Photoelectric sensor and method for manufacturing the same

Abstract

Provided are a photoelectric sensor that can fully prevent dirt and can be firmly joined to a frame, and a method for manufacturing the same. A frame (12) in the photoelectric sensor (10) has an opening (121) through which at least one of light from a light projecting unit (14) and light toward a light receiving unit (16) passes, and is provided with a cover lens (50) that covers the opening (121) and transmits light. The cover lens (50) is joined to an edge (121a) of the frame (12) that defines the opening (121). An antifouling coating (61) is applied to an outer surface (51) of the cover lens (50), while an antifouling coating (61) is not applied to a joining portion (52a) of an inner surface (52) of the cover lens (50) that contacts the edge (121a).

Description

Technical Field

[0001] The invention relates to a photoelectric sensor and a method for manufacturing the same. Background Art

[0002] Photoelectric sensors are sometimes installed in, for example, production lines or equipment in factories to detect the presence or absence of workpieces.

[0003] The photoelectric sensor generally houses a light-emitting part for emitting light and a light-receiving part for receiving light inside a housing (hereinafter referred to as a frame). Moreover, inside the frame, in addition to housing a light-emitting element constituting the light-emitting part and a light-receiving element constituting the light-receiving part, a substrate is also housed, and the substrate is equipped with electronic components constituting a signal processing part, etc. The frame has an optical opening for allowing the detection light emitted from the light-emitting part and the return light received by the light-receiving part to pass through, and a cover or a cover-integrated lens as an optical component is sometimes provided at the opening. The cover lens functions as a light-emitting lens for the detection light to pass through and a light-receiving lens for the reflected light to pass through, or as a protection for these lenses. The following patent document 1 records an example of configuring such a cover lens on the front surface side of a light-emitting element or a light-receiving element.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2007-305673 Summary of the invention

[0007] Problems to be solved by the invention

[0008] When the photoelectric sensor is installed in a factory production line or equipment, the cover lens arranged on the front surface side of the light-projecting element or the light-receiving element may be contaminated by, for example, cleaning water, processing oil or dust. As a result, the amount of light transmitted through the cover lens may decrease, resulting in a decrease in the detection performance based on the photoelectric sensor.

[0009] The patent document 1 describes that a heat-crosslinkable or photo-crosslinkable resin composition is applied to the surface of the cover lens, but there is a problem that it does not have sufficient function as a countermeasure against dirt caused by the aforementioned cleaning water, processing oil or dust. In order to solve this problem, for example, there is an idea of ​​applying an antifouling coating to the cover lens. However, when a joining method is implemented in which the interface between the cover lens and the frame is melted and welded at a high temperature by laser welding, the antifouling coating material cannot be fully melted and is difficult to join with the frame because the melting point of the material constituting the antifouling coating is high. In addition, when a joining method is implemented in which an adhesive is used to join the interface between the cover lens and the frame, if the antifouling coating is exposed on the surface, the bonding is performed in a state where the antifouling coating is exposed on the surface, compared with the case of only the substrate, since the material constituting the antifouling coating material generally contains a fluorine-based compound, there is a problem that the bonding property of the adhesive to the cover lens and the frame is reduced. When using a photoelectric sensor in an environment where dirt is caused by processing oil or dust, it is ideal to prevent the cover lens from being dirty and to join the cover lens to the frame.

[0010] Therefore, an object of the present invention is to provide a photoelectric sensor including a cover lens that can sufficiently prevent contamination and can be firmly joined to a frame.

[0011] Technical means of solving problems

[0012] A photoelectric sensor according to an embodiment of the present invention accommodates at least one of a light-emitting portion that emits light and a light-receiving portion that receives light in a frame, wherein the frame has an opening for allowing at least one of light from the light-emitting portion and light toward the light-receiving portion to pass through, and the photoelectric sensor is provided with a cover lens that covers the opening and allows light to pass through, the cover lens being joined to an edge of the frame defining the opening, an anti-fouling coating being applied to an outer surface of the cover lens, and on the other hand, an anti-fouling coating is not applied to a portion of an inner surface of the cover lens that contacts the edge.

