Expandable cascade diffuse reflection laser sensor

Abstract

The invention relates to the technical field of optical sensors, in particular to an expandable cascade diffuse reflection laser sensor, which comprises a master device and at least one slave device, the master device and the slave device are communicated through a synchronizing signal and a voltage division sampling signal, and the synchronizing signal and a voltage value are used for controlling the working states of a transmitting end and a receiving end in a time-sharing manner. Compared with the prior art, mutual interference when a plurality of sensors are close to each other is effectively avoided, in addition, synchronous signals of the master device and the slave device are PWM signals, the maximum frequency is 40 KHz, the timer interruption time is 2 microseconds, and the accuracy and effectiveness of receiving ADC sampling are ensured (when an on-chip ADC is used for sampling receiving, the PWM frequency needs to be reduced, and the timer interruption time needs to be increased). The number of the slave devices can be flexibly increased according to actual requirements, and the expansibility and flexibility of the system are improved.

Description

Technical Field

[0001] The present application relates to the technical field of optical sensors, and in particular to an expandable cascade diffuse reflection laser sensor. Background Art

[0002] Photoelectric sensors are widely used in industrial automation, logistics, security and other fields, especially when it is necessary to detect the presence of a target object. With the development of technology, photoelectric sensors not only require high precision, high reliability and a long detection distance, but also need to have a compact design and flexible deployment capabilities. Especially in a small space, the dense arrangement of multiple sensors has become a common application scenario. However, when multiple sensors are used close to each other, electromagnetic interference, light interference and other problems lead to the risk of misoperation, which seriously affects the stability and reliability of the system.

[0003] In order to solve the above problems, existing photoelectric sensors usually use a variety of methods to reduce mutual interference. For example, by adding a protective cover or sunshade to the sensor, the interference of external light can be effectively blocked; another method is to adjust the installation position and angle of the sensor to keep a certain distance between them, thereby reducing mutual influence; in addition, the sensitivity of the sensor can be reduced or its working mode can be changed, such as using pulse modulation, to reduce the impact of ambient light. Although these methods can alleviate the problem to a certain extent, it is still difficult to completely solve the problem in the scenario of densely arranged multiple sensors in a small space.

[0004] Although the above methods can reduce the interference between sensors to a certain extent, there are still obvious shortcomings in the environment where multiple sensors are densely arranged in a small space. First, adding a protective cover or a sunshade will increase the size of the sensor, which is not conducive to installation in a small space; second, adjusting the installation position and angle will be limited by space, making it difficult to achieve the optimal layout; finally, reducing sensitivity or changing the working mode will affect the detection performance of the sensor and cannot meet the requirements of high precision and high reliability. Therefore, how to effectively avoid mutual interference in an environment where multiple sensors are densely arranged has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In order to reduce the situation where multiple sensors are densely arranged and effectively avoid mutual interference, the present application provides an expandable cascade diffuse reflection laser sensor.

[0006] The present application provides an expandable cascade diffuse reflection laser sensor that adopts the following technical solution: A diffuse reflection laser sensor with expandable cascade includes a master device and at least one slave device. The master device and the slave device communicate with each other through a synchronization signal and a voltage division sampling signal. The master device and the slave device control the working states of a transmitting end and a receiving end in a time-sharing manner according to the synchronization signal and the voltage value to avoid mutual interference when multiple sensors are used in close proximity.

[0007] By adopting the above technical solution, it is possible to effectively avoid the mutual interference problem when multiple sensors are used close together, ensuring that each sensor works independently within a specific time period, thereby improving the stability and reliability of the system. In addition, the design can also realize the detection of regional detection targets, increase the detection distance of the sensor, reduce the installation space required for the sensor, and simplify the installation process of the sensor.

[0008] Preferably, the synchronization signal between the master device and the slave device is a PWM signal, which is used to trigger external interrupts of the master device and the slave device, and the transmission and reception of the master device and the slave device are controlled by the synchronization signal.

