Background suppression type photoelectric sensor

Abstract

The invention provides a background suppression type photoelectric sensor, and belongs to the technical field of photoelectric sensors, and the photoelectric sensor comprises a transmitting module which is used for transmitting a light beam towards a background; the receiving module is used for receiving a first light spot and a second light spot of the light beam reflected by a background or an object, generating a first light signal according to the first light spot and generating a second light signal according to the second light spot; the control module is connected with the transmitting module and the receiving module and used for outputting a detection result according to the first optical signal and the second optical signal, and the detection result at least comprises whether an object exists between the background suppression type photoelectric sensor and the background or not. The method has the beneficial effects that by comprehensively analyzing the light signals corresponding to the two light spots, the influence of the complex surface reflection characteristic on the measurement stability and reliability of the background suppression type sensor is effectively overcome, the stable and reliable measurement of the complex surface object is realized, meanwhile, the background interference is effectively suppressed, and the method is widely applied to the field of industrial automation.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric sensors, and in particular to a background suppression type photoelectric sensor. Background Art

[0002] Background Suppression (BGS) photoelectric sensors use the principle of triangulation to pre-measure and store the reflection characteristics of the background, that is, the voltage distribution of each pixel on the linear array receiving tube. During actual measurement, the light beam is emitted by the transmitting tube, and the light beam reflected by the measured object is received by the receiving tube. The received signal is compared with the pre-stored background signal to determine whether there is an object between the background and the sensor. The distance of the object can also be calculated based on the spot position of the reflected light beam on the receiving tube. BGS sensors are widely used in the field of discrete industrial automation for object detection, distance measurement, shape recognition, etc. due to their advantages such as being able to effectively suppress background object interference and being insensitive to object color and material.

[0003] Traditional BGS sensors are usually based on a single-transmitter and single-receiver structure. However, when the surface of the object being measured is complex, such as corrugated, rough, specular reflection characteristics or dark surface, these complex surfaces are prone to specular reflection, scattering, absorption and other phenomena, resulting in unstable light signals received by the receiving tube and reduced signal-to-noise ratio. For example, due to its irregular concave-convex structure, the corrugated surface will cause irregular changes in the direction of the reflected light beam; the rough surface will cause scattering, reducing the intensity of the reflected light; specular reflection will cause the reflected light to be concentrated in a specific direction and may not be effectively received by the receiver; the dark surface will absorb most of the incident light, resulting in a weak reflected light signal. Especially for corrugated surfaces, due to the irregular concave-convex structure on the surface, traditional single-transmitter and single-receiver BGS sensors often receive light spots close to the background on the irregular surface, and are prone to misjudge these specific points as the background, causing the sensor to give incorrect outputs and miss detection.

[0004] Taking Omron's E3Z-LS61 / -66 / -81 / -86 background / foreground suppression sensor as an example, when measuring objects with a large amount of reflected light but diverging in random directions and with a concave and convex glossy surface, due to the movement of the measured object, the reflected light sometimes temporarily returns to the light receiving side, so an OFF delay timer is required to prevent high-speed vibration. Although the background / foreground suppression sensor is not easily affected by the color of the detected object or the background object, it may be affected by the speckle effect when facing objects with complex surfaces. Due to the optical effects caused by complex surfaces and the misjudgment of the background, BGS sensors based on a single-transmitter and single-receiver structure are often difficult to measure reliably. Therefore, the industry urgently needs a background suppression photoelectric sensor that can reliably measure objects with complex surfaces and effectively suppress background interference. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a background suppression type photoelectric sensor.

[0006] The technical problem solved by the present invention can be achieved by adopting the following technical solutions:

[0007] A background suppression photoelectric sensor, comprising:

[0008] A transmitting module, used for transmitting a light beam toward a background;

[0009] A receiving module, configured to receive a first light spot and a second light spot of the light beam reflected by the background or the object, generate a first light signal according to the first light spot, and generate a second light signal according to the second light spot;

[0010] The control module is connected to the transmitting module and the receiving module respectively, and is used to output a detection result according to the first optical signal and the second optical signal, wherein the detection result at least includes whether there is an object between the background suppression type photoelectric sensor and the background.

[0011] Preferably, the receiving module comprises a first receiving tube array;

[0012] The transmitting module comprises:

[0013] A first emitting unit, used for emitting a first light beam, wherein the first light beam forms the first light spot on the first receiving tube array;

[0014] The second emitting unit is used for emitting a second light beam, and the second light beam forms the second light spot on the first receiving tube array.

[0015] Preferably, the receiving module comprises a first receiving tube array and a second receiving tube array;

[0016] The transmitting module comprises:

[0017] The first emitting unit is used for emitting a first light beam, wherein the first light beam forms the first light spot on the first receiving tube array, and the first light beam forms the second light spot on the second receiving tube array.

