Photoelectric sensor

Abstract

To suppress incidence of stray light on a light-receiving element.SOLUTION: A photoelectric sensor 1 comprises: an optical block 40 that has a floodlighting element 62 emitting detection light L1 toward an object, a hood 52 with a restriction hole 52c through which reflection light L2 from the object passes, and a light-receiving element 66 receiving the reflection light L2 which has passed through the restriction hole 52c; a case 10 storing the optical block 40 that has an open hole 12c through which the detection light L1 and the reflection light L2 pass; and a front face cover 20 that is attached to the case 10 so as to block the open hole 12c and through which the detection light L1 and the reflection light L2 are transmitted. The front face cover 20 has a protruded part 21 heading for the open hole 12c that projects from a cover inner surface 20b toward the hood 52. In the protruded part 21, a protrusion top face 21a heading for the hood 52 comes into contact with a hood front face 52a on a front face cover 20 side of the hood 52 and covers the restriction hole 52c.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a photoelectric sensor.

Background Art

[0002] Conventionally, a photoelectric sensor including a light emitting element and a light receiving element has been known. As an example of a photoelectric sensor, there is a displacement sensor described in Patent Document 1, for example. This displacement sensor irradiates an object with light from a light emitting unit, receives the reflected light from the object by a light receiving unit such as an image sensor, and measures the displacement, surface shape, etc. of the object based on the received light signal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a photoelectric sensor, the light emitted from the light emitting unit may become stray light and enter the light receiving unit, which may affect measurements and the like. For this reason, it is required to suppress the incidence of stray light on the light receiving unit.

[0005] An object of the present disclosure is to provide a photoelectric sensor capable of suppressing the incidence of stray light from the light emitting element to the light receiving element.

Means for Solving the Problems

[0006] The photoelectric sensor of the present disclosure includes an optical block having a light projecting element that emits detection light toward an object, a hood having a limiting hole through which the reflected light from the object passes, and a light receiving element that receives the reflected light that has passed through the limiting hole, a case that houses the optical block and has an opening through which the detection light and the reflected light pass, and a front cover that is attached to the case so as to close the opening and through which the detection light and the reflected light are transmitted. The front cover has a convex portion that protrudes from the inner surface of the cover facing the opening toward the hood. The top surface of the convex portion facing the hood is in contact with the front surface of the hood on the side of the front cover of the hood and covers the limiting hole.

Advantages of the Invention

[0007] According to the photoelectric sensor of the present disclosure, the incidence of stray light on the light receiving element can be suppressed.

Brief Description of the Drawings

[0008]

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DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the photoelectric sensor will be described with reference to the accompanying drawings. The following embodiments illustrate configurations and methods for embodying the technical idea, and do not limit the materials, shapes, structures, arrangements, dimensions, etc. of each component to those described below. Note that the accompanying drawings may show the components enlarged for easy understanding. The dimensional ratios of the components may be different from the actual ones or those in other drawings. Also, in the cross-sectional views, hatching of some components may be omitted for easy understanding. In this specification, "parallel" and "orthogonal" include not only the cases of strict parallelism and orthogonality, but also the cases that are generally parallel and orthogonal within the scope where the effects of this embodiment are achieved. Note that the present invention is not limited to these examples, and is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0010] (Overall Configuration of Photoelectric Sensor) FIGS. 1 to 7 show the photoelectric sensor 1 of this embodiment. The photoelectric sensor 1 of this embodiment is a reflection type photoelectric sensor that emits detection light and receives the reflected light reflected by the detection target by the detection light to detect the detection target. Here, the direction in which the detection light is emitted is defined as "front", and the side opposite to the front is defined as "rear". Also, the photoelectric sensor 1 of this embodiment has a cable 2. The side where the cable 2 is provided is defined as "downward", and the side opposite to the downward is defined as "upward". In the figure, the front is illustrated by an arrow X, and the upward is illustrated by an arrow Z. Also, the right direction when viewed from the rear to the front is illustrated by an arrow Y. Note that when arranging the photoelectric sensor 1, the "downward" in the photoelectric sensor 1 does not necessarily have to be vertically downward. The photoelectric sensor 1 can be arranged with the "front", "rear", "downward", and "upward" in the photoelectric sensor 1 facing in any direction.

