Background Suppression Photoelectric Sensor and Black-White Difference Adjustment Method

Abstract

The present application discloses a background suppression photoelectric sensor and a black-and-white difference adjustment method. In this background suppression photoelectric sensor, the transmitting lens is configured to minimize the spot diameter of the transmitted optical signal after passing through the transmitting lens at a first detection distance; the receiving lens is configured such that when the target black object is at a second detection distance, the waveform of the detection electrical signal generated by the optical receiving circuit exhibits an odd-symmetric characteristic, and when the target white object is at the first detection distance, the waveform of the detection electrical signal generated by the optical receiving circuit exhibits an odd-symmetric characteristic; the ratio of the difference between the first detection distance and the second detection distance to the first detection distance is the black-and-white difference. The present application adjusts the black-and-white difference of the sensor according to the detection distances of the background suppression photoelectric sensor for the target black object and the target white object, and can make the black-and-white difference of the background suppression photoelectric sensor of the double photodiode type not exceed 5%, solving the problem of the relatively large black-and-white difference of the traditional double photodiode type background suppression photoelectric sensor.

Description

Technical Field

[0001] This application relates to the technical field of sensors, and particularly to a background suppression photoelectric sensor and a black-and-white difference adjustment method. Background Art

[0002] The background suppression photoelectric sensor distinguishes the effective signal from the background interference by setting a specific detection distance, thereby improving the detection accuracy in a complex environment, and is applicable to application scenarios where it is necessary to avoid misjudgment of strong reflected light or complex background interference.

[0003] However, the traditional dual-photodiode type background suppression photoelectric sensor usually has a large black-and-white difference, and its black-and-white difference is about 10% - 30%. This means that this type of sensor is prone to misjudgment in a high-reflection background or complex environment, which greatly limits its application scenarios. Although the laser type background suppression photoelectric sensor can have higher precision and a smaller black-and-white difference, and its black-and-white difference is generally less than 5%, its cost is much higher than that of the dual-photodiode type background suppression photoelectric sensor, and the extremely high cost also limits the application of the laser type background suppression photoelectric sensor. Summary of the Invention

[0004] In view of the above technical problems, this application provides a background suppression photoelectric sensor and a black-and-white difference adjustment method, so that the black-and-white difference of the dual-photodiode type background suppression photoelectric sensor can not exceed 5%, thereby solving the above technical problems.

[0005] In a first aspect, this application provides a background suppression photoelectric sensor, including:

[0006] A light emission module, which includes a light source, a light emission circuit, and an emission lens. The light emission circuit is used to drive the light source to generate an emission light signal, and the emission lens is used to focus the emission light signal in the target direction;

[0007] A light reception module, which includes a reception lens, a dual photodiode, and a light reception circuit. The reception lens is used to focus the received light signal reflected from the target direction onto the dual photodiode. The dual photodiode is used to convert the received light signal into two electrical signals, and the light reception circuit is used to convert the two electrical signals into a detection electrical signal;

[0008] A main control module, which is used to compare the detection electrical signal with a preset detection threshold to determine whether there is an object in the target direction;

[0009] Wherein, the emission lens is configured to: make the spot diameter of the emission light signal after passing through the emission lens the smallest at the first detection distance;

[0010] The receiving lens is configured such that when the target black object is at the second detection distance, the waveform of the detection electrical signal generated by the light receiving circuit exhibits an odd symmetry characteristic, and when the target white object is at the first detection distance, the waveform of the detection electrical signal generated by the light receiving circuit exhibits an odd symmetry characteristic;

[0011] The first detection distance and the second detection distance satisfy that the ratio of the difference between the first detection distance and the second detection distance to the first detection distance is the black-and-white difference of the background suppression photoelectric sensor.

[0012] In a second aspect, the present application provides a method for adjusting the black-and-white difference of a background suppression photoelectric sensor, which is applied to the background suppression photoelectric sensor as described in the first aspect. The method for adjusting the black-and-white difference of the background suppression photoelectric sensor includes:

[0013] Preset the first detection distance as the equilibrium position of the target white object, determine the equilibrium position of the target black object according to the first detection distance and the preset black-and-white difference, and set the equilibrium position of the target black object as the second detection distance. The equilibrium position is the distance corresponding to when the waveform of the detection circuit generated by the light receiving circuit of the background suppression photoelectric sensor exhibits an odd symmetry characteristic;

[0014] Adjust the position of the receiving lens of the background suppression photoelectric sensor so that when the target black object is at the second detection distance, the waveform of the detection electrical signal generated by the light receiving circuit exhibits an odd symmetry characteristic, and when the target white object is at the first detection distance, the waveform of the detection electrical signal generated by the light receiving circuit exhibits an odd symmetry characteristic.