[0018] Preferably, the receiving module comprises a first receiving tube array and a second receiving tube array;

[0019] The transmitting module comprises:

[0020] A first emitting unit, used for emitting a first light beam, wherein the first light beam forms the first light spot on the first receiving tube array;

[0021] The second emitting unit is used for emitting a second light beam, and the second light beam forms the second light spot on the second receiving tube array.

[0022] Preferably, the control module comprises:

[0023] a deviation calculation unit, configured to perform deviation calculation on detection parameters in the first optical signal and the second optical signal according to pre-calibrated standard detection parameters to obtain deviation calculation results; the detection parameters in the first optical signal and the second optical signal respectively include light spot centroid position information and light intensity distribution information;

[0024] The deviation analysis unit is connected to the deviation calculation unit and is used to analyze the deviation calculation result to determine the detection result.

[0025] Preferably, the deviation analysis unit comprises:

[0026] The first deviation analysis subunit is configured to output a detection result for determining whether an object exists between the background suppression type photoelectric sensor and the background when any detection parameter in the deviation calculation result exceeds a corresponding preset parameter threshold.

[0027] Preferably, the detection result also includes whether the surface of the object is a complex surface;

[0028] The deviation analysis unit also includes:

[0029] A second deviation analysis subunit is used to output a detection result that determines that there is an object between the background suppression type photoelectric sensor and the background and the surface of the object is a complex surface when the difference between the light spot centroid position information in the first light signal and the second light signal exceeds a preset difference threshold and the light intensity distribution information of the first light signal is less than a preset scattered light threshold or the light intensity distribution information of the second light signal is greater than a preset mirror reflection threshold.

[0030] Preferably, the control module further includes:

[0031] The background calibration unit is used to calibrate the target background, obtain the background light signal generated by the light spot reflected by the target background, and determine the pre-calibrated standard detection parameters according to the background light signal.

[0032] Preferably, the control module further includes:

[0033] The dynamic calibration unit is used to call the background calibration unit to dynamically calibrate the pre-calibrated standard detection parameters when a change in the background is detected.

[0034] Preferably, the dynamic calibration unit is also used to continuously monitor the deviation calculation result, and determine that the background has changed when the change rate of the moving average value of the deviation calculation result is less than a preset change rate threshold and the duration exceeds a preset time threshold.

[0035] The advantages or beneficial effects of the technical solution of the present invention are:

[0036] The present invention effectively overcomes the influence of complex surface reflection characteristics on the measurement stability and reliability of background suppression sensors by comprehensively analyzing the light signals corresponding to the two light spots, thereby achieving stable and reliable measurement of objects with complex surfaces and effectively suppressing background interference. It is widely used in the field of industrial automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural block diagram of a background suppression type photoelectric sensor in a preferred embodiment of the present invention;

[0038] Figure 2 This is a schematic structural diagram of a background suppression photoelectric sensor based on dual-transmitter and single-receiver in a preferred embodiment 1 of the present invention;

[0039] Figure 3 This is a structural block diagram of a control module in a preferred embodiment of the present invention;

[0040] Figure 4 A diagram showing the relationship between the centroid position and distance of a light spot in a preferred embodiment of the present invention;

[0041] Figure 5 It is a structural schematic diagram of a background suppression type photoelectric sensor based on single emission and dual reception in a preferred embodiment 2 of the present invention;

[0042] Figure 6 It is a schematic structural diagram of a background suppression photoelectric sensor based on dual emission and dual reception in a preferred embodiment 3 of the present invention.

[0043] Description of reference numerals:

[0044] 1. Transmitting module; 11. First transmitting unit; 111. First transmitting tube; 112. First lens; 12. Second transmitting unit; 121. Second transmitting tube; 122. Second lens; 2. Receiving module; 21. First receiving tube array; 211. First receiving tube; 212. Third lens; 22. Second receiving tube array; 221. Second receiving tube; 222. Fourth lens; 3. Control module; 31. Deviation calculation unit; 32. Deviation analysis unit; 321. First deviation analysis subunit; 322. Second deviation analysis subunit; 33. Background calibration unit; 34. Dynamic calibration unit; 3A. First control module; 3B. Second control module; 4. Power module; 4A. First power module; 4B. Second power module; 5. Communication module; 5A. First communication module; 5B. Second communication module; A. Background; L. Light beam; L1. First light beam; L2. Second light beam;

[0045] in, Figure 2 , Figure 5 and Figure 6 B1, B1', and B1" are respectively the first optical signals in Examples 1-3; B2, B2', and B2" are respectively the second optical signals in Examples 1-3. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0048] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0049] See also Figure 1 In a preferred embodiment of the present invention, based on the above problems existing in the prior art, a background suppression type photoelectric sensor is provided, comprising:

[0050] A transmitting module 1 is used to transmit a light beam L toward a background A;

[0051] A receiving module 2, used for receiving a first light spot F1 and a second light spot F2 of the light beam L reflected by the background A or an object, generating a first light signal according to the first light spot F1 and generating a second light signal according to the second light spot F2;

[0052] The control module 3 is connected to the transmitting module 1 and the receiving module 2 respectively, and is used to output a detection result according to the first optical signal and the second optical signal, and the detection result at least includes whether there is an object between the background suppression type photoelectric sensor and the background.