[0011] As shown in FIGS. 1 and 2, the photoelectric sensor 1 of this embodiment has a rectangular parallelepiped shape that is long in the vertical direction. The photoelectric sensor 1 has a front surface 1a, a rear surface 1b, side surfaces 1c, 1d, an upper surface 1e, a lower surface 1f, and an inclined surface 1g. The front surface 1a and the rear surface 1b face opposite sides in the front-rear direction (X direction) of the photoelectric sensor 1. The side surfaces 1c, 1d face opposite sides in the left-right direction (Y direction) of the photoelectric sensor 1. The upper surface 1e and the lower surface 1f face opposite sides in the vertical direction (Z direction) of the photoelectric sensor 1. The inclined surface 1g is inclined with respect to the lower surface 1f and the rear surface 1b. The photoelectric sensor 1 has a cable 2 led out from the inclined surface 1g.

[0012] As shown in FIG. 1, a front cover 20 is provided on the front surface 1a. The front cover 20 constitutes a part of the front surface 1a of the photoelectric sensor 1. The detection light and the reflected light pass through the front cover 20.

[0013] As shown in FIG. 2, a display unit 31 and an operation unit 32 are provided on the rear surface 1b. The display unit 31 displays the setting information and the like of the photoelectric sensor 1. The operation unit 32 is operated for setting, changing, etc. of the setting information.

[0014] (Case) As shown in FIGS. 1 to 4, the photoelectric sensor 1 has a case 10. The case 10 is in the shape of a rectangular box that is long in the Z direction. The case 10 includes a case body 11 and a cover plate 18. FIG. 4 shows the optical block 40 housed in the case 10 with the cover plate 18 and the like omitted.

[0015] The case body 11 has a front plate 12, side plates 13, a rear plate 14, an upper plate 15, a lower plate 16, and an inclined plate 17. The front plate 12 and the rear plate 14 are arranged in the X direction. The upper plate 15 and the lower plate 16 are arranged in the Z direction. The side plates 13 and the cover plate 18 are arranged in the Y direction. The front plate 12, the rear plate 14, the upper plate 15, the lower plate 16, and the inclined plate 17 are provided perpendicular to the side plates 13. The front plate 12, the upper plate 15, the rear plate 14, the inclined plate 17, and the lower plate 16 are connected to each other in this order. Thereby, the case body 11 has a side opening 11a on one side. The cover plate 18 is attached to the case body 11 so as to close the side opening 11a of the case body 11. The cover plate 18 constitutes a part of the side surface 1d of the photoelectric sensor 1.

[0016] The side opening 11a is formed by the front plate 12, the rear plate 14, the upper plate 15, the lower plate 16, and the inclined plate 17 of the case 10. As shown in FIGS. 2, 4, and 5, the cable 2 is inserted through a through hole that penetrates the inclined plate 17. The cable 2 is fixed to the inclined plate 17 by a fixing member 93.

[0017] As shown in FIG. 3, a front cover 20 is attached to the front plate 12. The front plate 12 has a cover housing portion 12a where the front cover 20 is disposed. The cover housing portion 12a is formed to be recessed from the front surface 1a toward the inside of the case 10 and has a bottom portion 12b. Further, the front plate 12 has an opening hole 12c through which the detection light and the reflected light pass. The opening hole 12c penetrates the bottom portion 12b of the cover housing portion 12a. Therefore, the front cover 20 is attached to the case 10 so as to close the opening hole 12c.

[0018] As shown in FIGS. 5 and 6, a groove portion 12d is formed along the periphery of the cover accommodating portion 12a at the bottom 12b of the cover accommodating portion 12a. An adhesive is applied to the groove portion 12d. The adhesive fixes the front cover 20 to the front plate 12 of the case body 11. That is, the front cover 20 is attached to the case 10 by the adhesive.

