A reflective photoelectric sensor and its anti-interference method

Abstract

This invention discloses a reflective photoelectric sensor, comprising: a control circuit for generating a transmitted electrical signal; a transmitting circuit connected to the control circuit for transmitting a transmitted light signal toward a detection target based on the transmitted electrical signal; a receiving circuit for receiving the reflected light signal reflected by the detection target and generating a reflected analog signal; a comparison circuit connected to the receiving circuit for generating a reflected electrical signal corresponding to the reflected analog signal; an AND gate circuit connected to the control circuit and the comparison circuit for performing an AND gate shaping on the transmitted and reflected electrical signals to obtain an AND gate output signal; and a processing circuit connected to the AND gate circuit and the control circuit for obtaining a detection result based on the AND gate output signal. If the AND gate output signal matches the transmitted electrical signal, it is determined that the detection target has been hit by the transmitted light signal. This invention also discloses an anti-interference method for the reflective photoelectric sensor, which can effectively improve the accuracy of the judgment of the detection result.

Description

Technical Field

[0001] This invention relates to the field of photoelectric sensor technology, and in particular to a reflective photoelectric sensor and its anti-interference method. Background Technology

[0002] Photoelectric sensors are widely used in industrial settings due to their advantages such as strong anti-interference capability, long detection distance, and low power consumption. A photoelectric sensor compares the received waveform with a fixed voltage level. When the echo signal exceeds a threshold, the comparison output generates a signal, thus determining whether a target is present.

[0003] When sensors are densely installed in the field, such as back-to-back or facing each other, sensor failure can occur if multiple sensors have the same or similar emission periods. For example, if sensor A and sensor B are installed close together, some of the diffused light emitted by sensor B will be reflected back to sensor A, causing sensor A to misidentify the target. Summary of the Invention

[0004] Therefore, it is necessary to propose a reflective photoelectric sensor and its anti-interference method to address the above problems.

[0005] A reflective photoelectric sensor includes: a control circuit for generating an emitted electrical signal; an emitted circuit connected to the control circuit for emitting an emitted light signal toward a detection target according to the emitted electrical signal; a receiving circuit for receiving the reflected light signal reflected by the detection target and generating a reflected analog signal; a comparison circuit connected to the receiving circuit for generating a reflected electrical signal corresponding to the reflected analog signal; an AND gate circuit connected to the control circuit and the comparison circuit for performing an AND gate shaping on the emitted electrical signal and the reflected electrical signal to obtain an AND gate output signal; and a processing circuit connected to the AND gate circuit and the control circuit for obtaining a detection result according to the AND gate output signal, wherein if the AND gate output signal matches the emitted electrical signal, it is determined that the detection target has been hit by the emitted light signal.

[0006] An anti-interference method for a reflective photoelectric sensor includes: acquiring a transmitted electrical signal; transmitting a transmitted optical signal to a detection target based on the transmitted electrical signal; receiving a reflected optical signal reflected by the detection target and generating a simulated reflected signal; generating a reflected electrical signal corresponding to the simulated reflected signal; performing AND gate shaping on the transmitted electrical signal and the reflected electrical signal to acquire an AND gate output signal; determining whether the AND gate output signal matches the transmitted electrical signal; if the AND gate output signal matches the transmitted electrical signal, determining that the detection target has been hit by the transmitted optical signal.

[0007] The embodiments of the present invention have the following beneficial effects:

[0008] By using an AND gate circuit in the reflective photoelectric sensor to shape the reflected and emitted electrical signals, pulses in the reflected electrical signal that are not formed due to the emitted light signal hitting the detection target are filtered out. The detection result is obtained based on the output signal of the filtered AND gate, which can effectively improve the accuracy of the judgment of the detection result. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] in:

[0011] Figure 1 This is a schematic diagram of the structure of the first embodiment of the reflective photoelectric sensor provided by the present invention;

[0012] Figure 2 This is a schematic diagram of the first embodiment of the signal waveform of the reflective photoelectric sensor provided by the present invention;

[0013] Figure 3 This is a schematic diagram of the structure of the second embodiment of the reflective photoelectric sensor provided by the present invention;

[0014] Figure 4 This is a schematic diagram of a second embodiment of the signal waveform of the reflective photoelectric sensor provided by the present invention;

[0015] Figure 5 This is a schematic diagram of the signal waveform of the third embodiment of the reflective photoelectric sensor provided by the present invention;

[0016] Figure 6 This is a schematic diagram of the signal waveform of the fourth embodiment of the reflective photoelectric sensor provided by the present invention;

[0017] Figure 7 This is a flowchart illustrating the first embodiment of the anti-interference method for the reflective photoelectric sensor provided by the present invention.