[0053] Specifically, the existing BGS sensor is based on a single-transmitter and single-receiver structure, and is often difficult to measure reliably due to optical effects caused by complex surfaces and misjudgment of the background.

[0054] In the embodiment of the present invention, by comprehensively analyzing the light signals corresponding to the two light spots, the influence of complex surface reflection characteristics on the measurement stability and reliability of the background suppression sensor is effectively overcome, and stable and reliable measurement of objects with complex surfaces is achieved. At the same time, background interference is effectively suppressed, and it is widely used in the field of industrial automation.

[0055] Based on this, the present invention utilizes the principle of triangulation ranging and proposes a background suppression photoelectric sensor based on dual-transmission and single-reception / single-transmission and dual-reception / dual-transmission and dual-reception, which can effectively improve the measurement reliability of objects with complex surfaces and has strong background suppression capabilities. It has broad application prospects in fields such as industrial automation.

[0056] The following is a further description of the background suppression photoelectric sensor based on dual-transmitter and single-receiver / single-transmitter and dual-receiver:

[0057] Example 1

[0058] like Figure 2 As shown, an embodiment of the present invention provides a background suppression photoelectric sensor based on dual transmission and single reception and a measurement method thereof. The sensor includes a transmitting module 1, a receiving module 2, and a control module 3.

[0059] As a preferred embodiment, the receiving module 2 includes a first receiving tube array 21;

[0060] The transmitting module 1 comprises:

[0061] The first emitting unit 11 is used to emit a first light beam L1, and the first light beam L1 forms a first light spot F1 on the first receiving tube array 21;

[0062] The second emitting unit 12 is used for emitting a second light beam L2 . The second light beam L2 forms a second light spot F2 on the first receiving tube array 21 .

[0063] Specifically, the background suppression type photoelectric sensor in the embodiment of the present invention adopts a dual-transmitter and single-receiver structure, that is, the transmitting module 1 includes two transmitting units, and the receiving module 2 includes one receiving unit. The two transmitting units are used to transmit light beams to the object to be measured or the background, and the one receiving unit is used to receive the light spots reflected by the light beams emitted by the two transmitting units through the object to be measured or the background.

[0064] Each transmitting unit includes a transmitting tube, namely a first transmitting tube 111 and a second transmitting tube 112. The two transmitting tubes transmit light beams to the object to be measured or the background at different angles or wavelengths.

[0065] Exemplarily, the transmitting tube may include but is not limited to LED, laser diode, etc.

[0066] Furthermore, each emitting unit may also include a lens, namely a first lens 112 and a second lens 122, for processing the light beams generated by the corresponding emitting tubes, so that the light beams emitted from the emitting tubes to the surroundings are converted into parallel light through the lenses, thereby forming the desired light spots.

[0067] Exemplarily, the lens may be a plano-convex lens, with the plane of the plano-convex lens disposed toward the transmitting tube and the convex surface disposed toward the background A. Of course, the present invention is not limited thereto, and other lenses may also be used.

[0068] Each receiving unit may include a receiving tube array, and the receiving tube array includes a plurality of first receiving tubes 211 for converting received optical signals into electrical signals.

[0069] Specifically, the plurality of first receiving tubes 211 are combined in a certain arrangement to form a linear array structure. For example, the plurality of first receiving tubes 211 are arranged horizontally or vertically to form a one-dimensional linear array structure. For another example, the plurality of first receiving tubes 211 can also be arranged horizontally and vertically to form a two-dimensional linear array structure. The embodiment of the present invention takes a one-dimensional linear array structure formed by 8 first receiving tubes 211 arranged vertically as an example.

[0070] Exemplarily, the receiving module 2 may be implemented by using a CMOS linear array sensor.

[0071] Furthermore, each receiving unit may also include a lens, namely, a third lens 212, which is used to collect the light beam reflected by the object to be measured or the background, and image it on the receiving tube array.

[0072] Similarly, the third lens 212 may also be a plano-convex lens, with the plane of the plano-convex lens disposed toward the receiving tube array and the convex surface disposed toward the background A.

[0073] The control module 3 is used to control the working sequence of the transmitting module 1 and the receiving module 2, for example, to control the two transmitting tubes to transmit alternately, and synchronously control the first receiving tube array 21 to collect data. The control module 3 is also used to calculate according to the optical signal collected by the first receiving tube array 21, obtain distance information and light intensity information, and perform deviation calculation and analysis to determine whether there is an object and the surface characteristics of the object.