[0015] The background suppression photoelectric sensor and the method for adjusting the black-and-white difference provided by the present application. The method for adjusting the black-and-white difference of the background suppression photoelectric sensor presets the first detection distance as the equilibrium position of the target white object, calculates the equilibrium position of the target black object as the second detection distance based on the preset black-and-white difference, and at the same time dynamically adjusts the position of the receiving lens so that the detection electrical signal waveforms of the two objects exhibit odd symmetry characteristics at the corresponding distances. At this time, the actual black-and-white difference of the background suppression sensor is the preset black-and-white difference. The present application adjusts the black-and-white difference of the sensor according to the detection distances of the target black object and the target white object by the sensor, and can make the black-and-white difference of the dual-photodiode type background suppression photoelectric sensor not exceed 5%, solving the problem of the large black-and-white difference of the traditional dual-photodiode type background suppression photoelectric sensor.

[0016] These aspects or other aspects of the present application will be more clearly understood in the following description of the embodiments. Description of the Drawings

[0017] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0018] Figure 1 The schematic diagram of the background suppression photoelectric sensor provided by the embodiment of the present application is shown.

[0019] Figure 2 Another module schematic diagram of the background suppression photoelectric sensor provided by the embodiment of the present application is shown.

[0020] Figure 3 The electrical signal waveform diagram of the light receiving circuit of the background suppression photoelectric sensor provided by the embodiment of the present application is shown.

[0021] Figure 4 The flowchart of the black and white difference adjustment method of the background suppression photoelectric sensor provided by the embodiment of the present application is shown.

[0022] Figure 5 Another flowchart of the black and white difference adjustment method of the background suppression photoelectric sensor provided by the embodiment of the present application is shown.

[0023] Figure 6 Another flowchart of the black and white difference adjustment method of the background suppression photoelectric sensor provided by the embodiment of the present application is shown.

[0024] Figure 7 Another flowchart of the black and white difference adjustment method of the background suppression photoelectric sensor provided by the embodiment of the present application is shown.

[0025] Figure 8 Another flowchart of the black and white difference adjustment method of the background suppression photoelectric sensor provided by the embodiment of the present application is shown.

[0026] Figure 9 Another flowchart of the black and white difference adjustment method of the background suppression photoelectric sensor provided by the embodiment of the present application is shown. Detailed implementation manners

[0027] In order to enable those skilled in the art to better understand the solutions of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present application.

[0028] In the embodiments of the present application, it should be noted that, in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0029] It should be noted that, in the embodiments of the present application, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / ", unless otherwise specified, generally represents an "or" relationship between the preceding and following associated objects.

[0030] The embodiments of the present application provide a background suppression photoelectric sensor. Figure 1 The schematic diagram of the background suppression photoelectric sensor provided by the embodiments of the present application is shown, as Figure 1 shown, the background suppression photoelectric sensor includes a light emission module 100, a light reception module 200, and a main control module 300.

[0031] The light emission module 100 specifically includes a light source 110, a light emission circuit 120, and an emission lens 130. The light emission circuit 120 is used to drive the light source 110 to generate an emission light signal, and the emission lens 130 is used to focus the emission light signal to the target direction X (direction). If there is a target object 400 in the target direction (X direction), the target object will reflect the emission light signal back.

[0032] The light reception module 200 specifically includes a reception lens 210, a dual photodiode 220, and a light reception circuit 230. The reception lens 210 is used to focus the received light signal reflected from the target direction (X direction) to the dual photodiode 220. The dual photodiode 220 is used to convert the received light signal into two electrical signals, and the light reception circuit 230 is used to convert the two electrical signals into a detection electrical signal. Specifically, the dual photodiode is integrated by a photodiode PD1 and a photodiode PD2. After the received light signal reflected from the target direction (X direction) passes through the reception lens 210, both the photodiode PD1 and the photodiode PD2 are partially covered with the light signal. Therefore, the photodiode PD1 and the photodiode PD2 respectively convert the light signals on them into electrical signals, and these two electrical signals are processed by the light reception circuit 230 to finally obtain the detection electrical signal. The detection electrical signal is the electrical signal required for the background suppression photoelectric sensor to determine whether there is a target object in the target direction.

[0033] The main control module 300 is configured to compare the detected electrical signal with a preset detection threshold to determine whether there is an object in the target direction. Optionally, the main control module 300 is a chip with processing functions, such as a microcontroller unit, an analog integrated circuit, etc. The main control module is configured to convert the detected electrical signal in analog form into a digital signal, and then compare it with the preset detection threshold inside to determine whether there is an object in the target direction. For example, when the detected electrical signal is greater than the detection threshold, it is considered that there is an object in the target direction.

[0034] Wherein, the transmitting lens 130 is configured to: make the spot diameter of the transmitted optical signal after passing through the transmitting lens the smallest at the first detection distance, so that the spot of the transmitted optical signal at the first detection distance is the clearest. The receiving lens is configured to: when there is a target black object at the second detection distance, the waveform of the detected electrical signal generated by the optical receiving circuit presents an odd symmetry characteristic, and when there is a target white object at the first detection distance, the waveform of the detected electrical signal generated by the optical receiving circuit presents an odd symmetry characteristic. The first detection distance and the second detection distance satisfy: the ratio of the difference between the first detection distance and the second detection distance to the first detection distance is the black-and-white difference of the background suppression photoelectric sensor.

