A retroreflective photoelectric sensor and electronic device

Abstract

This invention discloses a retroreflection photoelectric sensor and electronic device, belonging to the field of sensor technology. It includes a transmitter assembly for emitting a detection beam, a receiver assembly for receiving the detection beam after retroreflection by a reflector, a front cover disposed between the transmitter assembly and the reflector for the light exit path, and between the receiver assembly and the reflector for the light entrance path, and a first polarizing film and a second polarizing film respectively attached to the outer surface of the front cover. The first polarizing film covers the light exit port of the light exit path, and the second polarizing film covers the light entrance port of the light entrance path, with the polarization directions of the first and second polarizing films perpendicular to each other. This invention achieves the technical effect of avoiding the adverse effects of residual stress inside the front cover on the polarization direction of linearly polarized light, thus improving the detection accuracy and stability of the sensor.

Description

Technical Field

[0001] This utility model belongs to the field of sensor technology, and specifically relates to a retroreflective photoelectric sensor and electronic device. Background Technology

[0002] Retroreflective photoelectric sensors are widely used in industrial automation, logistics sorting, and security protection. They work by emitting a light beam from a transmitter onto a reflector, which reflects the beam back to the receiver. When the receiver continuously receives the light signal, the sensor is in a stable state. When an object enters the optical path and blocks the light, the reflected light is blocked, the receiver detects the change in the light signal, and triggers an output switch control signal to determine the presence or absence of the object. In existing technologies, the emitted light typically passes through a lens, then a polarizer to become linearly polarized, before exiting through a cover and being reflected by a reflective object on the opposite side before entering the receiving component. However, during the injection molding process, due to uneven material cooling and shrinkage, as well as mold structure, residual stress inevitably forms inside the cover. This residual stress leads to optical anisotropy in the cover material, altering the polarization direction of the linearly polarized light passing through it, causing polarization distortion. This reduces the sensor's ability to suppress non-target reflected light, affecting the sensor's detection accuracy and stability.

[0003] Therefore, it is necessary to provide a new technical solution to solve the above-mentioned technical problems. Utility Model Content

[0004] The technical problem to be solved by this invention is that the residual stress inside the front cover has an adverse effect on the polarization direction of linearly polarized light, resulting in poor detection accuracy and stability of the sensor.

[0005] To solve the above-mentioned technical problems, this utility model provides a retroreflection photoelectric sensor. The retroreflection photoelectric sensor includes a transmitter assembly for emitting a detection beam, a receiver assembly for receiving the detection beam after retroreflection by a reflector, a front cover disposed between the transmitter assembly and the reflector for the light output path and between the receiver assembly and the reflector for the light input path, and a first polarizing film and a second polarizing film respectively attached to the outer surface of the front cover. The first polarizing film covers the light output port of the light output path, and the second polarizing film covers the light input port of the light input path. The polarization directions of the first polarizing film and the second polarizing film are perpendicular to each other.

[0006] Optionally, the transmitter assembly includes a transmitter tube and a transmitter lens, with the front cover located between the first polarizing film and the transmitter lens.

[0007] Optionally, the receiver assembly includes a receiver tube and a receiver lens, with the front cover located between the second polarizing film and the receiver lens.

[0008] Optionally, the front cover is made of injection-molded acrylic material.

[0009] Optionally, the perpendicularity error of the polarization axes of the first polarizing film and the second polarizing film does not exceed 0.1 degrees.

[0010] Optionally, the first polarizing film and the second polarizing film are respectively bonded to the outer surface of the front cover using an optically transparent adhesive.

[0011] Optionally, both the first polarizing film and the second polarizing film have a scratch-resistant hard coating on the side opposite to the outer surface of the front cover.

[0012] Optionally, the reflector includes a plurality of three-sided right-angled prisms.