[0013] According to this embodiment, the outer surface of the cover lens is coated with an antifouling coating, so that even when the photoelectric sensor is used in an environment where it is contaminated by, for example, washing water, processing oil, or dust, it is possible to sufficiently prevent contamination. In addition, the portion of the inner surface of the cover lens that contacts the edge of the frame defining the opening is not coated with an antifouling coating, so that the portion and the edge of the frame can be firmly joined by, for example, laser welding. As a result, it is possible to provide a photoelectric sensor including a cover lens that can be sufficiently prevented from contamination and can be firmly joined to the frame.

[0014] In the above-mentioned embodiment, the material constituting the antifouling coating may also be formed into a layer structure in which the coating substrate and the coating agent are chemically cross-linked.

[0015] In the above embodiment, the portion of the inner surface of the cover lens that contacts the edge portion and the frame may be joined by laser welding. Also, the portion of the inner surface of the cover lens that contacts the edge portion and the frame may be joined by an adhesive.

[0016] According to the embodiment, the inner surface and the edge of the cover lens can be joined by laser welding or adhesive without using an antifouling coating. Since the material constituting the antifouling coating is generally a fluorine compound, it is possible to prevent the bonding strength from being weaker when bonding with an adhesive than when bonding to a substrate by mechanical means.

[0017] In the above embodiment, a mark indicating that the cover lens is disposed inside out in the frame may be printed on either the inner surface or the outer surface of the cover lens. Furthermore, when the cover lens is disposed inside out in the frame, the mark may be provided at a position in the cover lens that covers the light projection portion.

[0018] According to this embodiment, the mark printed on the inner surface of the cover lens is provided at a position in the cover lens that covers the light projection portion when the cover lens is disposed inside out in the frame, so that it can be easily determined that the cover lens is disposed inside out in the frame.

[0019] A photoelectric sensor according to an embodiment of the present invention accommodates at least one of a light-emitting portion that emits light and a light-receiving portion that receives light in a frame, wherein the frame has an opening for allowing at least one of light from the light-emitting portion and light toward the light-receiving portion to pass through, and the photoelectric sensor is provided with a cover lens, which covers the opening and allows light to pass through, and the cover lens is joined to an edge of the frame defining the opening, and a portion of the outer surface of the cover lens is applied with an anti-fouling coating, while another portion of the outer surface of the cover lens contacts the edge and is not applied with an anti-fouling coating.

[0020] A method for manufacturing a photoelectric sensor according to an embodiment of the present invention is provided with an opening in a frame body so as to allow at least one of light emitted from a light projecting portion contained in the frame body and light from the outside received by a light receiving portion to pass through, and the opening is covered with a cover lens, and the method for manufacturing the photoelectric sensor comprises the following steps: applying an antifouling coating to the outer surface and the inner surface of the cover lens; forming a region not applied with the antifouling coating in a part of the cover lens; providing the cover lens so as to cover the opening; and bonding the cover lens to the frame body in the region not applied with the antifouling coating.

[0021] Effects of the Invention

[0022] According to the present invention, it is possible to provide a photoelectric sensor including a cover lens that can be sufficiently prevented from being contaminated and can be firmly bonded to a frame body. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1This is a perspective view of the photoelectric sensor according to the embodiment as viewed from one direction.

[0024] Figure 2 Observed from the front Figure 1 Front view of the photoelectric sensor shown.

[0025] Figure 3A It is along Figure 2 Cross-sectional view of the VV line.

[0026] Figure 3B It is along Figure 2 Cross-sectional view along line VI-VI.

[0027] Figure 4 This is a diagram for explaining a state in which the cover lens is fitted into the opening with the inside and outside turned upside down.

[0028] Figure 5 This is a diagram showing an example of the spectral sensitivity characteristics of a light receiving element.