[0035] In the embodiment of the present application, by adjusting the positions of the transmitting lens and the receiving lens, it is realized that when there is a target black object at the second detection distance, the waveform of the detected electrical signal corresponding thereto presents an odd symmetry characteristic, and when there is a target white object at the first detection distance, the waveform of the detected electrical signal corresponding thereto presents an odd symmetry characteristic. That is, at this time, the second detection distance and the first detection distance are respectively the limit distances for the sensor to detect the target black object and the target white object. Therefore, as long as the ratio of the difference between the first detection distance and the second detection distance to the first detection distance is controlled, the black-and-white difference of the background suppression photoelectric sensor can be controlled. For example, if the black-and-white difference of the background suppression photoelectric sensor is required to be 5%, then only need to adjust the position of the receiving lens so that the ratio of the difference between the first detection distance and the second detection distance to the first detection distance is 5%.

[0036] Further, in the actual application of the background suppression photoelectric sensor, it may be necessary to adjust the position of the receiving lens to modify its detection distance, which will destroy the distances corresponding to the waveforms of the detected electrical signals presenting symmetric characteristics corresponding to the target white object and the target black object. However, for the background suppression photoelectric sensor provided in the embodiment of the present application, after its black-and-white difference is adjusted, if the receiving lens is adjusted at this time to reduce the detection distance of the sensor, because the reflection energy of the white object is stronger than that of the black object, when the detection distance of the sensor decreases, the difference between the distance corresponding to the waveform of the detected electrical signal presenting symmetric characteristics corresponding to the target white object and the first detection distance will be greater than the difference between the distance corresponding to the waveform of the detected electrical signal presenting symmetric characteristics corresponding to the target black object and the second detection distance. This shows that when the detection distance of the sensor decreases, the black-and-white difference of the sensor will further decrease.

[0037] It can be seen from this that the background suppression photoelectric sensor provided by the embodiments of the present application can achieve that the black-and-white difference of the dual-photodiode type background suppression photoelectric sensor does not exceed 5%, solving the problem of the large black-and-white difference of the traditional dual-photodiode type background suppression photoelectric sensor.

[0038] It should be clear that the purpose of the embodiments of the present application is to adjust the black-and-white difference of the dual-photodiode type background suppression photoelectric sensor not to exceed 5%. Moreover, when the embodiments of the present application adjust the black-and-white difference, only the lens position needs to be adjusted. Therefore, it is not necessary to modify the circuit part of the background suppression photoelectric sensor. Therefore, in the embodiments of the present application, the light receiving circuit and the light emitting circuit can both be implemented by known technologies, and the corresponding circuit structures will not be elaborated too much herein.

[0039] In some embodiments, in the background suppression photoelectric sensor provided by the embodiments of the present application, the main control module 300 is configured to:

[0040] Set the waveform amplitude difference between the waveform of the second detection electrical signal and the waveform of the first detection electrical signal as the critical detection threshold range. The critical detection threshold is used to determine whether the waveform amplitude of the detection electrical signal generated by the light receiving circuit 230 is within the critical detection threshold range when the waveform of the detection electrical signal generated by the light receiving circuit presents an odd symmetry feature.

[0041] If the judgment result is yes, output the result that there is an object in the target direction.

[0042] If the judgment result is no, output the result that there is no object in the target direction.

[0043] The second detection electrical signal is: the detection electrical signal generated by the light receiving circuit 230 when the target black object is at the second detection distance.

[0044] The first detection electrical signal is: the detection electrical signal generated by the light receiving circuit 230 when the target white object is at the first detection distance.

[0045] When the target object is within the detection distance of the background suppression photoelectric sensor, it can be clearly determined whether there is a target object in the target direction by comparing the detected electrical signal with a preset detection threshold. However, when the target object is at the critical position of the detection distance of the background suppression photoelectric sensor, the waveform of the detected electrical signal corresponding to the target object presents an odd symmetry characteristic at this time. According to the detected electrical signal and the preset detection threshold, the sensor may not be able to output the correct result. In view of this, after adjusting the black and white difference of the background suppression photoelectric sensor provided in the embodiment of the present application, the waveform assignment of the detected electrical signal corresponding to the target black object and the waveform assignment of the detected electrical signal corresponding to the target black object are also used as the critical detection threshold, thereby improving the detection accuracy of the background suppression photoelectric sensor at the critical position of the detection distance.

[0046] In some embodiments, Figure 2 shows another module schematic diagram of the background suppression photoelectric sensor provided in the embodiment of the present application. As Figure 2 shown, in the background suppression photoelectric sensor provided in the embodiment of the present application, the light receiving circuit 230 includes:

[0047] A differential amplification unit 231 for performing differential amplification processing on two electrical signals to generate a first electrical signal.

[0048] A differential unit 232 for performing differential processing on the first electrical signal to generate a second electrical signal.

[0049] An inverting amplification unit 233 for performing inverting amplification processing on the second electrical signal to generate a detected electrical signal.