[0018] Figure 8 This is a flowchart illustrating the second embodiment of the anti-interference method for the reflective photoelectric sensor provided by the present invention. Detailed Implementation

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] When encountering densely installed sensors in the field, such as back-to-back or facing each other, if multiple sensors have the same or similar emission periods, it will lead to sensor failure.

[0021] To address the aforementioned issues, this embodiment provides a reflective photoelectric sensor that can effectively improve the accuracy of sensor detection.

[0022] Please refer to the following: Figure 1 , Figure 1 This is a schematic diagram of the structure of the first embodiment of the reflective photoelectric sensor provided by the present invention. The reflective photoelectric sensor 10 includes a control circuit 11, a transmitting circuit 12, a receiving circuit 13, a comparison circuit 14, an AND gate circuit 15, and a processing circuit 16.

[0023] Control circuit 11 is used to generate the transmitted electrical signal. Please refer to the relevant documentation. Figure 2 , Figure 2 This is a schematic diagram of the signal waveform of a first embodiment of the reflective photoelectric sensor provided by the present invention. Figure 2 As shown, the transmitted electrical signal is a pulse electrical signal with a fixed period. The user can input a transmission command to the control circuit 11, which may include parameters such as the duration of the fixed period of the transmitted electrical signal and the transmission pulse duration. The control circuit 11 generates the corresponding transmitted electrical signal based on the received transmission command.

[0024] The transmitting circuit 12 is connected to the control circuit 11, and transmits a light signal to the detection target according to the transmitted electrical signal, such as... Figure 2 As shown, when the transmitting electrical signal is at a high level, the transmitting circuit 12 transmits a transmitted light signal. If the transmitted light signal hits the detection target, the detection target will reflect the transmitted light signal, generating a reflected light signal.

[0025] The receiving circuit 13 is used to receive the reflected light signal from the target and generate a simulated reflection signal based on the reflected light signal. For example... Figure 2 As shown, the level of the simulated reflection signal is related to the intensity of the reflected light signal. The energy of the reflected light signal is amplified by the receiving circuit to generate the simulated reflection signal. In addition, the receiving circuit may also receive interference light from the outside world, and the generated simulated reflection signal also includes pulses in response to the interference light.

[0026] The comparator circuit 14 includes a comparator 141. The first input terminal 1411 of the comparator 141 is connected to the receiving circuit 13 for acquiring the reflected analog signal. The input terminal 1412 of the comparator 141 is connected to a reference level. The level of the reference level can be set by the user; for example, the level of the reference level is negatively correlated with the distance to the target, with a lower reference level for longer distances. The comparator 141 compares the reflected analog signal with the reference level, assigning a high level to the portion of the reflected analog signal that is higher than or equal to the reference level, and a low level to the portion that is lower than the reference level, thus generating a reflected electrical signal corresponding to the reflected analog signal.

[0027] AND gate circuit 15 is connected to comparator circuit 14, i.e., the output terminal 1413 of comparator 141, and is also connected to control circuit 11. It acquires the transmitted electrical signal and the reflected electrical signal, performs AND gate shaping on the transmitted electrical signal and the reflected electrical signal, so that the part where the transmitted electrical signal and the reflected electrical signal are both at a high level is corresponding to a high level, and the rest is at a low level, thus generating the AND gate output signal.

[0028] Processing circuit 16, AND gate circuit 15, and control circuit 11 determine whether the output signal of the AND gate and the transmitted electrical signal match. Figure 2 If the two signals match, it indicates that the target has been hit by the emitted light signal. Furthermore, the distance to the target can be calculated based on the AND gate output signal, and the time delay between the AND gate output signal and the emitted signal can be obtained. The distance to the target can then be calculated based on this time delay.

[0029] As described above, in this embodiment, the AND gate circuit of the reflective photoelectric sensor shapes the reflected electrical signal and the emitted electrical signal, filters out the pulses in the reflected electrical signal that are not formed due to the emitted light signal hitting the detection target, and obtains the detection result based on the output signal of the filtered AND gate, which can effectively improve the accuracy of the judgment.