[0029] Figure 6 This is a diagram showing another example of the spectral sensitivity characteristics of the light receiving element.

[0030] Fig. 7A It is an explanatory diagram showing a coating structure of one layer.

[0031] Figure 7B It is an explanatory diagram showing a two-layer coating structure.

[0032] Figure 8 This is a cross-sectional view showing a modified example in which a cover lens is embedded from the inside.

[0033] [Explanation of Reference Numerals]

[0034] 10: Photoelectric sensor

[0035] 12: Frame

[0036] 14: Light projection department

[0037] 16: Light receiving part

[0038] 50: Cover lens

[0039] 61: Antifouling coating

[0040] 70: Mark

[0041] 121: Opening

[0042] 121a: Edge DETAILED DESCRIPTION

[0043] The embodiments of the present invention are described with reference to the accompanying drawings. Figure 1The illustrated case is a reference. In each figure, parts denoted by the same reference numerals have the same or similar structure.

[0044] like Figure 1 As shown, the photoelectric sensor 10 includes a frame 12. A light projecting unit 14 and a light receiving unit 16 are accommodated inside the frame 12. The frame 12 has an opening 121 for passing the detection light emitted from the light projecting unit 14 and the return light received by the light receiving unit 16, and a cover lens 50 is provided at the opening 121. In addition, on the outer surface of the frame 12, for example, a teach button 18 and an indicator 22 are provided. The following description is based on an example in which the light projecting unit 14 and the light receiving unit 16 are accommodated in the frame 12, but it is not limited to the example shown in the figure. In this embodiment, it is sufficient as long as at least one of the light projecting unit 14 and the light receiving unit 16 is accommodated in the frame 12. That is, the form in which the light projecting unit 14 and the light receiving unit 16 are accommodated in separate frames is also included in the sensor of this embodiment.

[0045] The light projecting unit 14 is a part that projects light to the object to be detected, and has a light emitting element and a light projecting lens. The light emitting element is, for example, a laser diode, and its optical axis X is parallel to the front-back direction. The light receiving unit 16 is a part that receives the reflected light of the light projected to the object to be detected, and has a light receiving element and a light receiving lens. The light receiving element is, for example, a photodiode or a position detecting element divided into two. As a detection principle for measuring the distance to the object to be detected, for example, the principle of time of flight (TOF) or triangulation distance measurement can be used. For example, when the triangulation distance measurement principle is used in the structure, the light emitted from the light emitting element is projected to the object to be detected through the light projecting lens, and the light reflected by the object to be detected is formed on the light receiving element through the light receiving lens. The light receiving element outputs two light receiving signals corresponding to the imaging position, and sends them to the control circuit via an amplifier. The amplifier and the control circuit are built into the photoelectric sensor 10, and in the control circuit, the position signal value calculated based on the two received light receiving signals is compared with the threshold value to find the distance to the object to be detected.

[0046] The teaching button 18 is a part that functions as a setting part for changing the setting of the sensor body, and has a function of receiving an input operation from the outside to set a threshold. Here, the so-called threshold refers to a reference value used to judge the detection of the object to be detected or the distance to the object to be detected in the photoelectric sensor 10, and is one of the sensitivity parameters used to adjust the sensitivity. As sensitivity parameters, in addition to the threshold, the power of the light emitted from the light-emitting part 14, that is, the light intensity, or the amplification factor of the amount of light received by the light-receiving part 16, that is, the gain, etc. can also be listed. For example, in the case of a transparent object to be detected with low reflectivity, a high light intensity is set. When the user presses the teaching button 18, a teaching process is performed to set the sensitivity parameter including at least the threshold, and the sensitivity parameter including at least the threshold is automatically set to a certain value. As teaching processes, for example, there are one-point teaching processes and two-point teaching processes, and the content thereof has been described in detail in the previous patent documents of the present applicant (for example, Japanese Patent Laid-Open No. 2008-298614), etc., so the description is omitted here.