[0050] For the background suppression photoelectric sensor provided in the embodiment of the present application, the light receiving circuit 230 sequentially performs differential amplification processing, differential processing, and inverting amplification processing on the two optical signals generated by the double photodiode 220, so as to obtain a detected electrical signal for determining whether there is a target object in the target direction. Optionally, Figure 3 shows the electrical signal waveform diagram of the light receiving circuit of the background suppression photoelectric sensor provided in the embodiment of the present application. As Figure 3As shown, it represents the electrical signal waveform diagram of the light receiving circuit when there is a detected object in the target direction. At this time, the electrical signal energy output by the photodiode PD1 is greater than that output by the photodiode PD2. After passing through the differential amplification unit 231, their waveforms are both downward waveforms. After passing through the differentiation unit again, the waveform becomes two parts, up and down. At this time, the downward waveform is much larger than the upward waveform. And finally, after passing through the direction amplification unit, the upward waveform will be much larger than the downward waveform. That is, in the embodiment of the present application, the main control module can judge whether there is an object in the target direction by judging the waveform of the detection electrical signal output by the reverse amplification unit 233. It can be understood that when the object is at the critical position of the detection distance, the waveform of the detection electrical signal will exhibit an odd symmetry characteristic, that is, the upward waveform is the same as the downward waveform, and the amplitude of the waveform is determined by the reflection ability of the object.

[0051] It should be clear that the corresponding circuit structures of the differential amplification unit, differentiation unit, and reverse amplification unit that can achieve the above functions can all be realized by existing circuit principles, and the purpose of the embodiment of the present application is not to innovate in this direction. Therefore, the circuit structures of the above differential amplification unit, differentiation unit, and reverse amplification unit are not described in detail here.

[0052] The background suppression photoelectric sensor provided by the embodiment of the present application presets the first detection distance as the equilibrium position of the target white object by adjusting the position of the transmitting lens, and calculates the equilibrium position of the target black object as the second detection distance based on the preset black and white difference. At the same time, by dynamically adjusting the position of the receiving lens, the detection electrical signal waveforms of the two objects at the corresponding distances exhibit an odd symmetry characteristic. At this time, the actual black and white difference of the background suppression sensor is the ratio of the difference between the first detection distance and the second detection distance to the first detection distance. The embodiment of the present application adjusts the black and white difference of the sensor according to the detection distances of the target black object and the target white object, and can make the black and white difference of the background suppression photoelectric sensor of the double photodiode type not exceed 5%, solving the problem of the large black and white difference of the traditional double photodiode type background suppression photoelectric sensor.

[0053] The embodiment of the present application also provides a method for adjusting the black and white difference of a background suppression photoelectric sensor, which is applied to the background suppression photoelectric sensor as described in the above embodiment. Figure 4 The flowchart of the method for adjusting the black and white difference of the background suppression photoelectric sensor provided by the embodiment of the present application is shown. As Figure 4 shown, the method for adjusting the black and white difference of the background suppression photoelectric sensor includes:

[0054] Step S100: Preset the first detection distance as the equilibrium position of the target white object. Determine the equilibrium position of the target black object based on the first detection distance and the preset black-and-white difference, and set the equilibrium position of the target black object as the second detection distance. The black-and-white difference of the background suppression photoelectric sensor is determined by the equilibrium position of the target black object and the equilibrium position of the target white object. Therefore, after assuming the value of the black-and-white difference and the equilibrium position of the target white object, the equilibrium position of the target black object can be further obtained. The equilibrium position is the distance corresponding to when the waveform of the detection circuit generated by the light receiving circuit of the background suppression photoelectric sensor exhibits odd symmetry characteristics. Specifically, the equilibrium position is the distance between the target object and the sensor when the target object is at the critical position of the detection distance of the background suppression photoelectric sensor.

[0055] Step S200: Adjust the position of the receiving lens of the background suppression photoelectric sensor so that the waveform of the detection electrical signal generated by the light receiving circuit exhibits odd symmetry characteristics when the target black object is at the second detection distance, and the waveform of the detection electrical signal generated by the light receiving circuit exhibits odd symmetry characteristics when the target white object is at the first detection distance. At this time, the second detection distance and the first detection distance are respectively the limit distances for the background suppression photoelectric sensor to detect the target black object and the target white object. As long as the first detection distance and the second detection distance can be controlled, the black-and-white difference of the background suppression photoelectric sensor can be controlled. For example, if the black-and-white difference of the background suppression photoelectric sensor is required to be 5%, then only need to adjust the position of the receiving lens so that the black-and-white difference calculated based on the first detection distance and the second detection distance is 5%.

[0056] The method for adjusting the black-and-white difference of the background suppression photoelectric sensor provided by this application presets the first detection distance as the equilibrium position of the target white object, calculates the equilibrium position of the target black object as the second detection distance based on the preset black-and-white difference, and at the same time dynamically adjusts the position of the receiving lens so that the waveforms of the detection electrical signals of the two objects exhibit odd symmetry characteristics at the corresponding distances. At this time, the actual black-and-white difference of the background suppression sensor is the preset black-and-white difference. This application adjusts the black-and-white difference of the sensor according to the detection distances of the sensor for the target black object and the target white object, and can make the black-and-white difference of the background suppression photoelectric sensor of the double photodiode type not exceed 5%, solving the problem of the large black-and-white difference of the traditional double photodiode type background suppression photoelectric sensor.