[0030] Please see Figure 3 , Figure 3 This is a schematic diagram of the structure of the second embodiment of the reflective photoelectric sensor provided by the present invention. The reflective photoelectric sensor 20 includes a control circuit 201, a transmitting circuit 202, a receiving circuit 203, a comparison circuit 204, a delay circuit 205, a detection circuit 206, an adjustment circuit 207, an AND gate circuit 208, and a processing circuit 209. The connection relationship and function of the control circuit 201, the transmitting circuit 202, and the receiving circuit 203 are basically the same as those of the control circuit 11, the transmitting circuit 12, and the receiving circuit 13 of the first embodiment of the reflective photoelectric sensor provided by the present invention, and will not be described again here.

[0031] The delay circuit 205 is connected to the transmitting circuit 202 and is used to delay the operation of the transmitting circuit 202 in transmitting optical signals by a preset time. The user can input a custom preset delay time, for example, greater than 20ms and less than 50ms. A delay greater than 20ms ensures sufficient time to ensure that the first pulse synchronization eventually occurs as the reflective photoelectric sensor continuously shifts its frequency. A delay less than 50ms is in accordance with national standards requiring that the power-on delay not exceed 50ms. During the preset delay time, the transmitting circuit 202 is in a stopped state and does not transmit optical signals.

[0032] The detection circuit 206 is connected to the comparison circuit 204. Since the transmitting circuit 202 is in a stopped state, the reflected light signal received by the receiving circuit 203 at this time is an interference signal caused by the emitted light signals from other reflective photoelectric sensors. The comparison circuit 204 generates a reflected electrical signal corresponding to this interference signal, and the detection circuit 205 obtains the reflection time interval of the reflected electrical signal. For details, please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a schematic diagram of a second embodiment of the signal waveform of the reflective photoelectric sensor provided by the present invention.

[0033] like Figure 4 As shown, the reflected electrical signal has two high-level pulses within one reflection period T. The reflection time interval Td2 between these two high-level pulses is obtained. In other implementation scenarios, there may be multiple high-level pulses within one reflection period T. Since the interference signal is emitted by other reflective photoelectric sensors, the reflection time intervals between multiple high-level pulses are equal, and the reflection time interval between two adjacent high-level pulses can be obtained.

[0034] The adjustment circuit 207 is connected to the detection circuit 206 and the control circuit 201 to obtain the initial transmission time interval of the transmitted electrical signal, such as... Figure 4 As shown, the transmitted electrical signal has two high-level pulses within one transmission period T, and the transmission time interval between these two high-level pulses is Td1. Since the periods of both the reflected and transmitted electrical signals are T, if the reflection time interval Td2 is equal to the transmission time interval Td1, the transmission time interval Td1 needs to be adjusted to avoid misjudging the reflected analog signal caused by the detected interference signal as the reflected analog signal corresponding to the transmitted optical signal.

[0035] Furthermore, the adjusted launch time interval is calculated according to the following formula:

[0036] △T=2*|Td1-Td2|

[0037] Td1'=Td1+△T

[0038] Where Td1 is the original transmission time interval, Td2 is the reflection time interval, and Td1' is the adjusted transmission time interval.

[0039] AND gate 208 connects comparator circuit 204 and control circuit 201. When the preset time arrives, transmitter circuit 21 adjusts the transmission time interval of the transmission electrical signal and transmits a transmission optical signal to the detection target. Assuming the interference signals are transmitted simultaneously, i.e., the positions of the first high-level pulses in the same period T coincide, since the reflection time interval of the interference signal and the transmission time interval of the transmission electrical signal are not equal, the reflected electrical signal output by comparator circuit 24 may include three high-level pulses in one period T. AND gate circuit 28 performs AND gate shaping on the reflected electrical signal and the transmitted electrical signal to obtain the AND gate output signal. The AND gate output signal has two high-level pulses in each period.

[0040] In another implementation scenario, please refer to [the relevant documentation]. Figure 5 , Figure 5 This is a schematic diagram of the signal waveform of the reflective photoelectric sensor provided by the present invention in a third embodiment. If the emitted light signal fails to hit the detection target, the received reflected light signal is an interference signal. Assuming that the interference signals are emitted simultaneously, that is, the positions of the first high-level pulses coincide in the same period T, the reflected electrical signal output by the comparator circuit 204 may include two high-level pulses in one period T. The AND gate circuit 208 performs AND gate shaping on the reflected electrical signal and the emitted electrical signal to obtain the AND gate output signal. The AND gate output signal has only one high-level pulse in each period.

[0041] Processing circuit 209 is connected to AND gate circuit 208 and control circuit 201 to determine whether the output signal of the AND gate matches the transmitted electrical signal. Figure 4 The output signal of the AND gate matches the transmitted electrical signal; therefore, it can be determined that the target was hit by the transmitted light signal. Figure 5 The output signal of the AND gate and the transmitted electrical signal are mismatched, so it can be determined that the target was not hit by the transmitted light signal.