[0047] The indicator 22 lights up according to the power supply status or detection status of the photoelectric sensor 10. For example, the indicator 22 has a power light that lights up when the power is turned on and an operation display light that lights up when the object to be detected is detected. The power light and the operation display light each include, for example, a light emitting diode (LED), and light up in different display colors.

[0048] The frame 12 is formed of, for example, resin or metal, and has a substantially rectangular parallelepiped shape. The frame 12 has a front surface 31, a back surface 32, a top surface 33, a bottom surface 34, a side surface 35, and a side surface 36 with respect to the six faces constituting the rectangular parallelepiped. The front surface 31 and the back surface 32 face each other with the inside of the frame 12 sandwiched therebetween. Similarly, the top surface 33 and the bottom surface 34 face each other with the inside of the frame 12 sandwiched therebetween, and the side surface 35 and the side surface 36 face each other with the inside of the frame 12 sandwiched therebetween. The up-down direction of the front surface 31 and the back surface 32 is formed to be longer than the left-right direction. Similarly, the front-back direction of the top surface 33 and the bottom surface 34 is formed to be longer than the left-right direction, and the up-down direction of the side surface 35 and the side surface 36 is formed to be longer than the front-back direction. The top surface 33 is adjacent to the front surface 31 and extends in a direction orthogonal to the front surface 31 and the back surface 32. On the top surface 33, the indicator 22 and the teaching button 18 are provided in order from the front surface 31 side.

[0049] A cable 40 is connected to the bottom surface 34 of the housing 12. The cable 40 is used, for example, to transmit a detection signal indicating a detection result obtained by the photoelectric sensor 10 to the outside of the photoelectric sensor 10.

[0050] In addition, the frame 12 contains a structure generally provided as a photoelectric sensor (e.g., a light projecting element, a light receiving element, a substrate equipped with a light projecting circuit (not shown) for driving the light projecting element, and a light receiving circuit (not shown) for electrically processing the light receiving signal of the light receiving element. The aforementioned cable 40 has a cable core wire (not shown) inside, and the cable core wire passes through the inside of the frame 12 and is connected to the substrate disposed in the frame 12. In addition, the "substantially rectangular parallelepiped shape" related to the frame 12 does not mean a rectangular parallelepiped with all internal angles of 90 degrees, but includes a case where at least one corner of such a rectangular parallelepiped is chamfered.

[0051] In frame 12, as Figure 1 As shown in FIG. 1 , a cover lens 50 (transparent acrylic cover lens) as an optical component is provided in a manner to close the opening 121 for projecting and receiving light. In other words, the photoelectric sensor 10 is provided with a window in which the cover lens 50 is embedded on the front surface of the frame 12. The cover lens 50 has the function of covering the opening 121 and transmitting light. The cover lens 50 is bonded to the edge 121a of the frame 12 defining the opening 121 (see FIG. 1 ). Figure 2 ).

[0052] The structure of the cover lens 50 will be further described. Figure 2 Observed from the front Figure 1 A front view of the photosensor 10 is shown. Figure 3A It is along Figure 2 Cross-sectional view of the VV line. Figure 3B It is along Figure 2 Cross-sectional view along line VI-VI.

[0053] In this embodiment, an antifouling coating 61 is applied to the outer surface 51 (the surface on the front side) of the cover lens 50. The antifouling coating 61 uses, for example, a material containing a fluorine compound. The material used for the antifouling coating 61 is not limited to this example, and for example, a material containing at least one of a silicon compound, a silicon dioxide compound, or a titanium oxide compound can be used. Moreover, these antifouling coating materials are chemically cross-linked with the substrate to form a one-layer structure (a one-layer coating structure). The one-layer coating structure and the two-layer coating structure are described below.

[0054] Fig. 7A This is an example of a coating structure in which the coating agent formed on the surface of the cover lens 50 is set as a single layer. Figure 7B This is an example of a coating structure in which the coating agent formed on the surface of the cover lens 50 is a two-layer coating agent.