[0057] In some embodiments, Figure 5 shows another flowchart of the method for adjusting the black-and-white difference of the background suppression photoelectric sensor provided by the embodiment of this application. As Figure 5 shown, step S100: The step of presetting the first detection distance as the equilibrium position of the target white object includes:

[0058] Step S110: Adjust the position of the emission lens of the background suppression photoelectric sensor until the spot imaging of the emitted optical signal focused by the emission lens reaches a preset clarity at a preset first distance.

[0059] Step S120: Select any position within a distance not exceeding the first distance from the emission lens and preset it as the first detection distance.

[0060] Preferably, in step S110, the optimal position of the first distance is the position where the human eye imaging is clearest. Therefore, at this time, the background suppression photoelectric sensor is more sensitive to optical signals, and the closer to the background suppression photoelectric sensor, the higher the sensitivity of the background suppression photoelectric sensor to optical signals. In step S120, the optimal position of the first detection distance is the first distance. Because in the process of step 200, the position of the receiving lens needs to be adjusted, and adjusting the position of the receiving lens may cause the detection distance of the background suppression photoelectric sensor to become smaller. Therefore, to ensure that the background suppression photoelectric sensor has a larger detection distance after adjusting the black and white difference, the first detection distance is preferably the first distance here.

[0061] In some embodiments, step S100: The step of determining the equilibrium position of the target black object according to the first detection distance and the preset black and white difference and setting the equilibrium position of the target black object as the second detection distance includes:

[0062] Obtain the equilibrium position of the target black object according to the black and white difference equation;

[0063] wherein, the black and white difference equation is:

[0064] .

[0065] In the actual application of the background suppression photoelectric sensor, the position of the receiving lens may need to be adjusted to modify its detection distance, which will destroy the symmetry of the waveforms of the detection electrical signals corresponding to the target white object and the target black object. However, for the background suppression photoelectric sensor provided in the embodiments of the present application, when the black and white difference is adjusted, if the receiving lens is adjusted at this time to reduce the detection distance of the sensor, then the black and white difference of the background suppression photoelectric sensor will also be further reduced at this time. This is because the reflection energy of the white object is stronger than that of the black object. Therefore, when the detection distance of the sensor decreases, the difference between the distance corresponding to the waveform of the detection electrical signal of the target white object presenting a symmetric feature and the first detection distance will be greater than the difference between the distance corresponding to the waveform of the detection electrical signal of the target black object presenting a symmetric feature and the second detection distance. It can be seen from this that when the detection distance of the sensor decreases, the black and white difference of the sensor will be further reduced.

[0066] In some embodiments, Figure 6 shows another flowchart of the black and white difference adjustment method of the background suppression photoelectric sensor provided by the embodiments of the present application, asFigure 6 As shown, the steps of adjusting the position of the receiving lens of the background suppression photoelectric sensor so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic, and so that the waveform of the detection electrical signal generated by the light receiving circuit when the target white object is at the first detection distance exhibits an odd symmetry characteristic, include:

[0067] Step S210: Adjust the position of the receiving lens of the background suppression photoelectric sensor so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic.

[0068] Step S220: Obtain the waveform of the detection electrical signal generated by the light receiving circuit when the target white object is at the first detection distance, and determine whether the waveform of the detection electrical signal generated by the light receiving circuit when the target white object is at the first detection distance exhibits an odd symmetry characteristic.

[0069] If the judgment result is yes, mark the positions of the transmitting lens and the receiving lens as positions having a preset black-and-white difference;

[0070] If the judgment result is no, return to execute the step: adjust the position of the receiving lens of the background suppression photoelectric sensor so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic until the judgment result is yes.

[0071] Optionally, after the position of the transmitting lens is determined, it is necessary to adjust the position of the receiving lens so that the waveforms of the corresponding detection electrical signals of the target black object and the target white object both exhibit odd symmetry characteristics at the balance position. Since the light reflection ability of the black object is weaker than that of the white object, in the embodiments of the present application, the position of the receiving lens is adjusted based on the target black object, that is, first make the waveform of the corresponding detection electrical signal of the target black object exhibit odd symmetry characteristics at the second detection distance, and then check whether the waveform of the corresponding detection electrical signal of the target white object exhibits odd symmetry characteristics at the first detection distance at this time. By repeatedly executing this process, a position of the receiving lens can finally be found so that the waveforms of the corresponding detection electrical signals of the target black object and the target white object both exhibit odd symmetry characteristics at the balance position. At this time, the black-and-white difference of the background suppression photoelectric sensor is:

[0072] .

[0073] In some embodiments, Figure 7 shows another flowchart of the method for adjusting the black-and-white difference of the background suppression photoelectric sensor provided by the embodiments of the present application, as Figure 7As shown, the steps of adjusting the position of the receiving lens of the background suppression photoelectric sensor so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic include:

[0074] Adjust the distance between the receiving lens and the dual photodiodes of the background suppression photoelectric sensor and / or adjust the distance between the receiving lens and the transmitting lens so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic.