[0042] In another implementation scenario, please refer to [the relevant documentation]. Figure 6 , Figure 6 This is a schematic diagram of the fourth embodiment of the signal waveform of the reflective photoelectric sensor provided by the present invention. (See diagram below.) Figure 6As shown, in one period T, the transmitted electrical signal has three high-level pulses. If the transmitted light signal fails to hit the detection target, the received reflected light signal is an interference signal. Assuming the interference signals are transmitted simultaneously, that is, the positions of the first high-level pulses coincide within the same period T, the reflected electrical signal output by comparator circuit 204 may include three high-level pulses in one period T. AND gate circuit 208 performs AND gate shaping on the reflected and transmitted electrical signals to obtain the AND gate output signal. The AND gate output signal has only one high-level pulse per period.

[0043] Processing circuit 209 is connected to AND gate circuit 208 and control circuit 201 to determine whether the output signal of the AND gate matches the transmitted electrical signal. Figure 6 The output signal of the AND gate and the transmitted electrical signal are mismatched, so it can be determined that the target was not hit by the transmitted light signal.

[0044] As described above, in this embodiment, the operation delay of the reflected photoelectric sensor to emit the emitted light signal is preset for a preset time. The reflection time interval of the reflected electrical signal caused by the interference signal is obtained within the preset time. The emission time interval of the emitted electrical signal is adjusted according to the reflection time interval. This can avoid the influence of the interference signal on the judgment result of the processing circuit and improve the accuracy and reliability of the detection result judgment.

[0045] Please continue reading Figure 3 The reflective photoelectric sensor 20 also includes a first judgment circuit 210 and a calculation circuit 211.

[0046] The calculation circuit 211 is connected to the control circuit 21 and is used to obtain the transmission period and transmission pulse duration of the transmitted electrical signal from the control circuit 21. Based on the transmission period and transmission pulse duration, a preset threshold for the transmission time interval is calculated. The transmission pulse duration refers to the duration of a high-level pulse in the transmitted electrical signal. Specifically, the preset threshold for the transmission time interval is calculated according to the following formula:

[0047] Td max =2*Tp+T / 2

[0048] Where Tp is the transmission pulse time, T is the transmission period, and Td is the transmission period. max This is a preset threshold for the transmission time interval.

[0049] In other implementation scenarios, there may be n high-level pulses within one transmission cycle. The preset threshold for the transmission time interval is calculated using the following formula:

[0050] Td max =n*Tp+T / n

[0051] The first judgment circuit 210 connects the calculation circuit 211 and the adjustment circuit 209, and is used to determine whether the transmission time interval adjusted by the adjustment circuit 209 is greater than a preset threshold. If the adjusted transmission time interval is less than or equal to the preset threshold, the adjusted transmission time interval is used; if the adjusted transmission time interval is greater than the preset threshold, the transmission time interval is readjusted. Specifically, the transmission time interval is readjusted according to the following formula:

[0052] △T=2*|Td1-Td2|

[0053] Td1”=Td1-△T

[0054] Where Td1 is the original transmission time interval, Td2 is the reflection time interval, and Td1” is the readjusted transmission time interval.

[0055] As described above, in this embodiment, a preset threshold is calculated based on the transmission period and transmission pulse time of the transmitted electrical signal to avoid the adjusted transmission time interval being too large, which would cause changes in the transmission period and affect the judgment result, thereby improving the accuracy and reliability of the detection result judgment.

[0056] Please continue reading Figure 3 The reflective photoelectric sensor 20 also includes a second judgment circuit 212. The second judgment circuit 212 is connected to the detection circuit 206, the adjustment circuit 207, and the control circuit 201. The second judgment circuit 212 determines whether the transmitted electrical signal emitted by the control circuit 201 and the reflected electrical signal output by the detection circuit 206 are signals of the same frequency. If they are signals of the same frequency, the adjustment circuit 207 is activated to adjust the transmission time interval. If they are not signals of the same frequency, the adjustment circuit 207 is not activated. Interference signals of different frequencies can be shielded through the AND gate circuit 208.

[0057] As described above, in this embodiment, by judging whether the transmitted and reflected electrical signals are signals of the same frequency, it is determined whether to activate the adjustment circuit. Interference signals of different frequencies can be shielded through AND gate circuits. Without activating the adjustment circuit, the resource consumption required for judgment can be reduced and the resource utilization rate can be improved.