[0055] In the case where the cover lens 50 is formed with a coating agent, a conventional coating agent such as Figure 7BAs shown, a two-layer coating structure (coating agent 610 and coating substrate 620) is formed, but there is the following problem at this time, that is, interference phenomenon will occur, resulting in instability of characteristics and production deviation. Figure 5 as well as Figure 6 While explaining.

[0056] Figure 5 The graph G1 shows the spectral sensitivity characteristics when a single-layer coated optical thin film layer exists in the light receiving path from the cover lens 50 to the light receiving element. Figure 6 The diagram G2 shows the spectral sensitivity characteristics of the light receiving portion 16 (light receiving element) of the photoelectric sensor 10 when the path from the cover lens 50 to the light receiving element is set as a two-layer coating (a coating structure of two adjacent layers of a 1945nm thick SiO2 coating (refractive index 1.46) and an 800nm ​​thick Si3N4 coating (refractive index 2.05)). Figure 5 as well as Figure 6 The horizontal axis represents the wavelength of light, and the vertical axis represents the spectral sensitivity. Figure 5 As shown in FIG. 1 , it can be seen that the visible light region is transmitted, while the ultraviolet light and infrared light regions are roughly blocked. Figure 6 As shown in the spectral sensitivity characteristics of the double-layer coating structure, it can be seen that the spectral sensitivity characteristics fluctuate due to the interference caused by the two-layer coating, and a large increase or decrease in light sensitivity occurs for a small wavelength change. In photoelectric sensors, single-wavelength red (about 660nm) or infrared (about 950nm) LEDs or laser diodes (LD) are often used as light sources. Figure 6 Such fluctuating spectral sensitivity characteristics have the problem of large sensitivity fluctuations due to manufacturing variations or temperature changes between individual photoelectric sensors. When the antifouling coating is set as a two-layer coating structure, the same interference phenomenon occurs, resulting in characteristic instability and production variations.

[0057] In order to solve the above problem, in this embodiment, two layers of coating agent ( Figure 7B The coating substrate 620 shown is chemically cross-linked with the coating agent 610, thereby forming a layer of coating agent 61 ( Fig. 7A ) constitutes an antifouling coating. By forming an antifouling coating with a layer of coating agent 61, as shown in FIG. Figure 5 as well as Figure 6 As described above, the spectral sensitivity characteristics of the cover lens 50 have less deviation when the wavelength changes, and the slope of the change is more stable than that of the two-layer coating agent. As a result, even when the temperature characteristics of the light source or the coating agent change, stable optical characteristics can be provided.

[0058] However, if the antifouling coating 61 is applied to the entire inner surface 52 of the cover lens 50, it is difficult to join the cover lens 50 to the frame 12 by laser welding because the material constituting the antifouling coating 61 has a high melting point. Furthermore, if the antifouling coating 61 is exposed on the frame joining surface during joining, the bonding property of the cover lens 50 and the frame 12 by the adhesive is deteriorated compared to the case of only the base material (the case without the antifouling coating).

[0059] Therefore, in this embodiment, the antifouling coating 61 is not applied to the joint portion (hereinafter, also referred to as the back peripheral edge portion 52a of the cover lens 50) of the inner surface 52 (the surface on the rear side) of the cover lens 50 that contacts at least the edge portion 121a of the frame body 12 defining the opening 121. Thus, when the cover lens 50 is joined to the frame body 12, the back peripheral edge portion 52a of the cover lens 50 and the edge portion 121a of the frame body 12 can be joined by laser welding or adhesive.

[0060] In addition, in the present embodiment, as long as the antifouling coating 61 is not applied to at least the back peripheral edge portion 52a, the antifouling coating 61 may be applied to or may not be applied to the portion of the inner surface 52 of the cover lens 50 other than the back peripheral edge portion 52a. In other words, when the cover lens 50 is bonded to the frame 12, the antifouling coating 61 may be applied to or may not be applied to the portion of the cover lens 50 other than the portion in contact with the frame 12.