[0075] Optionally, adjusting the distance between the receiving lens and the dual photodiodes of the background suppression photoelectric sensor will change the position of the light spot on the dual photodiodes, thereby affecting the detection sensitivity of the sensor. Adjusting the distance between the receiving lens and the transmitting lens will change the detection distance of the sensor. In the embodiments of the present application, by adjusting the position of the receiving lens in two orthogonal directions, the waveform of the detection electrical signal generated by the target black object at the second detection distance can exhibit an odd symmetry characteristic. For the background suppression photoelectric sensor, the relationship between the waveform characteristics of the detection electrical signal, the lens position, and the detection distance is non-linear. The non-linear system allows multiple lens position configurations to make the waveform of the detection electrical signal of the target black object at the second detection distance exhibit an odd symmetry characteristic, which means that by adjusting the position of the receiving lens in two orthogonal directions, there are multiple sets of solutions that can satisfy the condition that the waveform of the detection electrical signal corresponding to the target black object exhibits an odd symmetry. After obtaining multiple receiving lens positions for the target black object, it is possible to find a solution from these multiple receiving lens positions that makes the waveform of the detection electrical signal corresponding to the target white object at the first detection distance exhibit an odd symmetry characteristic. The black-and-white difference is an important characteristic inherent in the background suppression photoelectric sensor itself. Therefore, through experiments, it is certain to find a lens position from multiple receiving lens positions that satisfies the condition that the waveform of the detection electrical signal corresponding to the target white object at the first detection distance exhibits an odd symmetry characteristic.

[0076] In some embodiments, Figure 8 shows another flowchart of the black-and-white difference adjustment method for the background suppression photoelectric sensor provided by the embodiments of the present application, as Figure 8 shown. Step S200: After the step of adjusting the position of the receiving lens of the background suppression photoelectric sensor so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic and the waveform of the detection electrical signal generated by the light receiving circuit when the target white object is at the first detection distance exhibits an odd symmetry characteristic, further includes:

[0077] Step S300: Set the waveform amplitude difference between the waveform of the second detection electrical signal and the waveform of the first detection electrical signal as the critical detection threshold range. The critical detection threshold is used to determine whether the waveform amplitude of the detection electrical signal generated by the optical receiving circuit is within the critical detection threshold range when the waveform of the detection electrical signal generated by the optical receiving circuit exhibits an odd symmetry characteristic.

[0078] If the judgment result is yes, output the result that there is an object in the target direction of the background suppression photoelectric sensor.

[0079] If the judgment result is no, output the result that there is no object in the target direction of the background suppression photoelectric sensor.

[0080] The second detection electrical signal is: the detection electrical signal generated by the optical receiving circuit when the target black object is at the second detection distance;

[0081] The first detection electrical signal is: the detection electrical signal generated by the optical receiving circuit when the target white object is at the first detection distance.

[0082] When the object is within the detection distance of the background suppression photoelectric sensor, it can be clearly judged whether there is an object in the target direction according to the comparison between the detection electrical signal and the preset detection threshold. However, when the object is at the critical position of the detection distance of the background suppression photoelectric sensor, at this time, the waveform of the detection electrical signal corresponding to the object exhibits an odd symmetry characteristic, and the sensor may not be able to output the correct result based on the detection electrical signal and the preset detection threshold. In view of this, after adjusting the black-white difference of the background suppression photoelectric sensor provided in the embodiment of the present application, the waveform assignment of the detection electrical signal corresponding to the target black object and the waveform assignment of the detection electrical signal corresponding to the target black object are also used as the critical detection threshold, thereby improving the detection accuracy of the background suppression photoelectric sensor at the critical position of the detection distance.

[0083] In some embodiments, Figure 9 shows another flowchart of the black-white difference adjustment method of the background suppression photoelectric sensor provided in the embodiment of the present application. As Figure 9 shown, after the step S300 of setting the waveform difference between the waveform of the second detection electrical signal and the waveform of the first detection electrical signal as the critical detection threshold range, it further includes:

[0084] Step S400: Set the preset first hysteresis threshold and the preset second hysteresis threshold as the hysteresis of the two critical values of the critical detection threshold range respectively. The two critical values of the critical detection threshold range are the waveform amplitudes of the first detection electrical signal and the second detection electrical signal respectively.

[0085] The first hysteresis threshold and the second hysteresis threshold are used to determine whether the waveform amplitude of the detected electrical signal is between the first hysteresis threshold and the waveform amplitude of the first detected electrical signal, or between the second hysteresis threshold and the waveform amplitude of the second detected electrical signal, when the waveform of the detected electrical signal generated by the optical receiving circuit exhibits an odd-symmetric characteristic and then deviates from the critical detection threshold range.

[0086] If the judgment result is yes, then output the result that there is an object in the target direction of the background suppression photoelectric sensor.