[0013] Optionally, a plurality of the three right-angled prisms are arranged in a matrix array, with the right-angled vertices of the three right-angled prisms facing one side of the front cover, and the corresponding right-angled edges of adjacent three right-angled prisms being adjacent to each other, so as to continuously form a retroreflective surface in the reflector area.

[0014] According to another aspect of the present invention, the present invention also provides an electronic device, the electronic device including the retroreflective photoelectric sensor, the retroreflective photoelectric sensor being connected to the execution body to realize control of the corresponding function of the execution body.

[0015] Beneficial effects:

[0016] This invention provides a retroreflective photoelectric sensor. A transmitter assembly emits a detection beam, and a receiver assembly receives the beam after retroreflection by a reflector. A front cover is positioned between the transmitter assembly and the reflector in the light exit path and between the receiver assembly and the reflector in the light entrance path. A first polarizing film and a second polarizing film are respectively attached to the outer surface of the front cover. The first polarizing film covers the light exit port of the light exit path, and the second polarizing film covers the light entrance port of the light entrance path. The polarization directions of the first and second polarizing films are perpendicular to each other. Thus, when the detection beam emitted by the transmitter assembly passes through the front cover and then through the first polarizing film, the beam is converted into linearly polarized light with a specific polarization direction. This polarization is unaffected by residual stress within the front cover, maintaining the unchanged polarization direction of the linearly polarized light. Linearly polarized light, after retroreflection by the reflector, passes through the second polarizing film and enters the receiving assembly via the front cover. Because the polarization directions of the first and second polarizing films are perpendicular, only light whose polarization direction has changed after reflection by the reflector can pass through the second polarizing film. This helps suppress interference to the receiving assembly, filters out stray and interfering light, and improves the sensor's detection accuracy and stability. This achieves the technical effect of avoiding the adverse effects of residual stress inside the front cover on the polarization direction of linearly polarized light, thus improving the sensor's detection accuracy and stability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a retroreflective photoelectric sensor provided in an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the structure of the transmitter assembly, receiver assembly, front cover, first polarizing film, and second polarizing film in a retroreflective photoelectric sensor provided in an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0021] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0022] To enable those skilled in the art to better understand the solutions of this application, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0023] In the embodiments of this application, "at least one" refers to one or more; "multiple" refers to two or more. In the description of this application, the terms "first," "second," "third," etc., are used only for the purpose of distinguishing descriptions and should not be construed as indicating or implying relative importance, nor should they be construed as indicating or implying order.

[0024] In this specification, references such as "one embodiment" or "some embodiments" mean that one or more embodiments of this application include the specific features, structures, or characteristics described in connection with that embodiment. Therefore, the terms "comprising," "including," "having," and variations thereof in this specification all mean "including but not limited to," unless otherwise specifically emphasized. It should be noted that in the embodiments of this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone.

[0025] It should be noted that, in the embodiments of this utility model, when a component is referred to as being "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. When a component is considered to be "set on" another component, it can be directly set on the other component or there may be an intervening component. Furthermore, in the embodiments of this application, "connection" can also be understood as an electrical connection; the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components. The terms "vertical," "horizontal," "left," "right," and similar expressions used in the embodiments of this utility model are for illustrative purposes only and are not intended to limit the utility model.

[0026] This utility model provides a retroreflective photoelectric sensor, please refer to [link to relevant documentation]. Figures 1 to 2 As shown, Figure 1 This is a schematic diagram of the structure of a retroreflective photoelectric sensor provided in an embodiment of this utility model. Figure 2 This is a schematic diagram of the structure of a retroreflective photoelectric sensor provided in this embodiment of the present invention, comprising a transmitter assembly, a receiver assembly, a front cover, a first polarizing film, and a second polarizing film. The retroreflective photoelectric sensor provided in this embodiment of the present invention includes a transmitter assembly 1, a receiver assembly 2, a front cover 3, a first polarizing film 4, a second polarizing film 5, and a reflector 6. The transmitter assembly 1 emits a detection beam, and the receiver assembly 2 receives the detection beam after retroreflection by the reflector 6. The front cover 3 is disposed in the light exit path between the transmitter assembly 1 and the reflector 6, and in the light entrance path between the receiver assembly 2 and the reflector 6. The first polarizing film 4 and the second polarizing film 5 are respectively attached to the outer surface of the front cover 3. The first polarizing film 4 covers the light exit port of the light exit path, and the second polarizing film 5 covers the light entrance port of the light entrance path, with the polarization directions of the first polarizing film 4 and the second polarizing film 5 perpendicular to each other.