[0074] Furthermore, the control module 3 controls the emission timing by controlling the emission start time and pulse width of each emission unit.

[0075] Furthermore, the control module 3 is also used to adjust the emission light intensity / emission waveform frequency / duty cycle, etc. of the emission unit, and the emission light intensity is adjusted by adjusting the driving current or voltage of the emission tube.

[0076] Exemplarily, the control module 3 may be a microcontroller unit (MCU), a digital signal processor (DSP), a field programmable gate array (FPGA), or the like.

[0077] As a preferred embodiment, the control module 3 further includes:

[0078] The background calibration unit 33 is used to calibrate the target background, obtain the background light signal generated by the light spot reflected by the light beam passing through the target background, and determine the pre-calibrated standard detection parameters according to the background light signal.

[0079] Specifically, in this embodiment, the background calibration unit 33 is used to record the background distance value corresponding to each emitting unit and the distribution of the background light intensity on each pixel receiving tube of the first receiving tube array 21 .

[0080] During background calibration, first, a known target background is placed at a set distance from the sensor; then, the first transmitting tube 111 and the second transmitting tube 112 are controlled to emit light beams respectively, and the first receiving tube array 21 receives the light beams reflected by the background. The control module 3 records the background distance value d1_background and the background light intensity distribution corresponding to the first transmitting tube 111, i.e., I11_background, I12_background...I1n_background; and simultaneously records the background distance value d2_background and the background light intensity distribution corresponding to the second transmitting tube 112, i.e., I21_background, I22_background...I2n_background, where the subscript n represents the number of first receiving tubes 211 on the first receiving tube array 21.

[0081] The pre-calibrated standard detection parameters include the above-mentioned d1_background, d2_background, I11_background, I12_background ... I1n_background and I21_background, I22_background ... I2n_background.

[0082] After background calibration, the sensor enters real-time measurement mode, controls the first transmitting tube 111 and the second transmitting tube 112 to alternately transmit light beams, and the first receiving tube array 21 synchronously receives the light beams reflected by the background or the object under test. The control module 3 calculates the detection parameters corresponding to each transmitting unit according to the received light signal, such as the real-time distance value and the light intensity distribution information, that is, the real-time distance value d1 and the light intensity distribution I11, I12...I1n corresponding to the first transmitting tube 111, and the real-time distance value d2 and the light intensity distribution I21, I22...I2n corresponding to the second transmitting tube 112.

[0083] The distance value d1 is calculated based on the intensity distribution I11, I12...I1n of the light spots on the first receiving tube array 21, and the distance value d2 is calculated based on the intensity distribution I21, I22...I2n of the light spots. The specific algorithm may be: calculating the centroid position of the light spots, which corresponds to the distance value, such as Figure 4 The relationship between the spot centroid position and distance is shown.

[0084] As a preferred embodiment, wherein Figure 3 As shown, the control module 3 includes:

[0085] The deviation calculation unit 31 is used to perform deviation calculation on the detection parameters in the first light signal and the second light signal according to the pre-calibrated standard detection parameters to obtain the deviation calculation result; the detection parameters in the first light signal and the second light signal respectively include the light spot centroid position information and the light intensity distribution information;

[0086] The deviation analysis unit 32 is connected to the deviation calculation unit 31 and is used to analyze the deviation calculation result to determine the detection result.

[0087] Specifically, in this embodiment, the deviation calculation unit 31 is used to calculate the distance deviation corresponding to each transmitting unit and the light intensity distribution deviation corresponding to each transmitting tube as the deviation calculation result.

[0088] The deviation calculation result includes the distance deviation Δd1 corresponding to the first transmitting tube 111, the distance deviation Δd2 corresponding to the second transmitting tube 112, the light intensity distribution deviations ΔI11, ΔI12 ... ΔI1n corresponding to the first transmitting tube 111, and the light intensity distribution deviations ΔI21, ΔI22 ... ΔI2n corresponding to the second transmitting tube 112. Wherein:

[0089] Δd1=d1-d1_background

[0090] Δd2=d2-d2_background

[0091] The light intensity distribution deviation corresponding to the first transmitting tube 111 is:

[0092] ΔI11=I11-I11_background

[0093] ΔI12=I12-I12_background ...

[0095] ΔI1n=I1n-I1n_background

[0096] The light intensity distribution deviation corresponding to the second transmitting tube 112 is:

[0097] ΔI21=I21-I21_background

[0098] ΔI22=I22-I22_background ...

[0100] ΔI2n=I2n-I2n_background

[0101] The deviation analysis unit 32 is used to determine whether there is an object between the sensor and the set background based on a preset algorithm according to the distance deviations Δd1, Δd2, and the light intensity distribution deviations ΔI12...ΔI1n, ΔI21, ΔI22...ΔI2n. The deviation analysis unit 32 can also further determine the surface characteristics of the object, such as whether the surface of the object is a complex surface.

