three states: normal power supply, normal operation, and obstruction alarm. The LEDs are connected to the I / O port of the main control circuit through current-limiting resistors. When the device is powered on and the power supply is normal, the power indicator (green) is constantly lit; when the device is in normal operation without obstruction, the operation indicator (blue) is constantly lit; when an object is detected to obstruct the light curtain, the alarm indicator (red) flashes, and at the same time, a stop signal is sent to external equipment through the output circuit, so that the staff can intuitively grasp the operating status of the device. 1.4 Watchdog Circuit: The MAX813L watchdog chip is selected. Its reset pin is connected to the reset terminal of the microcontroller. The timer pin is configured with a resistor and capacitor to set the reset timeout to 1.6 seconds. When the microcontroller program runs away or freezes, if the watchdog chip does not receive the feed signal within the set time, it will automatically output a reset signal to trigger the main control circuit to restart, ensuring the device continues to work stably and avoiding the failure of safety protection due to program abnormalities. 1.5 Synchronization Circuit: Differential signal transmission is adopted. The synchronization circuits of the transmitter and receiver are connected through two signal lines (A line and B line) to realize the timing synchronization and signal interaction between the two parties. The core of the synchronization circuit is to convert the optical transmission timing signal of the transmitter into a differential signal for transmission. After receiving it, the receiver restores it into a timing control signal to ensure that the optical receiver tube of the receiver and the optical transmitter tube of the transmitter are in one-to-one correspondence and conduction, avoiding detection errors caused by signal misalignment. At the same time, the differential transmission method enhances the anti-electromagnetic interference capability and is suitable for industrial strong interference environments.

[0019] 2. The differentiated modules of transmitter 101 include control circuits and optical emission tubes, and their specific structure and implementation are as follows: 2.1 Control Circuit: A matrix control structure is adopted, with the core component being the 74HC595 shift register. This chip is an 8-bit shift register with tri-state output, supporting serial input to parallel output conversion, and its control ports can be expanded through cascading. In this embodiment, the control circuit consists of two 74HC595s as row control chips and several 74HC595s as column control chips. The QA to QH output ports of the two row control chips form a total of 16 row control terminals. Each row control terminal is connected to one PN pin through a current-limiting resistor. The base of the P-type transistor and the collector of the PNP transistor are connected to the positive terminal of the light-emitting diode, and the emitter is connected to the power supply VCC. Each output port of the column control chip is connected to the base of an NPN transistor through a current-limiting resistor. The emitter of the NPN transistor is grounded, and the collector is connected to the negative terminal of the light-emitting diode through a current-limiting resistor. The main control circuit outputs a serial signal to the shift register to realize the coordinated selection of the row control terminal and the column control terminal, ensuring that only one light-emitting diode is turned on and emits light at any given time, avoiding signal interference caused by multiple light-emitting diodes working at the same time. 2.2 Light Emitting Diodes: Infrared light-emitting diodes (model IR333-A) are selected, with an emission wavelength of 940nm, an operating current of 20mA, and an emission power of 10mW. The light emitting diodes are evenly arranged along the length of the emitting end shell, with a spacing of 20mm between adjacent light emitting diodes, for a total of 128 light emitting diodes, forming a light curtain area with a height of 2.54m. The positive terminals of all light emitting diodes are grouped into groups of 8 and connected to the collectors of the corresponding PNP transistors in the row control circuit, while the negative terminals are grouped into groups of 16 and connected to the collectors of the corresponding NPN transistors in the column control circuit. Infrared light is emitted in turn through matrix control. 3. The differentiated module of receiver 201 includes a control circuit, an optical receiver tube, a signal amplification circuit, and an output circuit. The specific structure and implementation are as follows: 3.1 Control Circuit: The control circuit structure is completely consistent with that of the transmitter, also using a matrix control structure composed of 74HC595 shift registers. The only difference is that the target device is changed to the optical receiver tube. The output of the row control chip is connected to a PNP transistor to control the power supply of the optical receiver tube; the output of the column control chip is connected to an NPN transistor to control the signal output path of the optical receiver tube. Through timing signals synchronized with the transmitter, the optical receiver tube and the optical transmitter tube are turned on one-to-one to ensure accurate reception of the optical signal of the corresponding channel. 3.2. Optical Receiver: An infrared receiving diode (model PT334-6B) is selected. Its receiving wavelength matches the emission wavelength of the optical emitter (940nm). The dark current is less than 10nA and the response time is less than 2μs. The optical receivers are evenly arranged along the length of the receiver end shell, and their positions correspond one-to-one with the optical emitters at the transmitter end. The adjacent spacing is also 20mm. A total of 128 optical receivers are set. The positive terminal of the optical receiver is connected to the collector of the NPN transistor in the column control circuit through a current-limiting resistor, and the negative terminal is connected to the input terminal of the signal amplification circuit. When the optical receiver receives an infrared signal, it will convert the light signal into a weak current signal (μA level) and output it to the signal amplification circuit.