[0087] If the judgment result is no, then compare the detected electrical signal with the detection threshold preset by the main control module of the background suppression sensor to judge whether there is an object in the target direction.

[0088] When the waveform of the detected electrical signal corresponding to the object exhibits an odd-symmetric characteristic and then deviates from the critical detection threshold range, and when the waveform change of the detected electrical signal corresponding to the object is extremely small at this time, without the hysteresis threshold, the sensor will immediately change the output state, which will cause the output of the background suppression photoelectric sensor to be too sensitive and the output state to change repeatedly. In view of this, the embodiment of the present application sets the hysteresis threshold to stabilize the output of the background suppression photoelectric sensor.

[0089] It can be understood that in practical applications, the background suppression photoelectric sensor realizes the judgment logic of steps 300 and S400 through the software algorithm of the main control module, and designers can make the logic of the algorithm different from the judgment logic of steps S300 and S400 of the embodiment of the present application through various algorithm forms and can achieve the same function. Obviously, without departing from the concept of steps S300 and S400 of the embodiment of the present application, this algorithm should still be regarded as the protection scope of the present application.

[0090] The background suppression photoelectric sensor provided by the embodiment of the present application presets the first detection distance as the equilibrium position of the target white object by adjusting the position of the transmitting lens, and calculates the equilibrium position of the target black object as the second detection distance based on the preset black-and-white difference. At the same time, by dynamically adjusting the position of the receiving lens, the waveforms of the detected electrical signals of the two objects exhibit odd-symmetric characteristics at the corresponding distances. At this time, the actual black-and-white difference of the background suppression sensor is the ratio of the difference between the first detection distance and the second detection distance to the first detection distance. The embodiment of the present application adjusts the black-and-white difference of the sensor according to the detection distances of the sensor for the target black object and the target white object, and can make the black-and-white difference of the dual-photodiode type background suppression photoelectric sensor not exceed 5%, solving the problem of the large black-and-white difference of the traditional dual-photodiode type background suppression photoelectric sensor.

[0091] The above content is a further detailed description of the present application in combination with specific implementation manners. It cannot be determined that the specific implementation of the present application is only limited to these descriptions. For those of ordinary skill in the technical field to which the present application pertains, without departing from the concept of the present application, several simple deductions or substitutions can still be made, which should all be regarded as the protection scope of the present application.

Claims

1. A background suppression photoelectric sensor, characterized in that, Including: An optical emission module, which includes a light source, an optical emission circuit, and an emission lens. The optical emission circuit is used to drive the light source to generate an emission optical signal, and the emission lens is used to focus the emission optical signal to a target direction; An optical reception module, which includes a reception lens, a dual photodiode, and an optical reception circuit. The reception lens is used to focus the reception optical signal reflected from the target direction to the dual photodiode. The dual photodiode is used to convert the reception optical signal into two electrical signals, and the optical reception circuit is used to convert the two electrical signals into a detection electrical signal; A main control module, which is used to compare the detection electrical signal with a preset detection threshold to determine whether there is an object in the target direction; Wherein, the emission lens is configured to: make the spot diameter of the emission optical signal after passing through the emission lens the smallest at a first detection distance; The reception lens is configured to: when a target black object is at a second detection distance, the waveform of the detection electrical signal generated by the optical reception circuit presents an odd symmetry characteristic, and when a target white object is at the first detection distance, the waveform of the detection electrical signal generated by the optical reception circuit presents an odd symmetry characteristic; The first detection distance and the second detection distance satisfy: the ratio of the difference between the first detection distance and the second detection distance to the first detection distance is the black-and-white difference of the background suppression photoelectric sensor; The main control module is configured to: Set the waveform amplitude difference between the waveform of the second detection electrical signal and the waveform of the first detection electrical signal as a critical detection threshold range. The critical detection threshold range is used to judge whether the waveform amplitude of the detection electrical signal generated by the optical reception circuit is within the critical detection threshold range when the waveform of the detection electrical signal generated by the optical reception circuit presents an odd symmetry characteristic, If the judgment result is yes, output the result that there is an object in the target direction; If the judgment result is no, output the result that there is no object in the target direction; The second detection electrical signal is: the detection electrical signal generated by the optical reception circuit when the target black object is at the second detection distance; The first detection electrical signal is: the detection electrical signal generated by the optical reception circuit when the target white object is at the first detection distance.

2. The background suppression photoelectric sensor according to claim 1, wherein, The optical reception circuit includes: A differential amplification unit, which is used to perform differential amplification processing on the two electrical signals to generate a first electrical signal; A differentiation unit, which is used to perform differentiation processing on the first electrical signal to generate a second electrical signal; An inverse amplification unit, which is used to perform inverse amplification processing on the second electrical signal to generate the detection electrical signal.