[0027] The transmitter assembly 1 emits a detection beam. The transmitter assembly 1 may include a light source element such as a light-emitting diode or a laser diode. The transmitter assembly 1 can be installed inside the sensor body and emits the detection beam outward through the light-emitting path of the front cover 3. The receiver assembly 2 receives the detection beam after it has been reflected back by the reflector 6. The receiver assembly 2 may include a photodiode or a photoresistor, and can also be installed inside the sensor body and receive the reflected beam through the light-incident path of the front cover 3.

[0028] The front cover 3 is positioned at the light exit path between the emitting component 1 and the reflector 6, and at the light entrance path between the receiving component 2 and the reflector 6. The front cover 3 protects the internal components of the sensor while allowing the light beam to pass through. A first polarizing film 4 is attached to the outer surface of the front cover 3, covering the light exit port of the light exit path. A second polarizing film 5 is also attached to the outer surface of the front cover 3, covering the light entrance port of the light entrance path. The polarization directions of the first polarizing film 4 and the second polarizing film 5 are perpendicular to each other, forming a cross-polarization structure. The reflector 6 is positioned in the detection area of ​​the sensor. The reflector 6 reflects the detection light beam emitted by the emitting component 1 and passing through the first polarizing film 4 back to the receiving component 2.

[0029] In this process, the detection beam emitted by the transmitting component 1 first passes through the front cover 3 and then through the first polarizing film 4 attached to the outer surface of the front cover 3. At this point, the detection beam is converted into linearly polarized light with a specific polarization direction by the first polarizing film 4. The linearly polarized light continues to propagate to the reflector 6 and is reflected back by the reflector 6. The reflected light then reaches the second polarizing film 5 attached to the outer surface of the front cover 3. Since the polarization directions of the first polarizing film 4 and the second polarizing film 5 are perpendicular to each other, only light that has been reflected by the reflector 6 and whose polarization direction has changed appropriately can pass through the second polarizing film 5. After passing through the second polarizing film 5, it passes through the front cover 3 and enters the receiving component 2 for detection. Stray light in the environment or interference light that has not been reflected by the reflector 6 will be filtered out by the second polarizing film 5 because its polarization direction does not meet the requirements, thereby improving the signal-to-noise ratio and detection accuracy of the sensor.

[0030] In this embodiment, a probe beam is emitted by the transmitting component 1, and the receiving component 2 receives the probe beam after retroreflection by the reflector 6. The front cover 3 is disposed in the light exit path between the transmitting component 1 and the reflector 6, and in the light entrance path between the receiving component 2 and the reflector 6. A first polarizing film 4 and a second polarizing film 5 are respectively attached to the outer surface of the front cover 3. The first polarizing film 4 covers the light exit port of the light exit path, and the second polarizing film 5 covers the light entrance port of the light entrance path. The polarization directions of the first polarizing film 4 and the second polarizing film 5 are perpendicular to each other. Thus, when the probe beam emitted by the transmitting component 1 passes through the front cover 3 and then through the first polarizing film 4, the probe beam is converted into linearly polarized light with a specific polarization direction. It is not affected by the internal residual stress of the front cover 3, and the polarization direction of the linearly polarized light remains unchanged. Linearly polarized light, after retroreflection by reflector 6, passes through the second polarizing film 5 and then through the front cover 3 into the receiving assembly 2. Since the polarization directions of the first polarizing film 4 and the second polarizing film 5 are perpendicular, only light whose polarization direction has changed after reflection by reflector 6 can pass through the second polarizing film 5. This helps suppress interference to the receiving assembly 2, filters out stray and interfering light, and improves the sensor's detection accuracy and stability. This achieves the technical effect of avoiding the adverse effects of residual stress inside the front cover 3 on the polarization direction of linearly polarized light, thus improving the sensor's detection accuracy and stability.