[0009] By adopting the above technical solution and using the PWM signal as the synchronization signal between the master device and the slave device, the external interrupts of the master device and the slave device can be accurately controlled to ensure that the transmission and reception of the master device and the slave device are controlled by the synchronization signal. This not only realizes the coordinated work between multiple sensors, effectively avoids the mutual interference problem caused by the close use of multiple sensors, but also improves the stability and reliability of the system.

[0010] Preferably, the maximum frequency of the synchronization signal is 40KHz, and the timer interrupt time is 2μs, which ensures the accuracy and effectiveness of the receiving ADC sampling (when using the on-chip ADC to sample the reception, the PWM frequency should be reduced and the timer interrupt time should be increased).

[0011] By adopting the above technical solution, the time accuracy of the master and slave devices when processing synchronization signals and executing timer interrupts can be ensured, thereby ensuring the effectiveness of the detection distance. Specifically, the maximum frequency of the synchronization signal is 40KHz, so that there is enough time in each cycle to complete the emission control, turn on the timer interrupt, ADC receive sampling and turn off the timer interrupt, avoiding the problem of insufficient time caused by the high frequency of the synchronization signal. The timer interrupt timing time is 2μs, ensuring that when the emission control is turned on, there is enough time to complete the receiving ADC sampling, thereby accurately capturing the returned optical signal and improving the reliability and accuracy of the detection.

[0012] Preferably, the number of slave devices can be increased according to actual needs.

[0013] By adopting the above technical solution, when multiple sensors are needed, the number of slave devices can be flexibly increased according to actual needs without redesigning or adjusting the structure of the entire system, thereby improving the scalability and flexibility of the system. At the same time, the synchronization signal and voltage division sampling signal between the master device and the slave device ensure the orderly operation of each sensor, avoid mutual interference when multiple sensors are used close together, and ensure the stability and reliability of the system.

[0014] Preferably, the transmitting end comprises a red laser diode with a main wavelength of 650nm, a plano-convex lens, a straight lens and a red filter, wherein the light emitted by the laser diode passes through the plano-convex lens, the straight lens and the red filter in sequence to form a straight laser spot.

[0015] By adopting the above technical solution, the combination of a red laser diode with a main wavelength of 650nm, a plano-convex lens, a straight lens and a red filter can effectively improve the brightness and clarity of the laser spot, expand the detection range and increase the detection distance.

[0016] Preferably, the receiving end comprises a red filter, a plano-convex lens and a photodiode, wherein the light reflected by the detection target is sequentially focused by the red filter and the plano-convex lens and then received by the photodiode.

[0017] By adopting the above technical solution, stray light of non-target wavelengths can be effectively filtered out, the signal-to-noise ratio can be improved, and the optical signal received by the photodiode can be made purer, thereby improving the detection accuracy and reliability. At the same time, the focusing effect of the plano-convex lens can concentrate the reflected light onto the photosensitive surface of the photodiode, further enhancing the intensity of the optical signal and extending the detection distance.

[0018] Preferably, the photodiode has a low dark current and a large light response value to improve detection sensitivity.

[0019] By adopting the above technical solution, the photodiode has a low dark current and a large light response value, which can significantly improve the detection sensitivity of the sensor and accurately detect the presence of the target even when the reflected light is weak, thereby improving the reliability and stability of the entire system.

[0020] Preferably, the sensor head and the amplifier are separately arranged, the sensor transmission and reception are on the same side, and the sensor head and the amplifier are connected by four wires, namely a power line, a ground line, a transmission control line and a reception sampling line.

[0021] By adopting the above technical solution, the sensor head and amplifier are separated. The sensor transmits and receives on the same side. The sensor head and the amplifier are connected by only four wires, namely the power line, the ground line, the transmission control line and the receiving sampling line. This not only significantly reduces the size of the sensor head, making it more compact and convenient for installation in a small space, but also simplifies the installation process and improves the installation efficiency. In addition, the design of the separation setting also helps to reduce the electromagnetic interference inside the sensor and improve the stability and reliability of the sensor.