[0102] The preset algorithm is a threshold judgment algorithm. As a preferred embodiment, the deviation analysis unit 32 includes:

[0103] The first deviation analysis subunit 321 is used to output a detection result of determining that there is an object between the background suppression type photoelectric sensor and the background when any detection parameter in the deviation calculation result exceeds a corresponding preset parameter threshold.

[0104] Specifically, in this embodiment, the state of the surface of the object being measured is judged based on the comparison results of the values ​​of Δd1 and Δd2 with the preset distance threshold, and the comparison results of the values ​​of ΔI11, ΔI12 ... ΔI1n, ΔI21, ΔI22 ... ΔI2n with the preset light intensity threshold.

[0105] When the distance deviation Δd1 or Δd2 is greater than the distance threshold distance_th, or any one or more of the light intensity distribution deviations ΔI11, ΔI12 ... ΔI1n, ΔI21, ΔI22 ... ΔI2n is greater than the light intensity threshold intensity_th, it is determined that there is an object between the sensor and the set background.

[0106] The preset algorithm is a difference comparison algorithm. As a preferred embodiment, the detection result also includes whether the surface of the object is a complex surface;

[0107] The deviation analysis unit 32 further includes:

[0108] The second deviation analysis subunit 322 is used to output a detection result that determines that there is an object between the background suppression photoelectric sensor and the background and the surface of the object is a complex surface when the difference between the light spot centroid position information in the first light signal and the second light signal exceeds a preset difference threshold and the light intensity distribution information of the first light signal is less than a preset scattered light threshold or the light intensity distribution information of the second light signal is greater than a preset mirror reflection threshold.

[0109] Specifically, in this embodiment, whether the surface of the object to be measured is a complex surface is determined based on the value of |d1-d2| and the distribution of the values ​​of I11, I12 ... I1n, I21, I22 ... I2n.

[0110] When |d1-d2| is greater than the difference threshold diff_th, and all values ​​in I11, I12...I1n are less than the scattered light threshold scatter_th (scattered light cannot return to the sensor) or all values ​​in I21, I22...I2n are greater than the specular reflection threshold specular_th, it is determined that a complex surface or edge, or a light-absorbing object that is very different from the background is detected, and it is determined that there is an object between the sensor and the background.

[0111] Furthermore, the algorithm may be preset as a more complex algorithm, for example, by using statistics including but not limited to calculating variance, standard deviation, etc., to analyze the numerical distribution of light intensity distribution I11, I12 ... I1n, I21, I22 ... I2n to more accurately determine the surface characteristics.

[0112] As a preferred embodiment, the control module 3 further includes:

[0113] The dynamic calibration unit 34 is used to call the background calibration unit to dynamically calibrate the pre-calibrated standard detection parameters when a change in the background is detected.

[0114] As a preferred embodiment, the dynamic calibration unit 34 is also used to continuously monitor the deviation calculation results, and determine that the background has changed when the change rate of the moving average of the deviation calculation results is less than a preset change rate threshold and the duration exceeds a preset time threshold.

[0115] Specifically, in this embodiment, in order to improve the long-term stability of the sensor, the control module 3 may adopt a dynamic calibration strategy to determine whether the background value needs to be recalibrated according to the long-term variation trends of the distance deviation and the light intensity distribution deviation.

[0116] Specifically, when the sensor is in a non-triggered state (i.e., when no object is detected), the changes in Δd1, Δd2, ΔI11, ΔI12...ΔI1n, ΔI21, ΔI22...ΔI2n are continuously monitored, and the moving average of Δd1, Δd2, ΔI11, ΔI12...ΔI1n, ΔI21, ΔI22...ΔI2n is calculated (for example, the average of the past N sampling values, or the average over a period of time, such as 1 hour. The sampling period and the number of samples for average value calculation can be set as needed. For example, sampling is performed once every 1 minute, and the average of the past 60 times is calculated, which is the average of the past hour).

[0117] When the rate of change of the moving average values ​​of Δd1 and Δd2 is less than the preset rate of change threshold rate_th_d and the duration exceeds the preset time threshold time_th_d, and the rate of change of the moving average values ​​of ΔI11, ΔI12...ΔI1n, ΔI21, ΔI22...ΔI2n is less than the preset rate of change threshold rate_th_I and the duration exceeds the preset time threshold time_th_I, it is determined that the background has changed slowly and a dynamic calibration strategy needs to be executed.

[0118] The control module 3 adopts different dynamic calibration algorithms according to the application scenarios of the sensor, such as adaptive adjustment, fixed time interval calibration or event-triggered calibration.