[0031] As one embodiment, the retroreflective photoelectric sensor 72 provided by this utility model includes an emitting tube 11 and an emitting lens 12. The front cover 3 is located between the first polarizing film 4 and the emitting lens 12. First, a light beam can be generated through the emitting tube 11, then focused and collimated by the emitting lens 12, and then converted into linearly polarized light with a specific polarization direction after passing through the front cover 3 and the first polarizing film 4. The front cover 3 is located between the first polarizing film 4 and the emitting lens 12, which can protect the emitting lens 12 from the influence of the external environment and extend its service life. At the same time, since the first polarizing film 4 is located on the outer surface of the front cover 3, the detection light beam passes through the first polarizing film 4 only after passing through the front cover 3, which can avoid the disturbance of the polarized light by the internal residual stress of the front cover 3, so that the output linearly polarized light has a stable polarization direction, which can improve the detection accuracy and stability of the sensor.

[0032] In some embodiments, the receiving end component 2 of the retroreflection photoelectric sensor 72 provided by this utility model includes a receiving tube 21 and a receiving lens 22. The front cover 3 is located between the second polarizing film 5 and the receiving lens 22. The light beam reflected by the reflector 6 first passes through the second polarizing film 5 and then through the front cover 3. It is then collected and focused by the receiving lens 22 and then projected onto the photosensitive surface of the receiving tube 21 for detection. The front cover 3 is located between the second polarizing film 5 and the receiving lens 22, which can protect the receiving lens 22 from the influence of the external environment and extend its service life. At the same time, since the second polarizing film 5 is located on the outer surface of the front cover 3, the retroreflected light beam passes through the second polarizing film 5 before passing through the front cover 3, which can also filter out stray light and interference light, allowing only light whose polarization direction matches that of the second polarizing film 5 to pass through, thereby improving the signal-to-noise ratio and detection accuracy of the sensor.

[0033] In some embodiments, the front cover 3 is made of injection-molded acrylic material, specifically polymethyl methacrylate (PMMA) with excellent optical properties. Manufacturing the acrylic front cover 3 using injection molding allows for integrated molding of complex shapes, improving production efficiency and reducing manufacturing costs. The first polarizing film 4 and the second polarizing film 5 are respectively attached to the outer surface of the front cover 3, covering the light exit port of the light-emitting path and the light entrance port of the light-incident path. This ensures that the probe beam emitted by the transmitting component 1 is converted into linearly polarized light only after passing through the front cover 3 and then through the first polarizing film 4, thus avoiding the influence of residual stress within the front cover 3.

[0034] In some embodiments, the perpendicularity error of the polarization axes of the first polarizing film 4 and the second polarizing film 5 does not exceed 0.1 degrees. By controlling the perpendicularity error of the polarization axes of the first polarizing film 4 and the second polarizing film 5 to not exceed 0.1 degrees, the polarization directions of the first polarizing film 4 and the second polarizing film 5 are constrained to be perpendicular. At the same time, the perpendicularity control also ensures that only light that has undergone retroreflection by the reflector 6 and whose polarization direction has been appropriately changed can pass through the second polarizing film 5, while stray light from the environment or interference light that has not been reflected by the reflector 6 is effectively filtered out. When the perpendicularity error of the polarization axes of the first polarizing film 4 and the second polarizing film 5 does not exceed 0.1 degrees, an extremely high extinction ratio can be achieved. That is, without the reflector 6, the light emitted by the transmitting end component 1 is almost completely blocked by the second polarizing film 5, and the signal received by the receiving end component 2 is extremely small. When the reflector 6 enters the detection area, the reflected light can pass through the second polarization film 5 due to the change in polarization direction. The signal received by the receiving end component 2 will be greatly enhanced, realizing reliable target detection. This is beneficial to improving the signal-to-noise ratio and detection accuracy of the sensor, enhancing anti-interference ability, and enabling the sensor to achieve stable and reliable working performance in complex environments.