[0020] 3.3 Signal Amplification Circuit: A two-stage operational amplifier circuit is used. The first stage uses an OPA320 high-precision operational amplifier to form a non-inverting amplifier circuit with a magnification factor of 100, which converts the weak current signal output by the photodetector into a voltage signal and amplifies it initially. The second stage uses an LM358 operational amplifier to form a differential amplifier circuit with a magnification factor of 10, which further amplifies the signal and suppresses common-mode interference, ultimately amplifying the signal to a voltage range of 0-3.3V (adapting to the input range of the microcontroller's ADC). The output of the amplifier circuit is connected to the ADC sampling pin of the microcontroller. The microcontroller determines whether the corresponding channel has received an optical signal by acquiring the amplified voltage signal.

[0021] 3.4 Output Circuit: This embodiment provides multiple output methods, which users can choose according to their actual needs, specifically including: 3.4.1 NPN Switch Output: An NPN transistor is used as the switching device, with the collector as the output terminal and the emitter grounded. When an obstruction is detected, the transistor conducts and outputs a low-level signal (≤0.3V). When there is no obstruction, the transistor is cut off and outputs a high-level signal (≥VCC-0.3V). It is compatible with controllers with external NPN inputs. 3.4.2 PNP Switch Output: A PNP transistor is used as the switching device. The emitter is connected to the power supply VCC, and the collector is used as the output terminal. When an obstruction is detected, the transistor is turned on and outputs a high-level signal (≥VCC-0.3V). When there is no obstruction, the transistor is turned off and outputs a low-level signal (≤0.3V). It is compatible with controllers with external PNP input. 3.4.3 4~20mA analog current output: The XTR111 current transmitter chip is used to convert the digital signal output by the microcontroller into a 4~20mA current signal, where 4mA corresponds to the unobstructed state, 20mA corresponds to the fully obstructed state, and the intermediate state is output linearly according to the obstruction ratio, which is suitable for industrial control systems that require analog signals. 3.4.4 RS485 Output: The MAX485 chip is used as a differential transceiver to convert the UART signal of the microcontroller into an RS485 differential signal output. The communication baud rate is set to 9600bps, and the data format is 8 data bits, 1 stop bit, and no parity bit. It supports long-distance communication with PLCs, industrial control computers and other equipment, with a transmission distance of up to 1200 meters. 3.4.5 RS232 Output: A MAX232 chip is used for level conversion, converting the microcontroller's TTL level to the RS232 standard level for communication with nearby computers or serial devices, with a transmission distance not exceeding 15 meters. 4. The working process of this simplified circuit safety light curtain is divided into three stages: power-on initialization, synchronous calibration, and cyclic scanning detection. The specific implementation is as follows: 4.1 Power-on Initialization: After the device is connected to a DC24V power supply, the power supply circuit outputs stable 5V and 3.3V voltages after passing through a π-type filter and TVS diode protection, which power the control circuit and microcontroller respectively; the main control circuit completes initialization, configuring parameters such as I / O ports, ADC sampling, and UART communication; the power indicator light of the display circuit is constantly on, and the working indicator light flashes; the watchdog circuit starts working, and the microcontroller sends a watchdog feed signal every 500ms; the synchronization circuit sends a synchronization calibration signal to the receiver to complete the timing synchronization between the transmitter and receiver.