[0022] Preferably, the sensor head also includes a pure hardware control circuit for LED display, which controls the on and off of the LED according to the strength of the photoelectric signal through a comparator to reduce the number of connections between the sensor head and the amplifier.

[0023] By adopting the above technical solution, the number of connections between the sensor head and the amplifier is significantly reduced, thereby effectively reducing the overall size of the sensor and improving the convenience of installation. At the same time, the comparator controls the brightness of the LED according to the strength of the photoelectric signal, which can intuitively reflect the current detection status and enhance the practicality and user experience of the sensor.

[0024] Preferably, the emission angle of the straight lens determines the width of the detection spot area to achieve detection of area-type detection targets.

[0025] By adopting the above technical solution, effective detection of regional detection targets can be achieved. Specifically, the emission angle of the straight lens determines the width of the detection spot area, allowing the sensor to evenly distribute the spot within a certain range, thereby covering a larger detection area. This not only improves the reliability and accuracy of detection, but also expands the application range of the sensor, making it suitable for occasions where a larger area of ​​target needs to be detected.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: 1. The master and slave devices communicate through synchronization signals and voltage division sampling signals. The master and slave devices control the working states of the transmitter and receiver in a time-sharing manner according to the synchronization signals and voltage values, thus avoiding mutual interference between multiple sensors when they are used close together and improving the stability and reliability of the system. 2. The use of a red laser diode with a main wavelength of 650nm and a specific optical system increases the detection distance, makes the detection spot clearly visible, and improves the detection accuracy and reliability; 3. The sensor head and amplifier are set separately, and the sensor transmission and reception are on the same side. The volume of the sensor head is greatly reduced, which is convenient for installation in a small space and simplifies the installation process of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic block diagram showing the principle of cascading master and slave devices in Example 1 of the present application.

[0028] Figure 2 This is a flowchart of the master-slave device cascading program in Example 1 of the present application.

[0029] Figure 3 This is a circuit block diagram of the sensor head in Example 1 of the present application.

[0030] Figure 4 It is a schematic diagram of the optical path of the sensor head in Example 1 of the present application. DETAILED DESCRIPTION

[0031] The following will be combined with the attached Figure 1-Figure 4 , a clear and complete description of the technical solutions in the embodiments of the present invention is given. The described embodiments are only possible technical implementations of the present invention, and not all implementations are possible. Those skilled in the art can fully combine the embodiments of the present invention to obtain other embodiments without creative work, and these embodiments are also within the scope of protection of the present invention. The inventors of the present application found that when multiple photoelectric sensors are used close to each other, they are easily interfered with each other, causing misoperation of the sensors. To this end, the present application mainly adopts the following design of an expandable cascade diffuse reflection laser sensor, which avoids mutual interference when multiple sensors are used close to each other, increases the detection distance, and simplifies the installation of the sensor. The following is a further detailed description of the present application.

[0032] Embodiment 1: Reference Figure 1 and Figure 2 An expandable cascade diffuse reflection laser sensor provided in an embodiment of the present application includes a master device and at least one slave device. The master device and the slave device communicate with each other through synchronization signals and voltage division sampling signals. The master device and the slave device control the working states of the transmitting end and the receiving end in a time-sharing manner according to the synchronization signals and the voltage values ​​to avoid mutual interference when multiple sensors are used close to each other.

[0033] Specifically, the main device includes a synchronization signal generator, a voltage division sampling module, an external interrupt controller, a timer interrupt controller and a transmission control module. The synchronization signal generator is used to generate a synchronization signal (such as a PWM signal), the voltage division sampling module is used to collect voltage values, the external interrupt controller is used to trigger an external interrupt and perform transmission control according to the interrupt count and the sampled voltage, the timer interrupt controller is used to control the receiving ADC sampling time, and the transmission control module is used to control the start, stop and power control of the transmitting end.