[0061] The material of the cover lens substrate (cover lens body) is not particularly limited, and for example, a material including at least one of acrylic resin, polycarbonate resin, polyarylate resin, or glass is used.

[0062] The cover lens 50 is manufactured by the following steps. According to the above steps, the antifouling coating can be efficiently manufactured on one side of the substrate.

[0063] (1) A coating agent is applied to the surface of a substrate by a method such as curtain coating.

[0064] (2) The coating agent is cured by drying and ultraviolet (UV) irradiation. At this time, the fluorine layer is precipitated on the surface of the coating agent by UV irradiation, and the antifouling coating layer 61 is formed.

[0065] (3) Print the mark 70 on the back surface by screen printing or other methods.

[0066] (4) Each cover lens 50 is cut out by milling or the like.

[0067] Next, the frame body 12 and the cover lens 50 are assembled through the following steps to manufacture the photosensor 10 .

[0068] (1) The manufactured cover lens 50 is disposed at a position covering the opening 121 of the frame body 12. At this time, the rear peripheral edge portion 52a of the cover lens 50 is in contact with the edge portion 121a of the frame body 12.

[0069] (2) The cover lens 50 is bonded to the frame body 12 by laser welding the back peripheral edge portion 52 a of the cover lens 50 and the edge portion 121 a of the frame body 12 , or by applying an adhesive and curing the adhesive.

[0070] The inner surface 52 of the cover lens 50 is printed with a mark 70. The mark 70 is provided when the cover lens 50 is embedded in the frame 12 with the inside and outside reversed. Figure 4 As shown, the position of the cover lens 50 covering the projection unit 14. By printing the mark 70 on the cover lens 50 in this way, when the cover lens 50 is inserted into the opening 121 of the frame 12 (that is, when the edge of the inner surface 52 of the cover lens 50 is joined to the peripheral edge of the opening 121 in the frame 12), it can be determined whether the cover lens 50 is inside out, thereby preventing the cover lens 50 from being mistakenly arranged inside out in the frame 12.

[0071] In addition, it is desirable that the mark 70 printed on the inner surface 52 of the mask lens 50 is provided so as not to cross, for example, Figure 4 The position of the central axis AX (the axis passing through the center of the cover lens 50 in the left-right direction and extending in the up-down direction) of the cover lens 50 shown in the figure. However, it is not limited to such a position. As mentioned above, as long as the position of the mark 70 covers the position of the projection unit 14 when the cover lens 50 is embedded in the frame 12 with the inside out, it can also be set at a position crossing the aforementioned central axis AX, and this position is not particularly limited. Moreover, as long as the mark 70 in this embodiment has the function of distinguishing that the cover lens 50 is embedded in the frame 12 with the inside out, it is not limited to being printed on the inner surface 52, and various embodiments can be adopted.

[0072] (Variation of the embodiment)

[0073] In the above-described embodiment, the cover lens 50 is embedded from the outside of the frame 12 toward the inside, but it may also be as follows. Figure 8 As shown, the cover lens 50 is inserted from the inside to the outside of the frame 12. At this time, the outer surface 51 of the cover lens 12 only needs to form a region 51a where the antifouling coating 61 is not applied, and the cover lens 50 and the frame 12 are bonded in the region 51a by laser welding or adhesive.

[0074] The area 51b coated with the antifouling coating 61 is formed to be the same size as or slightly larger than the opening 121. Since the cover lens 50 is formed to be larger than the opening 121 of the frame 12, the area 51a not coated with the antifouling coating 61 is formed to surround the area 51b coated with the antifouling coating 61. The area 51a is another example of a joining portion that contacts the edge 121a of the frame 12, similar to the aforementioned back peripheral edge 52a.

[0075] The embodiments described above are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The various elements and their configurations, materials, conditions, shapes, and sizes included in the embodiments are not limited to the examples and can be appropriately changed. Moreover, the structures shown in different embodiments can be partially replaced or combined with each other.