[0022] 4.2 Synchronous Calibration: The transmitter microcontroller sends a calibration pulse signal to the receiver through a synchronization circuit. Upon receiving the signal, the receiver sends a response signal. The main control circuit adjusts the timing deviation between optical emission and optical reception based on the signal transmission delay to ensure that when the first optical transmitter tube is turned on, the corresponding first optical receiver tube is turned on synchronously. The timing calibration of all 128 channels is completed in sequence. After calibration, the indicator light changes from flashing to solid, and the device enters the normal detection state.

[0023] 4.3 Cyclic Scan Detection: After calibration, the device enters cyclic scan mode with a scan cycle set to 10ms. The transmitter microcontroller sequentially selects each optical transmitter tube through the control circuit, causing it to emit infrared pulse signals with a pulse width of 10μs. Simultaneously, the receiver microcontroller selects the corresponding optical receiver tube through synchronous timing. The optical receiver tube converts the received optical signal into a weak electrical signal, which is amplified by the signal amplification circuit and input to the microcontroller's ADC port. The microcontroller samples and judges the amplified signal. When the sampling voltage is greater than 0.5V, it is determined that the channel is unobstructed; when the sampling voltage is less than 0.1V, it is determined that the channel is obstructed. If all channels are unobstructed, the device maintains normal operation, and the output circuit continuously outputs a normal operation signal. If any channel is detected to be obstructed, the microcontroller immediately controls the alarm indicator to flash and simultaneously sends a stop signal to external devices through the output circuit. Upon receiving the signal, the external devices stop operating to prevent injury to personnel or objects. When the obstruction is removed, the device automatically returns to normal operation, the alarm indicator turns off, and the output circuit resumes normal signal output.

[0024] This embodiment significantly reduces the number of shift registers and transistors used through a matrix control structure. Taking 128 optical transmitters / receivers as an example, a conventional solution requires 16 shift registers and 128 transistors, while this solution only requires 3 shift registers and 24 transistors, reducing component costs to 7.8% of the original. At the same time, it simplifies the circuit layout, reduces the difficulty of PCB design and production costs, and ensures the stability and detection accuracy of the device in harsh industrial environments by optimizing the power supply circuit, synchronization circuit and signal amplification circuit. This achieves the core objectives of "simplified circuit, cost-saving and performance-assured".