[0034] The synchronization signal generator can be implemented by a microprocessor or an application-specific integrated circuit (ASIC), the voltage division sampling module can be implemented by a resistor voltage division network, the external interrupt controller and the timer interrupt controller can be implemented by the functional module inside the microprocessor, and the transmission control module can be implemented by a transistor and an operational amplifier.

[0035] Specifically, the slave device includes a synchronization signal receiver, a voltage division sampling module, an external interrupt controller, a timer interrupt controller, a transmission control module and a reception control module. The synchronization signal receiver is used to receive the synchronization signal, the voltage division sampling module is used to collect the voltage value and perform transmission control according to the sampled voltage, the timer interrupt controller is used to control the receiving ADC sampling time, the transmission control module is used to control the opening, closing and power control of the transmitting end, and the reception control module is used to perform IV conversion on the photoelectric signal and amplify the converted signal.

[0036] The synchronization signal receiver can be implemented by a microprocessor or an application-specific integrated circuit (ASIC), the voltage division sampling module can be implemented by a resistor voltage division network, and the external interrupt controller and the timer interrupt controller can be implemented by the functional module inside the microprocessor. The transmission control module can be implemented by a transistor and an operational amplifier, and the receiving control module can be implemented by a photodiode and an operational amplifier.

[0037] The synchronization signal between the master device and the slave device is a PWM signal, which is used to trigger the external interrupt of the master device and the slave device. The transmission and reception of the master device and the slave device are controlled by the synchronization signal. The maximum frequency of the PWM signal is 40KHz, and the timer interrupt time is 2μs, which ensures the accuracy and effectiveness of the receiving ADC sampling (when using the on-chip ADC to sample the reception, the PWM frequency should be reduced and the timer interrupt time should be increased).

[0038] The number of slave devices can be increased according to actual needs, and can be increased to a maximum of 15 slave devices.

[0039] Reference Figure 3 and Figure 4 The transmitting end includes a red laser diode with a main wavelength of 650nm, a plano-convex lens, a straight lens and a red filter, wherein the light emitted by the laser diode passes through the plano-convex lens, the straight lens and the red filter in sequence to form a straight laser spot. The laser diode can be implemented by a semiconductor laser, the plano-convex lens can be made of glass or plastic material, the straight lens can be implemented by a cylindrical lens, and the red filter can be implemented by a coated filter.

[0040] The receiving end includes a red filter, a plano-convex lens and a photodiode, wherein the light reflected by the detection target is focused by the red filter and the plano-convex lens in turn and then received by the photodiode. The photodiode has a low dark current and a large light response value to improve the detection sensitivity. The photodiode can be implemented by a silicon-based photodiode, the red filter can be implemented by a coated filter, and the plano-convex lens can be made of glass or plastic material.

[0041] The sensor head and the amplifier are set separately, the sensor transmission and reception are on the same side, and the sensor head and the amplifier are connected by four wires, namely the power line, the ground line, the transmission control line and the reception sampling line. The sensor head also includes a pure hardware control circuit for LED display, which controls the LED on and off according to the strength of the photoelectric signal through a comparator to reduce the number of connections between the sensor head and the amplifier. The pure hardware control circuit for LED display can be implemented using a comparator and a resistor voltage divider network.

[0042] The emission angle of the straight lens determines the width of the detection spot area to achieve the detection of regional detection targets. The emission angle of the straight lens can be adjusted according to actual needs to adapt to different detection requirements.