[0119] Adaptive adjustment: Automatically update the background values ​​d1_background, d2_background, I11_background, I12_background ... I1n_background, I21_background, I22_background ... I2n_background according to the current values ​​of Δd1, Δd2, ΔI11, ΔI12 ... ΔI1n, ΔI21, ΔI22 ... ΔI2n.

[0120] Fixed time interval calibration: re-execute the background calibration step at fixed time intervals (eg, 24 hours).

[0121] Event-triggered calibration: When a specific event is detected (e.g., device restart, maintenance operation, etc.), background calibration is triggered.

[0122] Furthermore, the sensor may also include: a power module 4 and a communication module 5. The power module 4 is used to supply power to the entire sensor. The communication module 5 is used to communicate with external devices, receive control instructions and configure system parameters of the sensor.

[0123] The communication module 5 may be implemented by, but is not limited to, an IO-LINK module, a 485 bus interface, a USB bus interface, an I 2 C bus interface, Bluetooth module or WIFI module, etc.

[0124] An embodiment of the present invention proposes a measurement method based on a background suppression type photoelectric sensor with dual transmission and single reception. The measurement method includes the steps of background calibration, real-time object measurement, deviation calculation, deviation analysis and dynamic calibration. By comparing the difference between the measured value and the background value and combining with preset algorithms, such as a threshold judgment algorithm and a difference comparison algorithm, it is determined whether an object exists and the surface characteristics of the object.

[0125] Specifically, the measuring method includes the following steps:

[0126] a, Background calibration:

[0127] 1) Place a known target background at a set distance from the sensor;

[0128] 2) Control the first transmitting tube 111 and the second transmitting tube 112 to transmit light beams respectively;

[0129] 3) The first receiving tube array 21 receives the light beam reflected by the background, and the control module 3 records the background distance values ​​d1_background and d2_background and the background light intensity distribution I11_background, I12_background ... I18_background, I21_background, I22_background ... I28_background (taking the receiving tube array as an example with 8 pixel receiving tubes), thus completing the pre-calibration of the standard detection parameters.

[0130] b. Real-time object measurement:

[0131] 1) After background calibration, the sensor enters real-time measurement mode.

[0132] 2) The control module 3 controls the first emitting tube 111 and the second emitting tube 112 to emit light beams alternately.

[0133] 3) The first receiving tube array 21 synchronously receives the light beam reflected by the background or the object to be measured, and the control module 3 calculates the detection parameters corresponding to each transmitting tube according to the received light signal, that is, the real-time distance value d1 and light intensity distribution I11, I12...I18 corresponding to the first transmitting tube 111, and the real-time distance value d2 and light intensity distribution I21, I22...I28 corresponding to the second transmitting tube 112. Among them, the distance value corresponds to the centroid position of the light spot, that is, the distance value d1 is calculated according to the light intensity distribution I11, I12...I18, and the distance value d2 is calculated according to the light intensity distribution I21, I22...I2n.

[0134] c, Deviation calculation:

[0135] 1) Calculate the distance deviation Δd1 and Δd2 corresponding to each launch tube:

[0136] Δd1=d1-d1_background

[0137] Δd2=d2-d2_background

[0138] 2) Calculate the light intensity distribution deviation corresponding to the first transmitting tube 111:

[0139] ΔI11=I11-I11_background

[0140] ΔI12=I12-I12_background ...

[0142] ΔI18=I18-I18_background

[0143] 3) Calculate the light intensity distribution deviation corresponding to the second transmitting tube 112:

[0144] ΔI21=I21-I21_background

[0145] ΔI22=I22-I22_background ...

[0147] ΔI28=I28-I28_background

[0148] d. Deviation analysis:

[0149] The control module 3 determines whether there is an object between the sensor and the set background and the surface characteristics of the object according to the values ​​of the distance deviations Δd1, Δd2 and the light intensity distribution deviations ΔI11, ΔI12 ... ΔI18, ΔI21, ΔI22 ... ΔI28 and a preset algorithm.

[0150] The preset algorithm is a threshold judgment algorithm. When the distance deviation Δd1 or Δd2 is greater than the distance threshold distance_th, or any one or more of the light intensity distribution deviations ΔI11, ΔI12 ... ΔI1n, ΔI21, ΔI22 ... ΔI2n is greater than the light intensity threshold intensity_th, it is determined that there is an object between the sensor and the set background.

[0151] The preset algorithm is the difference comparison algorithm. When |d1-d2| is greater than the difference threshold diff_th, and all values ​​in I11, I12...I1n are less than the scattered light threshold scatter_th or all values ​​in I21, I22...I2n are greater than the specular reflection threshold specular_th, it is determined that a complex surface or edge, or a light-absorbing object that is very different from the background is detected, and it is determined that there is an object between the sensor and the background.

