Optoelectronic sensor and detection device

Abstract

The utility model relates to photoelectric sensing technical field provides a kind of photoelectric sensor and detection device, comprising: first cylinder and second cylinder are arranged on base to form detection passage;The side of first cylinder close to second cylinder is equipped with first notch and second notch along detection direction, and second cylinder is correspondingly equipped with third notch and fourth notch, and the first incident light of emission unit in first cylinder is emitted to reach the receiving unit in second cylinder through first notch and third notch to form first light path, and it emits second incident light to reach receiving unit through second notch and fourth notch to form second light path;Third notch and fourth notch both have the first surface away from base and the second surface close to base, and first surface and second surface present 15 °~20 ° angle of inclusion;Control unit is arranged in base and is connected emission unit, receiving unit. To solve the problem that related art lacks dust penetration and strong anti-interference ability, and can integrate multifunctional photoelectric sensor.

Description

Technical Field

[0001] This utility model relates to the field of photoelectric sensing technology, and in particular to a photoelectric sensor and detection device. Background Technology

[0002] Positioning sensors used at turnstiles and parcel sorting entrances typically employ slot-shaped photoelectric sensors and utilize light guides to alter the propagation direction of emitted and received light. These sensors only transmit the presence or absence of a signal, i.e., they only transmit high or low level signals indicating whether there is an obstruction.

[0003] Specifically, the relevant photoelectric sensors have the following technical defects: the light guide column structure suffers severe light path attenuation in dusty environments, and the penetration is usually less than 5 sheets of A4 paper (about 0.5cm), leading to false triggering, i.e., poor penetration due to dust accumulation; the high-sensitivity photodiode (PD) is easily affected by ambient light or dual-channel crosstalk during the response period, i.e., weak anti-interference ability; and the function is limited, with speed detection and positioning requiring external modules, increasing system cost and complexity.

[0004] There is currently no effective solution to the problem of the lack of a photoelectric sensor with strong dust penetration and anti-interference capabilities that can be integrated with multiple functions in related technologies. Utility Model Content

[0005] The present invention provides a photoelectric sensor and detection device that at least solves the problem in the related art of lacking a photoelectric sensor with strong dust penetration and anti-interference ability, and capable of integrating multiple functions.

[0006] This utility model provides a photoelectric sensor, including a base, a first column, a second column, a transmitting unit, a receiving unit, and a control unit. The first and second columns are disposed on the base, forming a detection channel. The transmitting unit is disposed inside the first column, and the receiving unit is disposed inside the second column. The first column has a first slot and a second slot along a first direction on the side near the second column, and the second column has a third slot and a fourth slot along the first direction on the side near the first column. The transmitting unit emits a first incident light and a second incident light. The first incident light passes through the first and third slots to reach the receiving unit, forming a first optical path, and the second incident light passes through the second and fourth slots to reach the receiving unit, forming a second optical path. The first direction is the direction of detection along the detection channel. The third and fourth slots each have a first surface away from the base and a second surface near the base, with the first surface and the second surface forming an angle of 15° to 20°. The control unit is disposed inside the base and is connected to the transmitting unit and the receiving unit.

[0007] Preferably, the first slot is close to the surface of the base, the second slot is close to the surface of the base, the second surface forms an angle of 25° to 35° with the surface of the base, and the surface of the base is parallel to the first direction.

[0008] Preferably, the dimensions of the first slot, the second slot, the third slot, and the fourth slot along the first direction are all 25mm; the depths of the first slot, the second slot, the third slot, and the fourth slot are all 18mm; and the distance between the first slot and the second slot along the first direction, as well as the distance between the third slot and the fourth slot along the first direction, are all 10mm.

[0009] Preferably, the transmitting unit includes a first light-emitting diode, a second light-emitting diode, and a driving circuit board. The driving circuit board is connected to the control unit. The driving circuit board drives the first light-emitting diode to emit first incident light and drives the second light-emitting diode to emit second incident light. The receiving unit includes a first photodiode, a second photodiode, and a signal amplification circuit board. The first photodiode receives the first incident light, and the second photodiode receives the second incident light. Both the first and second photodiodes are connected to the control unit through the signal amplification circuit board.

[0010] Preferably, the carrier frequency of the first light-emitting diode is set to 4kHz, and the pulse width is set to 2. The carrier frequency of the second LED is set to 4kHz, and the pulse width is set to 3. The time interval between the emission of the first incident light and the second incident light is greater than the cooling period of the first photodiode and the second photodiode.