[0058] Please see Figure 7 , Figure 7 This is a schematic flowchart of the first embodiment of the anti-interference method for the reflective photoelectric sensor provided by the present invention. The anti-interference method for the reflective photoelectric sensor provided by the present invention includes the following steps:

[0059] S101: Acquire the transmitted electrical signal and transmit the transmitted optical signal to the detection target based on the transmitted electrical signal.

[0060] In a specific implementation scenario, a user-input transmission command can be obtained. This command may include parameters such as the fixed period duration of the transmitted electrical signal and the transmission pulse duration. A corresponding transmission electrical signal is then generated based on the received transmission command. For example... Figure 2 As shown, the transmitted electrical signal is a pulse electrical signal with a fixed period.

[0061] The system acquires the transmitted electrical signal and, based on this signal, transmits a transmitted optical signal towards the target. Specifically, in... Figure 2 In this system, when the transmitting electrical signal is at a high level, a transmitting optical signal is emitted. If the emitted optical signal hits the detection target, the detection target will reflect the emitted optical signal, generating a reflected optical signal.

[0062] S102: Receives the reflected light signal from the target and generates a simulated reflection signal.

[0063] In this implementation scenario, the reflected light signal from the target is received, and a simulated reflection signal is generated based on the reflected light signal. The level of the simulated reflection signal is related to the intensity of the reflected light signal; the energy of the reflected light signal is amplified by the receiving circuit to generate the simulated reflection signal. Furthermore, the receiving circuit may also receive interference light from external sources, and the generated simulated reflection signal also includes pulses responding to this interference light.

[0064] S103: Generate a reflected electrical signal corresponding to the reflected analog signal.

[0065] In this implementation scenario, a reference level is acquired. The level of the reference level can be set by the user. For example, the level of the reference level is negatively correlated with the distance to the target; the longer the distance, the lower the reference level. The reflected simulated signal is compared with the reference level. The portion of the reflected simulated signal that is higher than or equal to the reference level is assigned a high level, while the portion that is lower than the reference level is assigned a low level, thus generating a reflected electrical signal corresponding to the reflected simulated signal.

[0066] S104: Perform AND gate shaping on the transmitted and reflected electrical signals to obtain the AND gate output signal.

[0067] In this implementation scenario, the transmitted and reflected electrical signals are acquired, and the transmitted and reflected electrical signals are shaped by an AND gate. The part of the transmitted and reflected electrical signals that are both at a high level is corresponding to a high level, and the rest is at a low level, thus generating an AND gate output signal.

[0068] S105: Determine whether the AND gate output signal matches the transmitted electrical signal. If yes, proceed to step S106; otherwise, proceed to step S107.

[0069] In this implementation scenario, it is determined whether the time of the high-level pulse of the AND gate output signal matches the time of the high-level pulse of the transmitted electrical signal. For example, considering the time delay, the difference between the two is less than the preset duration.

[0070] S106: Determine that the target has been hit by the emitted light signal.

[0071] In this implementation scenario, such as Figure 2 As shown, if the AND gate output signal matches the transmitted electrical signal, it indicates that the target has been hit by the transmitted light signal. Furthermore, the distance to the target can be calculated based on the AND gate output signal, and the time delay between the AND gate output signal and the transmitted signal can be obtained. The distance to the target can then be calculated based on this time delay.

[0072] S107: Determine that the target was not hit by the emitted light signal.

[0073] In this implementation scenario, if the AND gate output signal does not match the transmitted electrical signal, it indicates that the target was not hit by the transmitted light signal.

[0074] As described above, in this embodiment, the reflected electrical signal and the transmitted electrical signal are shaped by an AND gate. Pulses in the reflected electrical signal that are not formed due to the transmitted light signal hitting the detection target are filtered out. The detection result is obtained based on the output signal of the filtered AND gate, which can effectively improve the accuracy of the judgment.

[0075] Please see Figure 8 , Figure 8 This is a schematic flowchart of the second embodiment of the anti-interference method for the reflective photoelectric sensor provided by the present invention. The anti-interference method for the reflective photoelectric sensor provided by the present invention includes the following steps:

[0076] S201: Acquire the transmitted electrical signal and transmit the transmitted optical signal to the detection target after a preset delay.

[0077] In a specific implementation scenario, the operation of transmitting the optical signal is delayed by a preset time. Users can input a custom preset delay time, for example, greater than 20ms and less than 50ms. A delay greater than 20ms ensures sufficient time for the first pulse synchronization to occur as the reflective photoelectric sensor continuously shifts its frequency. A delay less than 50ms is in accordance with national standards requiring that the power-on delay not exceed 50ms. During the preset delay time, no optical signal is transmitted.