[0025] Reference Figure 3 In a simplified safety light curtain, multiple shift chips such as the 74HC595 are used to form a matrix control. The eight output ports (QA-QH) of these shift chips are used, with two chips grouped together to form 2*8=16 output ports for row control. The remaining eight output ports are used for column control. Each optical transmitter / receiver is simultaneously controlled by one output port from each of the shift chips in the row and column. Only one optical transmitter / receiver is selected at any given time. Three shift chips can control 16*8=128 optical transmitters / receivers. Adding one more shift chip allows for the control of an additional 16*8=128 optical transmitters / receivers. An example of a transmitter control circuit is provided below. All LEDan LEDs are controlled by the first 74HC595, and all LEDbn LEDs are controlled by the second 74HC595, where n is a natural number. LEDa1 is controlled simultaneously by the QA output ports of the first and third 74HC595 chipsets. LEDa2 is controlled simultaneously by the QB output of the first 74HC595 and the QA output of the third 74HC595. LEDa3 is controlled simultaneously by the QC output of the first 74HC595 and the QA output of the third 74HC595. LEDa4 is controlled simultaneously by the QD output of the first 74HC595 and the QA output of the third 74HC595. LEDa5 is controlled simultaneously by the QE output of the first 74HC595 and the QA output of the third 74HC595. LEDa6 is controlled simultaneously by the QF output of the first 74HC595 and the QA output of the third 74HC595. LEDa7 is controlled simultaneously by the QG output of the first 74HC595 and the QA output of the third 74HC595. LEDa8 is controlled simultaneously by the QH output of the first 74HC595 and the QA output of the third 74HC595. LEDa9 is controlled simultaneously by the QA output of the first 74HC595 and the QB output of the third 74HC595. LEDa10 is controlled simultaneously by the QB output ports of the first and third 74HC595 chipsets. LEDa11 is controlled simultaneously by the QC output of the first 74HC595 and the QB output of the third 74HC595. LEDa12 is controlled simultaneously by the QD output of the first 74HC595 and the QB output of the third 74HC595. LEDa13 is controlled simultaneously by the QE output of the first 74HC595 and the QB output of the third 74HC595. LEDa14 is controlled simultaneously by the QF output of the first 74HC595 and the QB output of the third 74HC595. LEDa15 is controlled simultaneously by the QG output of the first 74HC595 and the QB output of the third 74HC595. LEDa16 is controlled simultaneously by the QH output of the first 74HC595 and the QB output of the third 74HC595. LEDa17 is controlled simultaneously by the QA output of the first 74HC595 and the QC output of the third 74HC595. LEDa18 is controlled simultaneously by the QB output of the first 74HC595 and the QC output of the third 74HC595. … LEDa25 is controlled simultaneously by the QA output of the first 74HC595 and the QD output of the third 74HC595. LEDa26 is controlled simultaneously by the QB output of the first 74HC595 and the QD output of the third 74HC595. … LEDa63 is controlled simultaneously by the QG output of the first 74HC595 and the QH output of the third 74HC595. LEDa64 is controlled simultaneously by the QH output ports of the first and third 74HC595 chipsets. The LEDa65 is controlled simultaneously by the QA output ports of the first and fourth 74HC595 chipsets. The LEDa66 is controlled simultaneously by the QB output of the first 74HC595 and the QA output of the fourth 74HC595. … LEDa127 is controlled simultaneously by the QG output port of the first 74HC595 and the QH output port of the fourth 74HC595. LEDa128 is controlled simultaneously by the QH output ports of the first and fourth 74HC595 chipsets. LEDa129 is controlled simultaneously by the QA output ports of the first and fifth 74HC595 chipsets. The LEDa130 is controlled simultaneously by the QB output of the first 74HC595 and the QA output of the fifth 74HC595. … LEDs a1~a64 are controlled simultaneously by the first and third 74HC595 chips; LEDs b1~b64 are controlled simultaneously by the second and third 74HC595 chips; LEDs a65~a128 are controlled simultaneously by the first and fourth 74HC595 chips; LEDs b65~b128 are controlled simultaneously by the second and fourth 74HC595 chips; LEDs a129~a192 are controlled simultaneously by the first and fifth 74HC595 chips; LEDs b129~b192 are controlled simultaneously by the second and fifth 74HC595 chips; LEDs a193~a256 are controlled simultaneously by the first and sixth 74HC595 chips; LEDs b193~b256 are controlled simultaneously by the second and sixth 74HC595 chips; LEDs a257~a320 are controlled simultaneously by the first and seventh 74HC595 chips; LEDs b257~b320 are controlled simultaneously by the second and seventh 74HC595 chips; … Reference Figure 4-9 In a simplified safety light curtain, taking the transmitter control circuit as an example: the 16 output ports of two 74HC595 shift chips are connected to the bases of 16 transistors respectively. The collectors of these 16 transistors are connected to the positive terminals of multiple light-emitting diodes respectively. The emitters of these 16 transistors are all connected to the power supply. The 8 output ports of a third 74HC595 are connected to the bases of another 8 transistors to control these 8 transistors. The collectors of these 8 transistors are connected to network lamps 1 to 8, lamps 9 to 16... lamps (n-1)*8+1 to (n-1)*8+8, etc. The emitters of these 8 transistors are all grounded.