[0011] Preferably, the control unit includes a control circuit board and an alarm component; the control circuit board is connected to the drive circuit board, the signal amplification circuit board, and the alarm component.

[0012] Preferably, the control circuit board includes a control chip, and the signal amplification circuit board includes a signal amplification circuit and a dynamic threshold comparator; the first photodiode and the second photodiode are both connected to the signal amplification circuit, the signal amplification circuit is connected to the dynamic threshold comparator, and the dynamic threshold comparator is connected to the control chip.

[0013] Preferably, it also includes a housing, which covers the surfaces of the base, the first column, and the second column, and the housing is made of acrylonitrile-butadiene-styrene copolymer with added flame retardant.

[0014] Preferably, the surfaces of the first slot, the second slot, the third slot, and the fourth slot are all covered with a black coating with a reflectivity of less than 5%.

[0015] The present invention provides a detection device including a support member and any of the above-mentioned photoelectric sensors, wherein the support member is connected to the photoelectric sensor.

[0016] This utility model provides a photoelectric sensor and detection device. A first column and a second column are mounted on a base to form a detection channel. The first column has a first slot and a second slot along the detection direction on the side near the second column. The second column has corresponding third and fourth slots. A transmitting unit in the first column emits first incident light, which passes through the first and third slots to reach a receiving unit in the second column, forming a first optical path. It also emits second incident light, which passes through the second and fourth slots to reach the receiving unit, forming a second optical path. Both the third and fourth slots have a first surface away from the base and a second surface near the base, with the first and second surfaces forming an angle of 15° to 20°. A control unit is mounted inside the base and connected to the transmitting and receiving units. This sensor exhibits strong dust penetration and anti-interference capabilities, facilitating multi-functional integration. It addresses the lack of a photoelectric sensor in related technologies that possesses strong dust penetration and anti-interference capabilities and can be integrated with multiple functions. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the structure of a photoelectric sensor observed along a first direction in an embodiment of this utility model.

[0018] Figure 2 This is a schematic diagram of the side of the first column 2 close to the second column 3 in an embodiment of this utility model.

[0019] Figure 3 This is a schematic diagram of the side of the second column 3 close to the first column 2 in an embodiment of this utility model.

[0020] The above figures include the following reference numerals: 1. Base; 2. First column; 3. Second column; 4. Transmitting unit; 5. Receiving unit; 6. Control unit; 21. First slot; 22. Second slot; 31. Third slot; 32. Fourth slot; X: First direction; α: The angle between the first surface and the second surface; β: Angle between the second surface and the base. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0024] Positioning sensors used at turnstiles and parcel sorting entrances typically employ slot-shaped photoelectric sensors with light guides to alter the propagation direction of emitted and received light. These sensors only transmit the presence or absence of a signal, i.e., they only transmit high and low level signals indicating whether there is obstruction. This results in the following technical drawbacks: the light guide structure suffers severe light path attenuation in dusty environments, with penetration typically less than 0.5cm (about 5 sheets of A4 paper), leading to false triggering (poor penetration due to dust accumulation); the high-sensitivity photodiode (PD) is easily affected by ambient light or dual-channel crosstalk during its response period, indicating weak anti-interference capabilities; and its limited functionality requires external modules for speed detection and positioning, increasing system cost and complexity.

[0025] Therefore, this utility model provides a photoelectric sensor and detection device, which has strong dust penetration and anti-interference capabilities, and can integrate multiple functions.

[0026] Firstly, please refer to Figures 1 to 3 As shown, this utility model embodiment provides a photoelectric sensor, including a base 1, a first column 2, a second column 3, a transmitting unit 4, a receiving unit 5, and a control unit 6.

[0027] The first column 2 and the second column 3 are mounted on the base 1, forming a detection channel. During detection, the target object will pass through the first optical path and the second optical path sequentially. The first column 2, the base 1, and the second column 3 can be integrally formed or assembled from parts.

[0028] The transmitting unit 4 is disposed inside the first column 2, and the receiving unit 5 is disposed inside the second column 3. The first column 2 has a first slot 21 and a second slot 22 along the first direction X on the side close to the second column 3. The second column 3 has a third slot 31 and a fourth slot 32 along the first direction X on the side close to the first column 2. The transmitting unit 4 emits a first incident light and a second incident light. The first incident light passes through the first slot 21 and the third slot 31 to reach the receiving unit 5, forming a first optical path. The second incident light passes through the second slot 22 and the fourth slot 32 to reach the receiving unit 5, forming a second optical path. The first direction X is the direction of detection along the detection channel.