[0043] The implementation principle of this embodiment is: through the synchronization signal and voltage division sampling signal between the master device and the slave device to communicate, the cascade and time-sharing control of multiple sensors are realized, and the mutual interference when multiple sensors are used close together is avoided. At the same time, by adopting a red laser diode with a main wavelength of 650nm and a corresponding optical system, the detection distance and the clarity of the detection spot are improved. The sensor head and the amplifier are set separately, which greatly reduces the volume of the sensor head and is convenient for installation in a small space. The LED display pure hardware control circuit reduces the number of connections between the sensor head and the amplifier, further reducing the volume of the sensor. By adjusting the emission angle of the straight lens, the detection of regional detection targets can be achieved. In summary, this embodiment provides an efficient, reliable and expandable cascade diffuse reflection laser sensor design solution, which solves the problem of mutual interference when multiple sensors are used close together, improves the detection distance and detection accuracy, and simplifies the installation and maintenance of the sensor.

[0044] Embodiment 2: The difference between this embodiment and the above-mentioned embodiments is that this embodiment focuses on the specific implementation method of the separate arrangement of the sensor head and the amplifier, and the detailed design of the pure hardware control circuit of the LED display.

[0045] Specifically, the sensor head includes a laser diode, a plano-convex lens, a straight lens, a red filter and a photodiode. These components ensure the accuracy and stability of the optical path through precise optical design and mechanical fixation. The housing of the sensor head is made of aluminum alloy material, which has good heat dissipation and impact resistance. The interface part of the sensor head adopts a standard connector, which is convenient for quick connection and removal with the amplifier.

[0046] The amplifier includes a signal processing module, a power management module, a transmission control module and a reception control module. The signal processing module is used to amplify and filter the received optical signal, the power management module is used to provide a stable power supply, the transmission control module is used to control the transmission of the laser diode, and the reception control module is used to control the reception of the photodiode. The signal processing module can be implemented by an operational amplifier and a filter, the power management module can be implemented by a voltage regulator and a battery management system, and the transmission control module and the reception control module can be implemented by a transistor switch or a relay.

[0047] The pure hardware control circuit of LED display includes a comparator, a resistor voltage divider network and an LED. The comparator is used to compare the strength of the photoelectric signal, the resistor voltage divider network is used to provide a reference voltage, and the LED is used to display the detection result. The comparator can be implemented with a high-speed comparator, the resistor voltage divider network can be implemented with a precision resistor, and the LED can be implemented with a high-brightness LED. By controlling the LED on and off according to the strength of the photoelectric signal through the comparator, the detection result of the sensor can be displayed in real time without relying on an external control circuit.

[0048] The implementation principle of this embodiment is: through the separate design of the sensor head and the amplifier, the miniaturization and portability of the sensor head are achieved, while the complex functional modules of the amplifier are retained, ensuring the high performance and high reliability of the sensor. The LED display pure hardware control circuit reduces the number of connections between the sensor head and the amplifier, further simplifying the installation and maintenance of the sensor. Through precise optical design and mechanical fixation, the accuracy and stability of the optical path are ensured, and the detection distance and detection accuracy are improved. In summary, this embodiment provides an efficient, reliable, scalable cascade diffuse reflection laser sensor design solution, which solves the problem of mutual interference when multiple sensors are used close together, improves the detection distance and detection accuracy, and simplifies the installation and maintenance of the sensor.

[0049] Embodiment 3: The difference between this embodiment and the above-mentioned embodiments is that this embodiment focuses on the optimized design of the optical system to further improve the detection distance and the clarity of the detection spot.

[0050] Specifically, the optical system of the transmitting end includes a laser diode, a plano-convex lens, a straight lens, and a red filter. In order to further improve the detection distance and the clarity of the detection spot, these components can be optimized. For example, the plano-convex lens can choose a material with a high refractive index to improve the light convergence effect; the straight lens can choose a high-precision cylindrical lens to accurately control the shape and width of the light spot; the red filter can choose a high-transmittance coated filter to reduce light loss.