[0026] The first 74HC595's QA output port is connected to the base of transistor Q1, the first 74HC595's QB output port is connected to the base of transistor Q2, the first 74HC595's QC output port is connected to the base of transistor Q3, the first 74HC595's QD output port is connected to the base of transistor Q4, the first 74HC595's QE output port is connected to the base of transistor Q5, the first 74HC595's QF output port is connected to the base of transistor Q6, the first 74HC595's QG output port is connected to the base of transistor Q7, and the first 74HC595's QH output port is connected to the base of transistor Q8; the second... The QA output of the second 74HC595 is connected to the base of transistor Q9; the QB output of the second 74HC595 is connected to the base of transistor Q10; the QC output of the second 74HC595 is connected to the base of transistor Q11; the QD output of the second 74HC595 is connected to the base of transistor Q12; the QE output of the second 74HC595 is connected to the base of transistor Q13; the QF output of the second 74HC595 is connected to the base of transistor Q14; the QG output of the second 74HC595 is connected to the base of transistor Q15; and the QH output of the second 74HC595 is connected to the base of transistor Q16. The positive terminals of LEDs LEDa1, LEDa9, LEDa17, LEDa25, LEDa33, LEDa41, LEDa49, LEDa57, LEDa65, LEDa73… (the numbers increase by 8 each time) are connected together and connected to the collector of transistor Q1; the positive terminals of LEDs LEDa2, LEDa10, LEDa18, LEDa26, LEDa34, LEDa42, LEDa50, LEDa58, LEDa66, LEDa74… are connected together and connected to the collector of transistor Q2; …; LEDs LEDb1, LE The positive terminals of LEDs Db9, LEDb17, LEDb25, LEDb33, LEDb41, LEDb49, LEDb57, LEDb65, LEDb73… are connected together and connected to the collector of transistor Q9; the positive terminals of LEDs LEDb2, LEDb10, LEDb18, LEDb26, LEDb34, LEDb42, LEDb50, LEDb58, LEDb66, LEDb74… are connected together and connected to the collector of transistor Q10;… and so on, for LEDs LEDam, LEDam+8, LEDam+16, LEDa… The positive terminals of LEDs m+24, LEDam+32, LEDam+40, LEDam+48, LEDam+56, LEDam+64, LEDam+72… (where m is a natural number between 1 and 8) are connected together and connected to the collector of transistor Qm; the positive terminals of LEDs LEDbm, LEDbm+8, LEDbm+16, LEDbm+24, LEDbm+32, LEDbm+40, LEDbm+48, LEDbm+56, LEDbm+64, LEDbm+72… are connected together and connected to the collector of transistor Qm+8; transistor Q1… The emitters of Q16 are all connected to a power supply; the negative terminals of LEDa1~LEDa8 and LEDb1~LEDb8 are connected together, and the network is called Lamp 1~8; the negative terminals of LEDa9~LEDa16 and LEDb9~LEDb16 are connected together, and the network is called Lamp 9~16; and so on, the negative terminals of every 16 transistors of LEDa(n-1)*8+1~LEDa(n-1)*8+8 and LEDb(n-1)*8+1~LEDb(n-1)*8+8 are connected together, and the network is called Lamp (n-1)*8+1~(n-1)*8+8; The third 74HC595's QA output port is connected to the base of transistor Q17, the third 74HC595's QB output port is connected to the base of transistor Q18, the third 74HC595's QC output port is connected to the base of transistor Q19, the third 74HC595's QD output port is connected to the base of transistor Q20, the third 74HC595's QE output port is connected to the base of transistor Q21, the third 74HC595's QF output port is connected to the base of transistor Q22, the third 74HC595's QG output port is connected to the base of transistor Q23, and the third 74HC595's QH output port is connected to the base of transistor Q24. Similarly, the (n+2)th 74HC595's QA output is connected to the base of transistor Qn*16+1, the (n+2)th 74HC595's QB output is connected to the base of transistor Qn*16+2, the (n+2)th 74HC595's QC output is connected to the base of transistor Qn*16+3, and the (n+2)th 74HC595's QD output is connected to the base of transistor Qn*16+4. The QE output of the (n+2)th 74HC595 is connected to the base of transistor Qn*16+5, the QF output of the (n+2)th 74HC595 is connected to the base of transistor Qn*16+6, the QG output of the (n+2)th 74HC595 is connected to the base of transistor Qn*16+7, and the QH output of the (n+2)th 74HC595 is connected to the base of transistor Qn*16+8. Network lamps 1-8 are connected to current-limiting resistor R17, and the other side of current-limiting resistor R17 is connected to the collector of transistor Q17; network lamps 9-16 are connected to current-limiting resistor R18, and the other side of current-limiting resistor R18 is connected to the collector of transistor Q18; ... and so on. Network lamps (n-1)*8+1 to (n-1)*8+8 are first connected to current-limiting resistor Rn+16, and the other side of current-limiting resistor Rn+16 is connected to the emitter of transistor Qn+16. The collectors of all transistors numbered 17 or higher are grounded.