[0076] (Note)

[0077] 1. A photoelectric sensor 10, wherein at least one of a light projecting unit 14 for emitting light and a light receiving unit 16 for receiving light is accommodated in a frame 12, wherein

[0078] The housing 12 has an opening 121 through which at least one of the light from the light projecting unit 14 and the light toward the light receiving unit 16 passes.

[0079] A cover lens 50 is provided, which covers the opening 121 and transmits light.

[0080] The cover lens 50 is bonded to the edge 121a of the frame body 12 defining the opening 121.

[0081] The antifouling coating 61 is applied to the outer surface 51 of the cover lens 50 , whereas the antifouling coating 61 is not applied to the portion of the inner surface 52 of the cover lens 50 that contacts the edge portion 121 a .

Claims

1. A photoelectric sensor, wherein at least one of a light projecting unit for emitting light and a light receiving unit for receiving light is housed in a frame, wherein the photoelectric sensor is characterized in that: The frame has an opening through which at least one of the light from the light projecting unit and the light toward the light receiving unit passes. The photoelectric sensor is provided with a cover lens that covers the opening and transmits the light. The cover lens is bonded to an edge of the frame defining the opening. The outer surface of the cover lens is coated with an antifouling coating, while the inner surface of the cover lens in contact with the edge portion is not coated with the antifouling coating. The material constituting the antifouling coating layer is formed into a layer structure in which the coating substrate and the antifouling coating material are chemically cross-linked.

2. The photoelectric sensor according to claim 1, characterized in that: A portion of the inner surface of the cover lens that contacts the edge portion is joined to the frame body by laser welding.

3. The photoelectric sensor according to claim 1, characterized in that: A portion of the inner surface of the cover lens that contacts the edge portion is bonded to the frame body by an adhesive.

4. The photoelectric sensor according to claim 1, characterized in that: A mark indicating that the cover lens is disposed inside out in the frame is printed on either the inner surface or the outer surface of the cover lens.

5. The photoelectric sensor according to claim 4, characterized in that: When the cover lens is disposed on the frame body with the inside and outside turned upside down, the mark is provided at a position of the cover lens that covers the light projecting portion.

6. The photoelectric sensor according to claim 1, characterized in that: The material constituting the antifouling coating layer is one or more compounds selected from the group consisting of fluorine compounds, silicon compounds, silicon dioxide compounds, and titanium oxide compounds.

7. A photoelectric sensor, wherein at least one of a light projecting unit for emitting light and a light receiving unit for receiving light is housed in a frame, wherein the photoelectric sensor is characterized in that: The frame has an opening through which at least one of the light from the light projecting unit and the light toward the light receiving unit passes. The photoelectric sensor is provided with a cover lens that covers the opening and transmits the light. The cover lens is bonded to an edge of the frame defining the opening. A portion of the outer surface of the cover lens is coated with an antifouling coating, while another portion of the outer surface of the cover lens contacts the edge and is not coated with the antifouling coating. The material constituting the antifouling coating layer is formed into a layer structure in which the coating substrate and the antifouling coating material are chemically cross-linked.

8. A method for manufacturing a photoelectric sensor, characterized in that: The photoelectric sensor is provided with an opening in a frame body in a manner that at least one of light emitted from a light projecting portion contained in the frame body and light from the outside received by a light receiving portion passes through, and the opening is covered with a cover lens. The manufacturing method of the photoelectric sensor includes the following steps: Applying an antifouling coating to the outer surface and the inner surface of the cover lens, wherein the material constituting the antifouling coating is formed into a layer structure in which a coating substrate and an antifouling coating material are chemically cross-linked; creating an area on a portion of the mask lens to which the anti-fouling coating is not applied; disposing the cover lens in a manner to cover the opening; as well as The cover lens and the frame are bonded to the region of the cover lens where the antifouling coating is not applied.

Images