[0152] Furthermore, more complex statistical algorithms including but not limited to calculating variance, standard deviation, etc. may be used to analyze the numerical distribution of light intensity distributions I11, I12 ... I1n, I21, I22 ... I2n to more accurately determine surface characteristics.

[0153] e, Dynamic calibration:

[0154] In order to improve the long-term stability of the sensor, the control module 3 can adopt a dynamic calibration strategy. When the sensor is in a non-trigger state (i.e., when no object is detected), the changes of Δd1, Δd2, ΔI11, ΔI12 ... ΔI1n, ΔI21, ΔI22 ... ΔI2n are continuously monitored, and the moving averages of Δd1, Δd2, and ΔI11, ΔI12 ... ΔI1n, ΔI21, ΔI22 ... ΔI2n are calculated.

[0155] When the rate of change of the moving average values ​​of Δd1 and Δd2 is less than the preset rate of change threshold rate_th_d and the duration exceeds the preset time threshold time_th_d, and the rate of change of the moving average values ​​of ΔI11, ΔI12...ΔI1n, ΔI21, ΔI22...ΔI2n is less than the preset rate of change threshold rate_th_I and the duration exceeds the preset time threshold time_th_I, it is determined that the background has changed slowly and the dynamic calibration strategy is executed.

[0156] The control module 3 adopts different dynamic calibration algorithms according to the application scenarios of the sensor, such as adaptive adjustment, fixed time interval calibration or event-triggered calibration.

[0157] Example 2

[0158] like Figure 5 As shown, this embodiment provides a triangulation ranging background suppression type photoelectric sensor based on single transmission and dual reception. The difference from Embodiment 1 is that the transmitting module 1 includes a transmitting unit, and the receiving module 2 includes two receiving units. The two receiving units are respectively located on both sides of the transmitting unit, and are used to receive reflected light at different angles.

[0159] As a preferred embodiment, the receiving module 2 includes a first receiving tube array 21 and a second receiving tube array 22;

[0160] The transmitting module 1 comprises:

[0161] The first emitting unit 11 is used for emitting a first light beam L1 . The first light beam L1 forms a first light spot F1 on the first receiving tube array 21 , and the first light beam L1 forms a second light spot F2 on the second receiving tube array 22 .

[0162] Specifically, the first receiving tube array 21 and the second receiving tube array 22 are respectively located on two sides of the first transmitting unit 11 and are used to receive reflected light at different angles.

[0163] Similarly, the second receiving tube array 22 has the same structure as the first receiving tube array 21 of Embodiment 1, and includes a second receiving tube 221 and a fourth lens 222 .

[0164] The other structures and working principles of the measurement method of this embodiment are similar to those of Embodiment 1 and will not be described in detail here.

[0165] Example 3

[0166] like Figure 6 As shown, this embodiment provides a triangulation ranging background suppression type photoelectric sensor based on dual transmission and dual reception. The difference from the embodiment 1 is that the receiving module 2 includes two receiving units.

[0167] As a preferred embodiment, the receiving module 2 includes a first receiving tube array 21 and a second receiving tube array 22;

[0168] The transmitting module 1 comprises:

[0169] The first emitting unit 11 is used to emit a first light beam L1, and the first light beam L1 forms a first light spot F1 on the first receiving tube array 21;

[0170] The second emitting unit 12 is used for emitting a second light beam L2 . The second light beam L2 forms a second light spot F2 on the second receiving tube array 22 .

[0171] Specifically, the sensor of the embodiment of the present invention includes two transmitting units and two receiving units, which can be arranged as needed, for example, the two transmitting units can be placed on both sides and the two receiving units can be placed in the middle; or the two transmitting units and the two receiving units can be placed crosswise.

[0172] The other structures and working principles of this embodiment are similar to those of Embodiment 1 and will not be described in detail here.

[0173] Furthermore, in the sensor of the third embodiment, when the first receiving tube array 21 is synchronized with the first transmitting unit 11 and the second receiving tube array 22 is synchronized with the second transmitting unit 12, the sensor is in a dual-transmitting and dual-receiving mode.

[0174] In the dual-transmit dual-receive mode, the first transmitting unit 11 and the second transmitting unit 12 adopt time-sharing transmission. At this time, the first receiving tube 211 of the first receiving tube array 21 is phase-locked to the transmission time of the first transmitting tube 111, so the first receiving tube 211 will not receive the signal of the second transmitting tube 121; similarly, the second receiving tube 221 of the second receiving tube array 22 is phase-locked to the transmission time of the second transmitting tube 121, and the second receiving tube 221 will not receive the signal of the first transmitting tube 111.

[0175] When the first receiving tube array 21 and the second receiving tube array 22 are both synchronized with the first transmitting unit 11 , the sensor is in a single-transmitting and dual-receiving mode.