[0078] S202: Receive the reflected light signal from the target and generate a simulated reflection signal.

[0079] S203: Generate a reflected electrical signal corresponding to the reflected analog signal.

[0080] In this implementation scenario, steps S202-S203 are basically the same as steps S102-S103 in the first embodiment of the anti-interference method for the reflective photoelectric sensor provided by the present invention.

[0081] S204: Determine whether the transmitted and reflected electrical signals are signals of the same frequency. If yes, proceed to step S205; otherwise, proceed to step S210.

[0082] In this implementation scenario, it is determined whether the transmitted and reflected electrical signals are signals of the same frequency, that is, whether the high-level pulse times and periods of the two signals are consistent.

[0083] S205: Obtain the reflection time interval of the reflected electrical signal corresponding to the reflected light signal.

[0084] In this implementation scenario, since no transmitted light signal is emitted, the received reflected light signal is an interference signal caused by the transmitted light signal emitted by other reflective photoelectric sensors. A reflected electrical signal corresponding to this interference signal is generated, and the reflection time interval of the reflected electrical signal is obtained. For details, please refer to... Figure 4 , Figure 4 This is a schematic diagram of a second embodiment of the signal waveform of the reflective photoelectric sensor provided by the present invention.

[0085] like Figure 4 As shown, the reflected electrical signal has two high-level pulses within one reflection period T. The reflection time interval Td2 between these two high-level pulses is obtained. In other implementation scenarios, there may be multiple high-level pulses within one reflection period T. Since the interference signal is emitted by other reflective photoelectric sensors, the reflection time intervals between multiple high-level pulses are equal, and the reflection time interval between two adjacent high-level pulses can be obtained.

[0086] S206: Adjust the transmission time interval of the transmitted electrical signal according to the reflection time interval.

[0087] In this implementation scenario, the initial transmission time interval of the transmitted electrical signal is obtained, such as... Figure 4 As shown, the transmitted electrical signal has two high-level pulses within one transmission period T, and the transmission time interval between these two high-level pulses is Td1. Since the periods of both the reflected and transmitted electrical signals are T, if the reflection time interval Td2 is equal to the transmission time interval Td1, the transmission time interval Td1 needs to be adjusted to avoid misjudging the reflected analog signal caused by the detected interference signal as the reflected analog signal corresponding to the transmitted optical signal.

[0088] Furthermore, the adjusted launch time interval is calculated according to the following formula:

[0089] △T=2*|Td1-Td2|

[0090] Td1'=Td1+△T

[0091] Where Td1 is the original transmission time interval, Td2 is the reflection time interval, and Td1' is the adjusted transmission time interval.

[0092] S207: Calculate the preset threshold based on the transmission period and transmission pulse time of the transmitted electrical signal.

[0093] In this implementation scenario, a preset threshold for the transmission time interval is calculated based on the transmission period and the transmission pulse duration. The transmission pulse duration refers to the duration of a high-level pulse in the transmitted electrical signal. Specifically, the preset threshold for the transmission time interval is calculated using the following formula:

[0094] Td max =2*Tp+T / 2

[0095] Where Tp is the transmission pulse time, T is the transmission period, and Td is the transmission period. max This is a preset threshold for the transmission time interval.

[0096] In other implementation scenarios, there may be n high-level pulses within one transmission cycle. The preset threshold for the transmission time interval is calculated using the following formula:

[0097] Td max =n*Tp+T / n

[0098] S208: Determine whether the adjusted transmission time interval is greater than the preset threshold. If yes, proceed to step S209; otherwise, proceed to step S210.

[0099] In this implementation scenario, the adjusted transmission time interval is compared with the calculated preset threshold.

[0100] S209: Readjust the launch time interval.

[0101] In this implementation scenario, if the adjusted transmission time interval is less than or equal to a preset threshold, the adjusted transmission time interval is used; if the adjusted transmission time interval is greater than the preset threshold, the transmission time interval is readjusted. Specifically, the transmission time interval is readjusted according to the following formula:

[0102] △T=2*|Td1-Td2|

[0103] Td1”=Td1-△T

[0104] Where Td1 is the original transmission time interval, Td2 is the reflection time interval, and Td1” is the readjusted transmission time interval.

[0105] S210: Acquire the transmitted electrical signal and transmit a transmitted optical signal to the detection target based on the transmitted electrical signal.