[0027] As one implementation method: all transistors with a number less than 17 are PNP transistors; All transistors numbered 17 or higher are NPN transistors.

[0028] As another implementation: all transistors numbered less than 17 are P-MOSFETs (P-MOS, P-channel Metal Oxide Semiconductor Field Effect Transistor). All transistors numbered 17 or higher are N-MOSFETs (N-MOS, N-channel Metal Oxide Semiconductor Field Effect Transistor).

[0029] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A simplified circuit safety light curtain, characterized by, The application relates to a safety light curtain device, which comprises a transmitting end, a receiving end and a synchronous circuit connecting the transmitting end and the receiving end, the transmitting end comprises a main control circuit, a control circuit and a light transmitting tube, the receiving end comprises a main control circuit, a control circuit, a light receiving tube, a signal amplification circuit and an output circuit, the main control circuits, the synchronous circuits, the power supply circuits, the display circuits and the watchdog circuits of the transmitting end and the receiving end are completely consistent in structure, the main control circuit is used as a core processing unit of the whole safety light curtain, and is used for overall coordinating the working time sequence and data interaction of the circuit modules, the synchronous circuit is used for realizing signal synchronization and communication connection between the transmitting end and the receiving end, and ensuring accurate matching of the working time sequence of the light transmitting tube and the light receiving tube.

2. The simplified circuit safety light curtain according to claim 1, characterized in that The main control circuit comprises a microcontroller, a capacitor, an inductor, a resistor and a crystal oscillator, the capacitor is used for filtering out noise signals in the circuit, stabilizing the power supply voltage of the main control circuit, the inductor is used for inhibiting current mutation and protecting core components such as the microcontroller, the resistor is used for adjusting the current size in the circuit, realizing signal voltage division and current limiting functions, and the crystal oscillator is used for providing a stable clock signal for the microcontroller, guaranteeing the operation and control rhythm of the main control circuit to be stable.

3. The simplified circuit safety light curtain of claim 1, wherein, The power supply circuit is electrically connected with the main control circuit, the control circuit, the signal amplification circuit, the output circuit and the synchronous circuit, the power supply circuit is used for providing a stable working power supply for the whole safety light curtain device, a TVS tube built in the power supply circuit is used for inhibiting transient overvoltage and protecting the circuit from surge impact, a self-restoring fuse is used for automatically disconnecting when overcurrent fault occurs in the circuit, automatically restoring conduction after the fault is eliminated, a pi-type filter circuit is used for filtering high-frequency interference signals in the power supply, meanwhile, the power supply circuit has reverse connection protection, overvoltage protection and electromagnetic compatibility design, and the input voltage range is DC 9-30V wide voltage input.