3. A method for adjusting the black and white difference of a background suppression photoelectric sensor, characterized in that, Applied to the background suppression photoelectric sensor according to any one of claims 1 to 2, the method for adjusting the black-and-white difference of the background suppression photoelectric sensor includes: Preset the first detection distance as the equilibrium position of the target white object, determine the equilibrium position of the target black object according to the first detection distance and the preset black-and-white difference, and set the equilibrium position of the target black object as the second detection distance. The equilibrium position is the distance corresponding to when the waveform of the detection circuit generated by the optical reception circuit of the background suppression photoelectric sensor presents an odd symmetry characteristic; Adjust the position of the receiving lens of the background suppression photoelectric sensor so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic, and so that the waveform of the detection electrical signal generated by the light receiving circuit when the target white object is at the first detection distance exhibits an odd symmetry characteristic.

4. The method for adjusting the black and white difference of the background suppression photoelectric sensor according to claim 3, characterized in that, The step of presetting the first detection distance as the equilibrium position of the target white object includes: Adjust the position of the transmitting lens of the background suppression photoelectric sensor until the spot imaging of the transmitted optical signal focused by the transmitting lens at a preset first distance reaches a preset clarity. Select any position within a distance not exceeding the first distance from the transmitting lens and preset it as the first detection distance.

5. The method for adjusting the black and white difference of the background suppression photoelectric sensor according to claim 3, characterized in that, The step of determining the equilibrium position of the target black object according to the first detection distance and the preset black-and-white difference and setting the equilibrium position of the target black object as the second detection distance includes: Obtain the equilibrium position of the target black object according to the black-and-white difference equation. Wherein, the black-and-white difference equation is: 。 6. The method for adjusting the black-and-white difference of the background suppression photoelectric sensor according to claim 3, wherein The step of adjusting the position of the receiving lens of the background suppression photoelectric sensor so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic, and so that the waveform of the detection electrical signal generated by the light receiving circuit when the target white object is at the first detection distance exhibits an odd symmetry characteristic includes: Adjust the position of the receiving lens of the background suppression photoelectric sensor so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic. Obtain the waveform of the detection electrical signal generated by the light receiving circuit when the target white object is at the first detection distance, and determine whether the waveform of the detection electrical signal generated by the light receiving circuit when the target white object is at the first detection distance exhibits an odd symmetry characteristic. If the judgment result is yes, mark the positions of the transmitting lens and the receiving lens as the positions having the preset black-and-white difference. If the judgment result is no, return to execute the step: adjust the position of the receiving lens of the background suppression photoelectric sensor so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic until the judgment result is yes.

7. The method for adjusting the black-and-white difference of the background suppression photoelectric sensor according to claim 6, characterized in that, The step of adjusting the position of the receiving lens of the background suppression photoelectric sensor so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic includes: Adjust the distance position between the receiving lens and the dual photodiodes of the background suppression photoelectric sensor and / or adjust the distance between the receiving lens and the transmitting lens so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic.

8. The method for adjusting the black-and-white difference of the background suppression photoelectric sensor according to claim 3, wherein After the step of adjusting the position of the receiving lens of the background suppression photoelectric sensor so that the waveform of the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance exhibits an odd symmetry characteristic, and so that the waveform of the detection electrical signal generated by the light receiving circuit when the target white object is at the first detection distance exhibits an odd symmetry characteristic, it further includes: Setting the waveform amplitude difference between the waveform of the second detection electrical signal and the waveform of the first detection electrical signal as a critical detection threshold range, where the critical detection threshold range is used to determine whether the waveform amplitude of the detection electrical signal generated by the light receiving circuit is within the critical detection threshold range when the waveform of the detection electrical signal generated by the light receiving circuit exhibits an odd symmetry characteristic, If the judgment result is yes, then output the result that there is an object in the target direction of the background suppression photoelectric sensor; If the judgment result is no, then output the result that there is no object in the target direction of the background suppression photoelectric sensor; The second detection electrical signal is: the detection electrical signal generated by the light receiving circuit when the target black object is at the second detection distance; The first detection electrical signal is: the detection electrical signal generated by the light receiving circuit when the target white object is at the first detection distance.

9. The method for adjusting the black-and-white difference of the background suppression photoelectric sensor according to claim 8, characterized in that, After the step of setting the waveform difference between the waveform of the second detection electrical signal and the waveform of the first detection electrical signal as a critical detection threshold range, it further includes: Setting the preset first hysteresis threshold and the preset second hysteresis threshold as the hysteresis of the two critical values of the critical detection threshold range respectively, where the two critical values of the critical detection threshold range are the waveform amplitude of the first detection electrical signal and the waveform amplitude of the second detection electrical signal; The first hysteresis threshold and the second hysteresis threshold are used to determine whether the waveform amplitude of the detection electrical signal is between the first hysteresis threshold and the waveform amplitude of the first detection electrical signal or between the second hysteresis threshold and the waveform amplitude of the second detection electrical signal when the waveform of the detection electrical signal generated by the light receiving circuit exhibits an odd symmetry characteristic and then deviates from the critical detection threshold range, If the judgment result is yes, then output the result that there is an object in the target direction of the background suppression photoelectric sensor; If the judgment result is no, then compare the detection electrical signal with the detection threshold preset by the main control module of the background suppression photoelectric sensor to determine whether there is an object in the target direction.

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