[0106] S211: Receives the reflected light signal from the target and generates a simulated reflection signal;

[0107] S212: Generate a reflected electrical signal corresponding to the reflected analog signal;

[0108] S213: Perform AND gate shaping on the transmitted and reflected electrical signals to obtain the AND gate output signal;

[0109] S214: Determine whether the output signal of the AND gate matches the transmitted electrical signal.

[0110] S215: Determine that the target has been hit by the emitted light signal.

[0111] S216: Determine that the target was not hit by the emitted light signal.

[0112] In this implementation scenario, if the transmitted electrical signal and the reflected electrical signal are not signals of the same frequency, then steps S210-S216 are basically the same as steps S101-S107 in the first embodiment of the anti-interference method for the reflective photoelectric sensor provided by the present invention, and will not be described again here.

[0113] If the transmitted and reflected electrical signals are at the same frequency, after a preset time, the transmitted electrical signal with an adjusted transmission time interval is acquired. Based on this adjusted transmission time interval, a transmitted optical signal is emitted towards the detection target. Assuming the interference signals are emitted simultaneously, i.e., the positions of the first high-level pulses in the same period T coincide. Since the reflection time interval of the interference signal and the transmission time interval of the transmitted electrical signal are not equal, the reflected electrical signal may include three high-level pulses in one period T. AND gate circuit 28 performs AND gate shaping on the reflected and transmitted electrical signals to obtain the AND gate output signal. The AND gate output signal has two high-level pulses in each period.

[0114] In another implementation scenario, please refer to [the relevant documentation]. Figure 5 , Figure 5 This is a schematic diagram of the signal waveform of the reflective photoelectric sensor provided by the present invention in a third embodiment. If the emitted light signal fails to hit the detection target, the received reflected light signal is an interference signal. It is assumed that the interference signals are emitted simultaneously, meaning that the positions of the first high-level pulses in the same period T coincide. In the reflected electrical signal, one period T may include two high-level pulses. The reflected electrical signal and the emitted electrical signal are ANDed together to obtain the AND gate output signal. The AND gate output signal has only one high-level pulse per period.

[0115] exist Figure 4The output signal of the AND gate matches the transmitted electrical signal; therefore, it can be determined that the target was hit by the transmitted light signal. Figure 5 The output signal of the AND gate and the transmitted electrical signal are mismatched, so it can be determined that the target was not hit by the transmitted light signal.

[0116] In another implementation scenario, please refer to [the relevant documentation]. Figure 6 , Figure 6 This is a schematic diagram of the fourth embodiment of the signal waveform of the reflective photoelectric sensor provided by the present invention. (See diagram below.) Figure 6 As shown, within one period T, the transmitted electrical signal has three high-level pulses. If the transmitted light signal fails to hit the target, the received reflected light signal is an interference signal. Assuming the interference signals are transmitted simultaneously, meaning the positions of the first high-level pulses coincide within the same period T, the reflected electrical signal may contain three high-level pulses within one period T. The reflected electrical signal and the transmitted electrical signal are ANDed together using a gate to obtain the AND gate output signal. The AND gate output signal has only one high-level pulse per period.

[0117] exist Figure 6 The output signal of the AND gate and the transmitted electrical signal are mismatched, so it can be determined that the target was not hit by the transmitted light signal.

[0118] As described above, in this embodiment, the operation of delaying the transmission of the optical signal is delayed by a preset time. Within the preset time, the reflection time interval of the reflected electrical signal caused by the interference signal is obtained. The transmission time interval of the transmitted electrical signal is adjusted according to the reflection time interval. This can avoid the influence of the interference signal on the judgment result of the processing circuit and improve the accuracy and reliability of the detection result judgment.

[0119] Unlike existing technologies, this invention delays the operation of transmitting the optical signal by a preset time. Within this preset time, the reflection time interval of the reflected electrical signal caused by interference signals is obtained. The transmission time interval of the transmitted electrical signal is adjusted according to the reflection time interval. This avoids the influence of interference signals on the judgment results of the processing circuit. The AND gate circuit of the reflective photoelectric sensor performs AND gate shaping on the reflected electrical signal and the transmitted electrical signal, filtering out pulses in the reflected electrical signal that are not formed due to the transmitted optical signal hitting the detection target. The detection result is obtained based on the output signal of the filtered AND gate, which can effectively improve the accuracy of the judgment.