4. The simplified circuit safety light curtain of claim 1, wherein, The display circuit is connected with the main control circuit, the display circuit is used for directly outputting the current working state of the safety light curtain through an LED, facilitating workers to observe the device running condition in real time, the watchdog circuit is connected with the main control circuit, and the watchdog circuit is used for automatically triggering the main control circuit to restart when the MCU program runs away or abnormally stops, guaranteeing the continuous and stable work of the safety light curtain.

5. The simplified circuit safety light curtain of claim 1, wherein, The control circuit of the transmitting end is composed of a plurality of 74HC595 shift registers of the same type, the 74HC595 shift register is used for converting serial input data into parallel output, and the control port quantity is expanded through a cascade mode, the control circuit of the transmitting end is used for receiving the control signal of the main control circuit, realizing turn-on and turn-off control of the light transmitting tube, the light transmitting tube is used for emitting infrared or visible light signals when turned on, and the light transmitting tube is selected from an infrared light emitting diode or a visible light emitting diode.

6. The simplified circuit safety light curtain of claim 1, wherein, The control circuit of the receiving end is also composed of a plurality of 74HC595 shift registers, the control circuit of the receiving end is used for receiving the instruction of the main control circuit, controlling the light receiving tube at the corresponding position to turn on to receive light signals, the light receiving tube is used for converting the received light signals into weak electric signals, the signal amplification circuit is connected between the light receiving tube and the main control circuit, and the signal amplification circuit is used for amplifying the weak electric signals output by the light receiving tube to the amplitude that can be recognized and processed by the MCU.

7. The simplified circuit safety light curtain of claim 1, wherein, The output circuit is connected with the master control circuit of the receiving end, and the output circuit is used for converting the detection result of the master control circuit into a corresponding signal and outputting the signal to an external device. The signal output mode of the output circuit includes NPN switching value signal output, PNP switching value signal output, 4-20 mA current analog output, 0-10 V voltage analog output, RS232 output or RS485 output. The RS485 output circuit is used for realizing long-distance and anti-interference signal transmission through a differential signal transmission mode, and the RS232 output circuit is used for realizing signal interaction with the external device through a serial data communication interface standard.

8. The simplified circuit safety light curtain according to claim 5 or 6, characterized in that, The control circuit adopts a matrix control structure, and 2 74HC595 shift registers are used as a group to form 16 output ports as row control ends. A plurality of 74HC595 shift registers are used to form 8 output ports as column control ends. The matrix control structure is used for cooperative control of the row control ends and the column control ends to realize work of only one light emitting tube or light receiving tube at a single time, so that the number of shift registers and transistors used is greatly reduced, and the circuit layout is simplified.

9. The simplified circuit safety light curtain according to claim 8, characterized in that, The transistors in the control circuit include PNP transistors and NPN transistors, or P-MOSFET and N-MOSFET. The transistors with numbers less than 17 are PNP transistors or P-MOSFET, which are used for controlling the power supply path of the light emitting tube or the light receiving tube. The transistors with numbers greater than or equal to 17 are NPN transistors or N-MOSFET, which are used for controlling the ground path of the light emitting tube or the light receiving tube through a current limiting resistor. The transistors are used for amplifying the control signal to realize on-off control of the light emitting tube or the light receiving tube.

10. The simplified circuit safety light curtain of claim 1, wherein, The microcontroller of the transmitting end controls the light emitting tube to emit light signals in turn through the control circuit, and the microcontroller of the receiving end obtains the working time sequence of the transmitting end through the synchronization circuit to synchronously control the light receiving tube to receive light signals in turn. The microcontroller of the receiving end is used for judging the reception of the light signal through the amplified electric signal, and then determining whether there is an object shielding between the transmitting end and the receiving end, so as to realize the object detection function of the safety protection area.

Images