[0019] (Optical block) As shown in FIGS. 4 to 7, an optical block 40 is accommodated in the case 10. The optical block 40 is disposed in the case body 11 through a side opening 11a formed in the case body 11 of the case 10. The side opening 11a is closed by a cover plate 18 attached to the case body 11. Thereby, the optical block 40 is accommodated in the case 10.

[0020] The optical block 40 has a holder 50, a light transmitting and receiving block 60, and a circuit board 70. The holder 50 has a base plate 51, a hood 52, a board support portion 53, and a board fixing portion 54. The base plate 51 is formed in a plate shape.

[0021] As shown in FIGS. 4 and 5, the base plate 51 is positioned in the case body 11 and fixed to the side plate 13 of the case body 11 by screws 91a. Specifically, the upper end 51b of the base plate 51 abuts against the inner surface 15a of the upper plate 15 of the case body 11. Also, the front end 51a of the base plate 51 abuts against the inner surface 12e of the front plate 12 of the case body 11. In this way, the base plate 51 is positioned by the upper plate 15 and the front plate 12 of the case body 11.

[0022] As shown in FIG. 7, the hood 52, the board support portion 53, and the board fixing portion 54 are erected on the base plate 51. The hood 52 is formed in a substantially rectangular parallelepiped shape. As shown in FIGS. 4 and 5, the hood 52 has a hood front surface 52a facing the side (front) of the front cover 20 and a hood rear surface 52b facing the side opposite to the hood front surface 52a (rear). In the present embodiment, the hood front surface 52a is flush with the front end 51a of the base plate 51. That is, the hood 52 does not protrude forward of the front end 51a of the base plate 51. Further, the hood 52 has a restriction hole 52c penetrating the hood 52 from the hood front surface 52a to the hood rear surface 52b.

[0023] The substrate support portion 53 supports the circuit board 70. The substrate fixing portion 54 is formed in a quadrangular prism shape. The substrate fixing portion 54 is formed with a fixing hole 54a penetrating the substrate fixing portion 54 in the X direction. The circuit board 70 is fixed by a fixing screw (see FIG. 5) 91b screwed into the fixing hole 54a of the substrate fixing portion 54.

[0024] The light projecting and receiving block 60 includes a light projecting block 61 and a light receiving block 64. The light projecting block 61 and the light receiving block 64 are arranged in the Z direction. The light projecting block 61 is arranged above the light receiving block 64. In the light projecting and receiving block 60 of the present embodiment, the light projecting block 61 and the light receiving block 64 are integrally formed.

[0025] A light projecting element 62 and a light projecting lens 63 are arranged in the light projecting block 61. The light projecting element 62 is constituted by, for example, a laser diode. The light projecting element 62 and the light projecting lens 63 are arranged so as to emit detection light toward the front of the photoelectric sensor 1.

[0026] A light receiving lens 65 and a light receiving element 66 are arranged in the light receiving block 64. The light receiving element 66 is constituted by, for example, a photodiode. The light receiving lens 65 and the light receiving element 66 are arranged so that the reflected light incident on the photoelectric sensor 1 from the front of the photoelectric sensor 1 is received by the light receiving element 66.

[0027] As shown in FIG. 5, in the light transmitting and receiving block 60 of the present embodiment, the front end 64a of the light receiving block 64 is configured to be located on the side of the front cover 20 with respect to the front end 61a of the light transmitting block 61.

[0028] The light transmitting and receiving block 60 has a plurality of connection pins 67. The plurality of connection pins 67 penetrate the circuit board 70. The plurality of connection pins 67 are connected to the wiring (land) of the circuit board 70 by solder. That is, the light emitting element 62 and the light receiving element 66 are electrically connected to the circuit board 70. The light transmitting and receiving block 60 is mounted on the circuit board 70. A connector 71 is mounted on the circuit board 70. The light transmitting and receiving block 60 is connected to the connector 71 by the wiring of the circuit board 70. This connector 71 is connected to the main circuit board 72 shown in FIG. 6 by a cable (not shown). The circuit board 70 is fixed to the board fixing portion 54 of the holder 50. Therefore, the light transmitting and receiving block 60 is fixed to the holder 50 via the circuit board 70. Then, as shown in FIGS. 5 and 6, the light receiving block 64 of the light transmitting and receiving block 60 is positioned so as to receive the light that has passed through the restriction hole 52c of the hood 52 with respect to the hood 52 of the holder 50.