[0120] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A reflective photoelectric sensor, characterized in that, include: Control circuitry used to generate the transmitted electrical signal; A transmitting circuit, connected to the control circuit, is used to transmit an optical signal to the detection target according to the transmitting electrical signal; A receiving circuit is used to receive the reflected light signal reflected by the detection target and generate a simulated reflection signal; A comparator circuit, connected to the receiving circuit, is used to generate a reflected electrical signal corresponding to the reflected analog signal; An AND gate circuit, connected to the control circuit and the comparison circuit, is used to perform AND gate shaping on the transmitted electrical signal and the reflected electrical signal to obtain the AND gate output signal; The processing circuit, connected to the AND gate circuit and the control circuit, is used to obtain the detection result based on the AND gate output signal. If the AND gate output signal matches the transmitted electrical signal, it is determined that the detection target has been hit by the transmitted light signal. A delay circuit, connected to the transmitting circuit, is used to delay the operation of the transmitting circuit in transmitting the transmitted optical signal by a preset time. A detection circuit, connected to the comparison circuit, is used to obtain the reflection time interval of the reflected electrical signal corresponding to the reflected light signal when the receiving circuit receives the reflected light signal; An adjustment circuit, connected to the detection circuit and the control circuit, is used to adjust the transmission time interval of the transmitted electrical signal according to the reflection time interval; A first judgment circuit, connected to the adjustment circuit, is used to determine whether the adjusted transmission time interval is greater than a preset threshold. If the adjusted transmission time interval is greater than the preset threshold, the transmission time interval is readjusted according to the following formula: △T = 2 * |Td1 - Td2| Td1''=Td1-△T Where Td1 is the original transmission time interval, Td2 is the reflection time interval, and Td1'' is the readjusted transmission time interval; The calculation circuit, connected to the first judgment circuit and the control circuit, is used to calculate the preset threshold based on the transmission period and transmission pulse time of the transmitted electrical signal.

2. The reflective photoelectric sensor according to claim 1, characterized in that, The comparison circuit includes: A comparator is provided, wherein the first input terminal of the comparator is connected to the receiving circuit, the terminal of the comparator is connected to a reference level, and the output point of the comparator is connected to the AND gate circuit. The comparator is used to organize the reflected light signal into a square wave form of the reflected electrical signal according to the reference level.

3. The reflective photoelectric sensor according to claim 1, characterized in that, The reflective photoelectric sensor also includes: The second judgment circuit, connected to the comparison circuit, the adjustment circuit, and the control circuit, is used to judge the transmitted electrical signal and the reflected electrical signal. If the transmitted electrical signal and the reflected electrical signal are at the same frequency, then the adjustment circuit is activated.

4. An anti-interference method for a reflective photoelectric sensor, characterized in that, Applied to the reflective photoelectric sensor as described in any one of claims 1-3, comprising: Acquire the transmitted electrical signal, and transmit the transmitted optical signal to the detection target after a preset delay; upon receiving the reflected optical signal, acquire the reflection time interval of the reflected electrical signal corresponding to the reflected optical signal; calculate the preset threshold based on the transmission period and transmission pulse time of the transmitted electrical signal; determine whether the adjusted transmission time interval is greater than the preset threshold; if the adjusted transmission time interval is greater than the preset threshold, readjust the transmission time interval according to the following formula: △T = 2 * |Td1 - Td2| Td1''=Td1-△T Where Td1 is the original transmission time interval, Td2 is the reflection time interval, and Td1'' is the readjusted transmission time interval; Receive the reflected light signal from the target and generate a simulated reflection signal; Generate a reflected electrical signal corresponding to the simulated reflected signal; The transmitted electrical signal and the reflected electrical signal are shaped by an AND gate to obtain the AND gate output signal; Determine whether the AND gate output signal matches the transmitted electrical signal. If the AND gate output signal matches the transmitted electrical signal, then determine that the detection target has been hit by the transmitted light signal.

5. The anti-interference method for the reflective photoelectric sensor according to claim 4, characterized in that, The step of generating the reflected electrical signal corresponding to the reflected analog signal includes: Obtain a reference level, and organize the reflected light signal into a square wave form based on the reference level.

6. The anti-interference method for the reflective photoelectric sensor according to claim 4, characterized in that, Before the step of determining whether the adjusted transmission time interval is greater than a preset threshold, the following steps are included: Determine whether the transmitted electrical signal and the reflected electrical signal are signals of the same frequency. If the transmitted electrical signal and the reflected electrical signal are signals of the same frequency, then perform the step of adjusting the transmission time interval of the transmitted electrical signal according to the reflection time interval.

Images