[0029] Figure 1 The first optical path is indicated by a black dashed line and an arrow. Because... Figure 1 This is a schematic diagram of the above-mentioned photoelectric sensor structure as observed along the first direction X. The second optical path is... Figure 1 The middle overlaps with the first optical path, and the second slot 22 is in Figure 1 The middle overlaps with the first slot 21, and the fourth slot 32 is in Figure 1 The second slot 22 and the fourth slot 32 do not overlap with the third slot 31, so the second slot 22 and the fourth slot 32 are not in the same position as the second optical path. Figure 1 As shown in the image.

[0030] Both the third slot 31 and the fourth slot 32 have a first surface away from the base and a second surface close to the base 1, with the first surface and the second surface forming an angle of 15° to 20°. Figure 1 In this context, α represents the angle between the first surface and the second surface. The angle α can be, but is not limited to, 15°, 16°, 17°, 18°, 19°, and 20°.

[0031] The control unit 6 is located inside the base 1 and is connected to the transmitting unit 4 and the receiving unit 5. The control unit 6 controls the transmitting unit 4 to emit the first incident light and the second incident light, and performs corresponding control based on the signals transmitted by the receiving unit 5.

[0032] Specifically, the photoelectric sensor formed by the detection channel based on the first column 2, the base 1, and the second column 3 is a slot-type photoelectric sensor, which can be applied to gate openings and package sorting entrances. Unlike slot-type photoelectric sensors in related technologies, the photoelectric sensor provided in this embodiment does not require a light guide column and adopts a direct-light path design. By setting an included angle α, the structure of the third slot 31 and the fourth slot 32 is designed as a V-shaped light trap structure. Furthermore, the transmitting unit 4, the receiving unit 5, and the control unit 6 are all equipped with independent printed circuit boards (PCBs), enabling speed detection and positioning functions while resisting dust interference.

[0033] Furthermore, by simultaneously setting angles α and β, the infrared light emitted directly from the transmitting unit 4 can be guided, allowing the light to be more concentrated towards the receiving unit 5, thereby improving signal strength and penetration. This embodiment will be further explained later.

[0034] In summary, the photoelectric sensor provided by the present invention can solve the problem in the related technology of lacking a photoelectric sensor with strong dust penetration and anti-interference ability, and capable of integrating multiple functions.

[0035] Preferably, the photoelectric sensor provided in this embodiment further includes a housing, which covers the surfaces of the base 1, the first column 2, and the second column 3. The housing is made of acrylonitrile-butadiene-styrene copolymer with added flame retardant.

[0036] It should be noted that the first slot 21 and the second slot 22 opened on the first column 2, as well as the third slot 31 and the fourth slot 32 opened on the second column 3, are not covered by the shell.

[0037] Acrylonitrile-butadiene-styrene copolymer with added flame retardants, i.e. flame-retardant ABS material, can achieve an IP67 protection rating.

[0038] Preferably, the first slot is close to the surface of the base, the second slot is close to the surface of the base, the second surface forms an angle of 25° to 35° with the surface of the base, and the surface of the base is parallel to the first direction. Figure 1 The included angle shown by β is 25°~35°, for example 25°, 30°, 35°.

[0039] At this point, the first slot 21 is close to the surface of the base 1, the second slot 22 is close to the surface of the base 1, and the second surface is a slope. By laser etching micro-textures on the aforementioned slope, stray light from the outside can be scattered.

[0040] Specifically, the V-shaped light trap structure and micro-texture form a multiple scattering cross-section. Ambient light, such as industrial spotlights or natural light, enters the slot of the aforementioned photoelectric sensor and is repeatedly scattered and consumed, unable to directly reach or be reflected to the receiving unit 5. Combined with a direct-light path design, this effectively improves signal strength and penetration. The aforementioned slots are collectively referred to as the first slot 21, the second slot 22, the third slot 31, and the fourth slot 32.

[0041] Preferably, the surfaces of the first slot 21, the second slot 22, the third slot 31, and the fourth slot 32 are all covered with a black coating with a reflectivity of less than 5% to achieve an anti-reflective effect.