[0051] The optical system at the receiving end includes a red filter, a plano-convex lens, and a photodiode. In order to further improve the detection sensitivity, these components can be optimized. For example, the red filter can choose a high-transmittance coated filter to reduce light loss; the plano-convex lens can choose a high-refractive-index material to improve the focusing effect of light; the photodiode can choose a model with low dark current and large light response value to improve the detection sensitivity.

[0052] Specifically, laser diodes can use higher-power semiconductor lasers to increase light intensity; plano-convex lenses can choose glass materials with high refractive index to improve light convergence effects; straight lenses can choose high-precision cylindrical lenses to accurately control the shape and width of the light spot; red filters can choose high-transmittance coated filters to reduce light loss. Photodiodes can choose models with low dark current and large light response values ​​to improve detection sensitivity.

[0053] The implementation principle of this embodiment is: through the optimization design of the optical system, the detection distance and the clarity of the detection spot are further improved. The high-refractive-index plano-convex lens and the high-precision one-way lens enhance the light convergence effect, the high-transmittance red filter reduces the light loss, and the high-sensitivity photodiode improves the detection sensitivity. In summary, this embodiment provides an efficient optical system optimization design, further improves the performance of the diffuse reflection laser sensor, and makes it show higher reliability and accuracy in a variety of application scenarios.

[0054] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A cascaded diffuse reflection laser sensor, characterized in that: The invention comprises a master device and at least one slave device, wherein the master device and the slave device communicate with each other through synchronization signals and voltage division sampling signals, and the master device and the slave device control the working states of the transmitting end and the receiving end in time-sharing according to the synchronization signals and the voltage values, so as to reduce mutual interference when multiple sensors are used close to each other.

2. The expandable cascade diffuse reflection laser sensor according to claim 1, characterized in that: The synchronization signal between the master device and the slave device is a PWM signal, which is used to trigger external interrupts of the master device and the slave device. The transmission and reception of the master device and the slave device are both controlled by the synchronization signal.

3. The expandable cascade diffuse reflection laser sensor according to claim 2, characterized in that: The maximum frequency of the synchronization signal is 40KHz, and the timer interrupt time is 2μs, which ensures the accuracy and effectiveness of the receiving ADC sampling (when using the on-chip ADC to sample the reception, the PWM frequency should be reduced and the timer interrupt time should be increased).

4. The expandable cascade diffuse reflection laser sensor according to claim 1, characterized in that: The number of the slave devices can be increased according to actual needs.

5. The expandable cascade diffuse reflection laser sensor according to claim 1, characterized in that: The transmitting end comprises a red laser diode with a main wavelength of 650nm, a plano-convex lens, a straight lens and a red filter, wherein the light emitted by the laser diode passes through the plano-convex lens, the straight lens and the red filter in sequence to form a straight laser spot.

6. The expandable cascade diffuse reflection laser sensor according to claim 1, characterized in that: The receiving end comprises a red filter, a plano-convex lens and a photodiode, wherein the light reflected by the detection target is sequentially focused by the red filter and the plano-convex lens and then received by the photodiode.

7. The expandable cascade diffuse reflection laser sensor according to claim 5, characterized in that: The photodiode has low dark current and large light response value to improve detection sensitivity.

8. The expandable cascade diffuse reflection laser sensor according to claim 1, characterized in that: The sensor head and the amplifier are separately arranged, the sensor transmission and reception are on the same side, and the sensor head and the amplifier are connected by four wires, namely a power line, a ground line, a transmission control line and a reception sampling line.

9. The expandable cascade diffuse reflection laser sensor according to claim 8, characterized in that: The sensor head also includes a pure hardware control circuit for LED display, which controls the on and off of the LED according to the strength of the photoelectric signal through a comparator to reduce the number of connections between the sensor head and the amplifier.

10. The expandable cascade diffuse reflection laser sensor according to claim 1, characterized in that: The emission angle of the straight lens determines the width of the detection spot area to achieve the detection of regional detection targets.

Images