[0029] (Front Cover) As shown in FIG. 5, the front cover 20 has light transmissibility that allows the detection light L1 emitted from the light transmitting block 61 of the light transmitting and receiving block 60 to pass through. Also, for the reflected light L2 by the object, the front cover 20 allows it to pass through. This reflected light L2 passes through the restriction hole 52c of the hood 52 and enters the light receiving block 64 of the light transmitting and receiving block 60. The detection light L1 and the reflected light L2 pass through the opening hole 12c of the case 10 (case body 11).

[0030] As shown in FIGS. 5 and 6, the front cover 20 has a cover inner surface 20b facing the opening hole 12c of the case 10. Also, the front cover 20 has a cover outer surface 20a facing the side opposite to the cover inner surface 20b.

[0031] The front cover 20 has a convex portion 21 that protrudes from the inner surface 20b of the cover toward the hood 52 of the optical block 40. The convex portion 21 is disposed within the opening hole 12c of the case 10 (case body 11). The convex portion 21 has a convex top surface 21a that faces the same direction as the inner surface 20b of the cover.

[0032] The convex portion 21 is formed such that the convex top surface 21a contacts the hood front surface 52a of the hood 52. For example, the convex portion 21 is formed such that the convex top surface 21a is flush with the inner surface 12e of the front plate 12 of the case body 11.

[0033] Further, the convex portion 21 has convex side surfaces 21b, 21c, 21d, 21e between the convex top surface 21a and the inner surface 20b of the cover. As shown in FIG. 5, the convex side surfaces 21b, 21c are arranged so as to sandwich the convex top surface 21a in the Z direction. The convex side surfaces 21b, 21c are inclined such that the distance therebetween decreases from the inner surface 20b of the cover toward the convex top surface 21a. As shown in FIG. 6, the convex side surfaces 21d, 21e are arranged so as to sandwich the convex top surface 21a in the Y direction. The convex side surfaces 21d, 21e are inclined such that the distance therebetween decreases from the inner surface 20b of the cover toward the convex top surface 21a.

[0034] As shown in FIGS. 5 and 6, the front cover 20 has a recess 22. The recess 22 is formed to be recessed from the cover outer surface 20a toward the restriction hole 52c of the hood 52. The recess 22 is composed of a recess bottom surface 22a facing the same direction (front) as the cover outer surface 20a, and recess side surfaces 22b, 22c, 22d, 22e between the cover outer surface 20a and the recess bottom surface 22a. As shown in FIG. 5, the recess side surfaces 22b, 22c are arranged so as to sandwich the recess bottom surface 22a in the Z direction. The recess side surfaces 22b, 22c are inclined such that the interval between them becomes larger from the recess bottom surface 22a toward the cover outer surface 20a. As shown in FIG. 6, the recess side surfaces 22d, 22e are arranged so as to sandwich the recess bottom surface 22a in the Y direction. The recess side surfaces 22d, 22e are inclined such that the interval between them becomes larger from the recess bottom surface 22a toward the cover outer surface 20a. As shown in FIGS. 5 and 6, when viewed from the X direction of the front cover 20, the recess bottom surface 22a is formed to be larger than the opening diameter of the restriction hole 52c.

[0035] The front cover 20 is formed such that the thickness T2 of the front cover 20 between the convex top surface 21a and the recess bottom surface 22a is the same as the thickness T1 of the front cover 20 between the cover inner surface 20b and the cover outer surface 20a. The fact that the thicknesses are "the same" is intended to mean the same in terms of specifications, and is the same even in the case of variations due to manufacturing errors.

[0036] Also, in the front cover 20, the thickness between the inclined surfaces inclined with respect to the cover outer surface 20a and the cover inner surface 20b is the same as the above thicknesses T1, T2. Specifically, the thicknesses between the recess side surface 22b and the convex side surface 21b, and between the recess side surface 22c and the convex side surface 21c shown in FIG. 5 are the same as the above thicknesses T1, T2. Also, the thicknesses between the recess side surface 22d and the convex side surface 21d, and between the recess side surface 22e and the convex side surface 21e shown in FIG. 6 are the same as the above thicknesses T1, T2.