[0176] In order to solve the problem of unstable and unreliable measurement of complex surface objects in the prior art, the embodiment of the present invention is based on the principle of triangulation ranging, and proposes a background suppression photoelectric sensor based on dual-transmission and single-reception / single-transmission and dual-reception / dual-transmission and dual-reception and a measurement method thereof, which can be used to stably measure objects with complex surfaces located on the background, thereby achieving stable and reliable measurement of complex surface objects.

[0177] The advantages or beneficial effects of adopting the above technical scheme are: the present invention adopts a dual-transmitter and single-receiver / single-transmitter and dual-receiver structure, and comprehensively analyzes the two light spots (dual-transmitter and single-receiver), the voltage value of the same light spot on two linear arrays (single-transmitter and dual-receiver), the voltage value of two light spots on two linear arrays (dual-transmitter and dual-receiver), the distance value between the sensor and the measured object, and the light intensity formed by the reflected light spots at different angles on the sensor linear array, thereby effectively overcoming the influence of complex surface reflection characteristics on the measurement stability and reliability of background suppression sensors, improving the reliability and reliability of background suppression sensors in measuring objects with complex surfaces, and can be widely used in industrial automation.

[0178] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of this specification and illustrations should be included in the protection scope of the present invention.

Claims

1. A background suppression type photoelectric sensor, characterized in that: include: A transmitting module, used for transmitting a light beam toward a background; A receiving module, configured to receive a first light spot and a second light spot of the light beam reflected by the background or the object, generate a first light signal according to the first light spot, and generate a second light signal according to the second light spot; The control module is connected to the transmitting module and the receiving module respectively, and is used to output a detection result according to the first light signal and the second light signal, wherein the detection result at least includes whether there is an object between the background suppression type photoelectric sensor and the background.

2. The background suppression type photoelectric sensor according to claim 1, characterized in that: The receiving module includes a first receiving tube array; The transmitting module comprises: A first emitting unit, used for emitting a first light beam, wherein the first light beam forms the first light spot on the first receiving tube array; The second emitting unit is used for emitting a second light beam, and the second light beam forms the second light spot on the first receiving tube array.

3. The background suppression type photoelectric sensor according to claim 1, characterized in that: The receiving module includes a first receiving tube array and a second receiving tube array; The transmitting module comprises: The first emitting unit is used for emitting a first light beam, wherein the first light beam forms the first light spot on the first receiving tube array, and the first light beam forms the second light spot on the second receiving tube array.

4. The background suppression type photoelectric sensor according to claim 1, characterized in that: The receiving module includes a first receiving tube array and a second receiving tube array; The transmitting module comprises: A first emitting unit, used for emitting a first light beam, wherein the first light beam forms the first light spot on the first receiving tube array; The second emitting unit is used for emitting a second light beam, and the second light beam forms the second light spot on the second receiving tube array.

5. The background suppression type photoelectric sensor according to claim 1, characterized in that: The control module comprises: a deviation calculation unit, configured to perform deviation calculation on detection parameters in the first optical signal and the second optical signal according to pre-calibrated standard detection parameters to obtain a deviation calculation result; the detection parameters in the first optical signal and the second optical signal respectively include light spot centroid position information and light intensity distribution information; The deviation analysis unit is connected to the deviation calculation unit and is used to analyze the deviation calculation result to determine the detection result.

6. The background suppression type photoelectric sensor according to claim 5, characterized in that: The deviation analysis unit comprises: The first deviation analysis subunit is used to output a detection result of determining whether an object exists between the background suppression type photoelectric sensor and the background when any detection parameter in the deviation calculation result exceeds a corresponding preset parameter threshold.

7. The background suppression type photoelectric sensor according to claim 5, characterized in that: The detection result also includes whether the surface of the object is a complex surface; The deviation analysis unit also includes: A second deviation analysis subunit is used to output a detection result that determines that there is an object between the background suppression type photoelectric sensor and the background and the surface of the object is a complex surface when the difference between the light spot centroid position information in the first light signal and the second light signal exceeds a preset difference threshold and the light intensity distribution information of the first light signal is less than a preset scattered light threshold or the light intensity distribution information of the second light signal is greater than a preset mirror reflection threshold.

8. The background suppression type photoelectric sensor according to claim 5, characterized in that: The control module also includes: The background calibration unit is used to calibrate the target background, obtain the background light signal generated by the light spot reflected by the target background, and determine the pre-calibrated standard detection parameters according to the background light signal.

9. The background suppression type photoelectric sensor according to claim 8, characterized in that: The control module also includes: The dynamic calibration unit is used to call the background calibration unit to dynamically calibrate the pre-calibrated standard detection parameters when a change in the background is detected.

10. The background suppression type photoelectric sensor according to claim 9, characterized in that: The dynamic calibration unit is also used to continuously monitor the deviation calculation result, and determine that the background has changed when the change rate of the moving average value of the deviation calculation result is less than a preset change rate threshold and the duration exceeds a preset time threshold.

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