[0035] In some embodiments, the first polarizing film 4 and the second polarizing film 5 are respectively bonded to the outer surface of the front cover 3 using an optically transparent adhesive. For example, an optically transparent adhesive with high transmittance, low scattering, and low absorption is used to ensure bonding strength while minimizing the impact on light transmission. The tight bonding of the first polarizing film 4 and the second polarizing film 5 to the outer surface of the front cover 3 using the optically transparent adhesive avoids the presence of air layers, reduces light reflection and scattering at different media interfaces, and improves light transmittance. Simultaneously, the optically transparent adhesive can fill the tiny gaps between the polarizing film and the surface of the front cover 3, eliminating bubbles and impurities that may cause light scattering, thereby improving optical performance. Furthermore, it maintains bonding strength and optical performance under various environmental conditions, ensuring long-term stable bonding between the polarizing film and the front cover 3, which is beneficial for extending the sensor's lifespan. In other words, by using an optically transparent adhesive to bond the first polarizing film 4 and the second polarizing film 5 to the outer surface of the front cover 3, not only is light transmittance improved and light energy loss reduced, but the bonding strength between the polarizing film and the front cover 3 is also enhanced, improving the sensor's stability and environmental adaptability.

[0036] In some embodiments, the first polarizing film 4 and the second polarizing film 5 are both provided with a scratch-resistant hard coating on the side opposite to the outer surface of the front cover 3. For example, a scratch-resistant hard coating with high hardness, high light transmittance and good wear resistance can be used. The scratch-resistant hard coating can protect the polarizing film from external mechanical damage, extend the service life of the first polarizing film 4 and the second polarizing film 5, reduce the impact of environmental pollutants on the polarizing film, keep the surface of the first polarizing film 4 and the second polarizing film 5 clean, maintain the good optical performance of the first polarizing film 4 and the second polarizing film 5, so that the sensor can still maintain high detection accuracy and stability during long-term use.

[0037] In some embodiments, the retroreflective photoelectric sensor 72 provided by this utility model includes a reflector 6 comprising multiple three-sided right-angled prisms. Each three-sided right-angled prism can retroreflect the incident light along its original path, ensuring retroreflection within a certain range regardless of the angle of the incident light, thus improving the sensor's angular tolerance. When the detection beam emitted by the transmitting end component 1 is converted into linearly polarized light after passing through the first polarizing film 4, it illuminates the three-sided right-angled prisms on the reflector 6. The light undergoes total internal reflection sequentially on the three reflecting surfaces, changing its polarization direction, and then retroreflects along its original path. The retroreflected light passes through the second polarizing film 5 and enters the receiving end component 2.

[0038] In some embodiments, multiple right-angled prisms are arranged in a matrix array, with the right-angle vertices of the prisms facing one side of the front cover 3. Corresponding right-angled edges of adjacent prisms are adjacent to each other, forming a continuous retroreflective surface within the reflector 6 area. Each right-angled prism consists of three mutually perpendicular reflective surfaces, forming a right-angled trihedron with its right-angled vertices facing one side of the front cover 3. The matrix arrangement of multiple right-angled prisms, with corresponding right-angled edges of adjacent prisms adjacent to each other, forms a continuous retroreflective surface, improving the efficiency of retroreflection. Simultaneously, the adjacent right-angled edges of adjacent prisms eliminate gaps between prisms, forming a continuous retroreflective surface and avoiding light loss at gaps. Furthermore, the right-angled vertices of the prisms facing the front cover 3 allow incident light to enter the prisms more directly, reducing the limitation of the incident angle, expanding the effective detection range, enhancing the sensor's anti-interference capability, and improving the sensor's ability to maintain high detection accuracy and stability in various complex environments.