[0042] The black coating reduces reflectivity, while the V-shaped light trap structure and micro-texture enhance the scattering effect. The combination of these two elements achieves dual stray light suppression with low reflection and strong scattering, resulting in stronger anti-interference capabilities than using a single structure.

[0043] The overall dimensions of the photoelectric sensor provided in this embodiment can be designed to be 40mm in length, 20mm in width, and 30mm in height. Preferably, the dimensions of the first slot 21, the second slot 22, the third slot 31, and the fourth slot 32 along the first direction X are all 25mm; the depths of the first slot 21, the second slot 22, the third slot 31, and the fourth slot 32 are all 18mm; and the distance between the first slot 21 and the second slot 22 along the first direction X, and the distance between the third slot 31 and the fourth slot 32 along the first direction X, are all 10mm.

[0044] The aforementioned spacing of 10mm is set in order to physically isolate the adjacent first slot 21 and second slot 22, and the adjacent third slot 31 and fourth slot 32, thereby reducing crosstalk to a certain extent.

[0045] Preferably, the emitting unit 4 includes a first light-emitting diode, a second light-emitting diode, and a driving circuit board. The driving circuit board is connected to the control unit 6. The driving circuit board drives the first light-emitting diode to emit a first incident light and drives the second light-emitting diode to emit a second incident light. The driving method of the driving circuit board can be, but is not limited to, PWM wave driving. The driving circuit board can also incorporate a short-circuit protection circuit with a response time of less than 1μs and electromagnetic compatibility (EMC) protection design.

[0046] The receiving unit 5 includes a first photodiode, a second photodiode, and a signal amplification circuit board. The first photodiode receives the first incident light, and the second photodiode receives the second incident light. Both the first and second photodiodes are connected to the control unit 6 through the signal amplification circuit board.

[0047] The first and second light-emitting diodes can be, but are not limited to, infrared emitting light-emitting diodes (abbreviated as infrared emitting tubes or infrared emitting diodes).

[0048] Both the first and second photodiodes are high-sensitivity photodiodes, such as PIN photodiodes and avalanche photodiodes.

[0049] Furthermore, the carrier frequency of the first light-emitting diode is set to 4kHz, and the pulse width is set to 2. The carrier frequency of the second LED is set to 4kHz, and the pulse width is set to 3. The time interval between the emission of the first incident light and the second incident light is greater than the cooling period of the first photodiode and the second photodiode.

[0050] High-sensitivity photodiodes are susceptible to interference from ambient light or dual-channel crosstalk during their cooling period (also known as the response period). Setting the emission time interval between the first and second incident light to be longer than the cooling period of the first and second photodiodes can mitigate this interference and suppress crosstalk.

[0051] For example, the cooling period of the first photodiode and the second photodiode is 110 μs, and the emission time interval between the first incident light and the second incident light is set to 125 μs.

[0052] Preferably, the control unit 6 includes a control circuit board and an alarm component; the control circuit board is connected to the drive circuit board, the signal amplification circuit board, and the alarm component.

[0053] In the event of extreme interference, the control circuit board can control the alarm component to issue an alarm signal. Extreme interference can be, but is not limited to, repeated interference; please refer to the following description for details.

[0054] Furthermore, the control circuit board includes a control chip, and the signal amplification circuit board includes a signal amplification circuit and a dynamic threshold comparator; the first photodiode and the second photodiode are both connected to the signal amplification circuit, the signal amplification circuit is connected to the dynamic threshold comparator, and the dynamic threshold comparator is connected to the control chip.

[0055] The gain of the signal amplifier circuit can be set to 30dB.

[0056] The dynamic threshold of the dynamic threshold comparator can be adjusted by feedback control of the signal pulse width intensity.

[0057] Specifically, the power supply of the aforementioned photoelectric sensor can adopt a wide voltage input of DC 12-24V, and has built-in reverse connection protection and overvoltage protection.

[0058] In addition, this embodiment also provides the detection logic for some of the functions of the above-mentioned photoelectric sensor, as shown below.

[0059] Speed ​​detection is performed based on the aforementioned photoelectric sensor. ; In the formula, Indicates the detection speed. This indicates the distance between the first slot 21 and the second slot 22 (or the distance between the third slot 31 and the fourth slot 32), for example, 10mm. This represents the trigger time difference between the two signals, that is, the time interval between the emission of the first incident light and the second incident light. This indicates the channel spacing compensation amount (needs to be calibrated; the ideal value is 0).