[0039] In order to provide a detailed description of the electronic device 7 provided by this utility model, the above embodiments have provided a detailed description of a retroreflective photoelectric sensor 72. Based on the same utility model concept, this application also provides an electronic device 7.

[0040] Please see Figure 3 As shown, Figure 3 This is a schematic diagram of the structure of an electronic device 7 provided in an embodiment of the present invention. Embodiment two of the present invention provides an electronic device 7, which includes an execution body 71 and the aforementioned retroreflective photoelectric sensor 72. The retroreflective photoelectric sensor 72 is connected to the execution body 71 to control the corresponding function of the execution body 71. For example, the aforementioned electronic device 7 may include an automatic door control system, an object detection device on an industrial automated production line, a safety protection device, or other equipment requiring object detection. The execution body 71 may include a motor, relay, control circuit, or other actuator for performing specific control functions, such as starting or stopping equipment operation, opening or closing an automatic door, etc. After the retroreflective photoelectric sensor 72 is electrically connected to the execution body 71, it can transmit the detection signal to the execution body 71 via a signal line or wireless communication. When the retroreflective photoelectric sensor 72 detects that the detection beam is blocked or the received light intensity changes, it generates a corresponding electrical signal and transmits it to the execution body 71 to trigger the execution body 71 to perform the corresponding control action.

[0041] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although this utility model has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A retro-reflective photoelectric sensor, characterized by The retroreflection photoelectric sensor includes a transmitter assembly for emitting a probe beam, a receiver assembly for receiving the probe beam after retroreflection by a reflector, a front cover disposed between the transmitter assembly and the reflector for the light exit path and between the receiver assembly and the reflector for the light entrance path, and a first polarizing film and a second polarizing film respectively attached to the outer surface of the front cover. The first polarizing film covers the light exit port of the light exit path, and the second polarizing film covers the light entrance port of the light entrance path. The polarization directions of the first polarizing film and the second polarizing film are perpendicular to each other.

2. The retro-reflective photoelectric sensor according to claim 1, characterized in that The transmitter assembly includes a transmitter tube and a transmitter lens, and the front cover is located between the first polarizing film and the transmitter lens.

3. The retro-reflective photoelectric sensor according to claim 1, characterized in that The receiver assembly includes a receiver tube and a receiver lens, and the front cover is located between the second polarizing film and the receiver lens.

4. The retro-reflective photoelectric sensor according to claim 1, characterized in that, The front cover is made of injection-molded acrylic material.

5. The retro-reflective photosensor of claim 1, wherein, The perpendicularity error of the polarization axes of the first polarizing film and the second polarizing film does not exceed 0.1 degrees.

6. The retro-reflective photoelectric sensor according to claim 1, characterized in that The first polarizing film and the second polarizing film are respectively bonded to the outer surface of the front cover by an optically transparent adhesive.

7. The retro-reflective photosensor of claim 1, wherein, Both the first polarizing film and the second polarizing film have a scratch-resistant hard coating on the side opposite to the outer surface of the front cover.

8. The retro-reflective photoelectric sensor of claim 1, wherein, The reflector includes multiple three-sided right-angled prisms.

9. The retro-reflective photoelectric sensor according to claim 8, characterized in that Multiple right-angled prisms are arranged in a matrix array, with the right-angle vertices of the three-sided right-angled prisms facing one side of the front cover, and the corresponding right-angled edges of adjacent three-sided right-angled prisms are adjacent to each other, so as to continuously form a retroreflective surface in the reflector area.

10. An electronic device, comprising: The electronic device includes an execution body and a retroreflective photoelectric sensor as described in any one of claims 1 to 9, wherein the retroreflective photoelectric sensor is connected to the execution body to control the corresponding function of the execution body.

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