[0060] Positioning is determined based on the aforementioned photoelectric sensor: the target first passes through the first optical path, causing the receiving unit to transmit a corresponding signal, and the target moves in the forward direction; the target first passes through the second optical path, causing the receiving unit to transmit a corresponding signal, and the target moves in the reverse direction.

[0061] Based on the aforementioned photoelectric sensor, a two-stage speed control is implemented: The target first passes through the first optical path, and the receiving unit 5 outputs a PWM signal (e.g., a signal with a 30% duty cycle) to the control unit 6, which then controls the transmission device to decelerate. The target then passes through the second optical path, and the receiving unit 5 outputs a switching signal to the control unit 6, which issues a stop command, causing the transmission device to stop. If the first and second optical paths are continuously blocked for more than a preset time (e.g., 1 second), the receiving unit 5 outputs a fault alarm signal to the control unit 6, which then triggers an alarm. The transmission device, which transports the target along the detection channel, is existing technology and will not be described further in this embodiment.

[0062] Furthermore, based on the structural design of the photoelectric sensor provided in this embodiment, the following anti-interference design can be implemented.

[0063] Signal acquisition: After the transmitting unit 4 transmits the first incident light and the second incident light, the time window is opened: Channel 1 (first optical path) is set to 5μs, and Channel 2 (second optical path) is set to 8μs. The receiving unit 5 only acquires the corresponding PD signal within the corresponding time window.

[0064] Five-level verification is performed: 1) Coding verification: detecting the signal frequency (with a frequency tolerance less than ±50Hz) and the obtained signal pulse width (with a tolerance of ±0.5μs). 2) Energy threshold decision: the signal pulse width shall meet the requirements: Channel 1: 3us < Signal1 < 4us; Channel 2: 5us < Signal2 < 6us. The threshold of the pre-stage comparator can be feedback-adjusted based on the simultaneously acquired pulse widths of the two channels of signals. 3) Mutual interference suppression: the transmission interval between the two channels is 125μs, which ensures crossing the 110μs cooling period of the PD. 4) Autonomous period offset: comparator signal judgment is performed at the front and rear ends close to the detection window. When an effective level is judged, the transmission and reception period will be offset autonomously. If the front end detects the effective level, the period will be offset backward by a value (the specific value can be obtained by collecting external noise through an analog-to-digital converter ADC as a random number seed, and is not a fixed value); if the rear end detects the effective level, the period will be offset forward; if effective levels are detected at both the front end and the rear end, the period is offset by T / 2 (T represents a complete working cycle of the photoelectric sensor for transmitting light and receiving light). If effective levels are still continuously detected at the front end or the rear end after multiple (e.g., 5 consecutive) offsets, an alarm is sent out to indicate that an extreme situation is encountered. 5) Extreme interference detection: signal detection is also performed outside the detection window. When a periodic signal with a pulse width close to that of the own effective signal is detected outside the detection window and there is an effective signal inside the detection window, multiple rechecking detections are performed after each 11us period offset. If this situation occurs continuously (for example, 8 consecutive times), an alarm is sent out that a dense frequency-doubled interference signal of the product's own frequency is encountered.

[0065] Virtual signal reconstruction: after the PD is triggered, a 110μs high level is forcibly output after an interval (for example, 20us, which reserves detection space for period offset and extreme interference detection), to simulate the continuous blocking state, and it will automatically reset after the cooling period ends. This function is used to suppress the loss of subsequent normal signals caused by the advance triggering of the PD by interference signals to a certain extent.

[0066] Based on the above content, a dual-channel pulse code modulation driving and adaptive receiving circuit is designed, which can enhance the anti-ambient light interference performance. By combining five-level verification and virtual signal reconstruction, the delayed response problem of the photodiode can be solved, and the functions of speed detection, positioning judgment and two-stage speed control can be better realized.

[0067] In practical applications, the virtual signal reconstruction function and the extreme interference detection function are mutually exclusive, and only one of them can be selected in a specific product, which can be enabled according to requirements.

[0068] This embodiment also provides the performance data of the above photoelectric sensor herein, which is specifically shown as follows.

[0069] Penetrability: The detection function works normally after actually penetrating 20 sheets of A4 paper (about 2.0 cm).

[0070] Interference resistance: Zero false triggering under direct 100,000 lux spotlight white light.

[0071] Response performance: 1) Signal delay: 125μs (including virtual reconstruction compensation); 2) Velocity detection: Theoretically, a velocity of 80m / s can be detected.

[0072] Reliability: Passed EMC Level 4 test.

[0073] Secondly, this embodiment of the invention also provides a detection device, which includes the aforementioned photoelectric sensor. Therefore, this detection device encompasses all the technical effects of the aforementioned photoelectric sensor. Since the technical effects of the photoelectric sensor have already been described in detail above, they will not be repeated here. Simultaneously, the aforementioned detection device also includes a support member, which is connected to the aforementioned photoelectric sensor and serves a supporting function.

[0074] Those skilled in the art can add functional modules to the above-mentioned detection device to achieve functions that the above-mentioned photoelectric sensor does not have. The embodiments of this utility model will not be described in detail here.

[0075] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0076] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0077] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A photoelectric sensor, characterized in that, It includes a base, a first column, a second column, a transmitting unit, a receiving unit, and a control unit; The first column and the second column are disposed on the base, and the first column, the base and the second column form a detection channel; The transmitting unit is disposed inside the first column, and the receiving unit is disposed inside the second column. The first column has a first slot and a second slot along a first direction on the side near the second column, and the second column has a third slot and a fourth slot along the first direction on the side near the first column. The transmitting unit emits a first incident light and a second incident light. The first incident light passes through the first slot and the third slot to reach the receiving unit, forming a first optical path. The second incident light passes through the second slot and the fourth slot to reach the receiving unit, forming a second optical path. The first direction is the direction of detection along the detection channel. Both the third slot and the fourth slot have a first surface away from the base and a second surface close to the base, with the first surface and the second surface forming an angle of 15° to 20°. The control unit is located inside the base and is connected to the transmitting unit and the receiving unit.

2. The photoelectric sensor according to claim 1, characterized in that, The first slot is close to the surface of the base, the second slot is close to the surface of the base, the second surface forms an angle of 25° to 35° with the surface of the base, and the surface of the base is parallel to the first direction.

3. The photoelectric sensor according to claim 1, characterized in that, The dimensions of the first slot, the second slot, the third slot, and the fourth slot along the first direction are all 25mm; The depths of the first slot, the second slot, the third slot, and the fourth slot are all 18 mm; The distance between the first slot and the second slot along the first direction, and the distance between the third slot and the fourth slot along the first direction, are both 10 mm.

4. The photoelectric sensor according to claim 1, characterized in that, The emitting unit includes a first light-emitting diode, a second light-emitting diode, and a driving circuit board. The driving circuit board is connected to the control unit. The driving circuit board drives the first light-emitting diode to emit the first incident light and drives the second light-emitting diode to emit the second incident light. The receiving unit includes a first photodiode, a second photodiode, and a signal amplification circuit board. The first photodiode receives the first incident light, and the second photodiode receives the second incident light. Both the first photodiode and the second photodiode are connected to the control unit through the signal amplification circuit board.

5. The photoelectric sensor according to claim 4, characterized in that, The carrier frequency of the first light-emitting diode is set to 4kHz, and the pulse width is set to 2. The carrier frequency of the second light-emitting diode is set to 4kHz, and the pulse width is set to 3. ; The time interval between the emission of the first incident light and the second incident light is greater than the cooling period of the first photodiode and the second photodiode.

6. The photoelectric sensor according to claim 4, characterized in that, The control unit includes a control circuit board and an alarm component; The control circuit board is connected to the drive circuit board, the signal amplification circuit board, and the alarm component.

7. The photoelectric sensor according to claim 6, characterized in that, The control circuit board includes a control chip, and the signal amplification circuit board includes a signal amplification circuit and a dynamic threshold comparator. Both the first photodiode and the second photodiode are connected to the signal amplification circuit, which is connected to the dynamic threshold comparator, which is connected to the control chip.

8. The photoelectric sensor according to claim 1, characterized in that, It also includes a housing that covers the surfaces of the base, the first column and the second column, and the housing is made of acrylonitrile-butadiene-styrene copolymer with added flame retardant.

9. The photoelectric sensor according to claim 1, characterized in that, The surfaces of the first slot, the second slot, the third slot, and the fourth slot are all covered with a black coating with a reflectivity of less than 5%.

10. A detection device, characterized in that, It includes a support member and a photoelectric sensor according to any one of claims 1 to 9, wherein the support member is connected to the photoelectric sensor.

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