[0037] As shown in Fig. 3, the bottom surface 22a of the concave portion is rectangular in the upper part and is formed in an arc shape that protrudes downward in the lower part. The side surface 22b of the concave portion above the bottom surface 22a is formed in a substantially rectangular shape when viewed from the thickness direction (X direction) of the front cover 20. As shown in Fig. 5, the convex side surface 21b that partially overlaps the concave side surface 22b in the X direction is formed in a substantially rectangular shape when viewed from the X direction, similar to the concave side surface 22b.

[0038] The concave side surface 22c located below the bottom surface 22a of the concave portion is formed in an arc shape that protrudes downward. As shown in Fig. 5, the convex side surface 21c that partially overlaps the concave side surface 22c in the X direction is formed in an arc shape that protrudes downward, similar to the concave side surface 22c.

[0039] As shown in Fig. 5, the detection light L1 and the reflected light L2 pass through the front cover 20. Therefore, the front cover 20 has a detection light transmission region 23 through which the detection light L1 passes and a reflected light transmission region 24 through which the reflected light L2 passes. The convex portion 21 and the concave portion 22 of the front cover 20 include the detection light transmission region 23 and the reflected light transmission region 24.

[0040] The detection light L1 enters the front cover 20 at the convex side surface 21b and exits the front cover 20 at the concave side surface 22b. Therefore, the convex side surface 21b can be said to be a detection light incident surface 21b where the detection light L1 enters the front cover 20. Also, the concave side surface 22b can be said to be a light projection surface 22b that projects the detection light L1 exiting the front cover 20 toward the object. The detection light incident surface 21b is inclined with respect to the optical axis of the detection light L1. In the light projection and reception block 60, the light projection block 61 is arranged above the light reception block 64. Therefore, the light projection element 62 is arranged above the light reception element 66. And the detection light incident surface 21b is inclined so as to face the opposite side to the light reception element 66 arranged in the light reception block 64. And the light projection surface 22b is inclined so as to be parallel to the detection light incident surface 21b.

[0041] The reflected light L2 enters the front cover 20 at the bottom surface 22a of the concave portion and exits from the front cover 20 at the top surface 21a of the convex portion. Therefore, the bottom surface 22a of the concave portion can be said to be a light-receiving surface 22a that receives the reflected light L2 from the object. Further, the top surface 21a of the convex portion can be said to be a reflected-light emitting surface 21a from which the reflected light L2 exits the front cover 20.

[0042] The light-projecting surface 22b (side surface 22b of the concave portion) is formed between the light-receiving surface 22a (bottom surface 22a of the concave portion) and the outer surface 20a of the cover. Therefore, it can be said that the light-projecting surface 22b and the light-receiving surface 22a are formed continuously. Further, the detection-light incident surface 21b (side surface 21b of the convex portion) is formed between the reflected-light emitting surface 21a (top surface 21a of the convex portion) and the inner surface 20b of the cover. Therefore, it can be said that the detection-light incident surface 21b and the reflected-light emitting surface 21a are formed continuously.

[0043] The main circuit board 72 shown in FIG. 6 is connected to the display unit 31 and the operation unit 32 by a connector (not shown) and the like. For example, a plurality of circuit elements constituting a control circuit are mounted on the main circuit board 72 and the circuit board 70.

[0044] The control circuit performs operations such as emitting the detection light L1 by the light-projecting element 62, detecting the object by the reflected light L2 at the light-receiving element 66, and outputting a detection signal according to the detection result. The control circuit is configured to detect an object by, for example, the TOF (Time Of Flight) method. Further, the control circuit performs operations such as displaying the detection result and settings on the display unit 31 and changing the settings by operating the operation unit 32.

[0045] (Operation) Next, the operation of the above-described photoelectric sensor 1 will be described. First, a comparative example of the photoelectric sensor 1 of the above embodiment will be described. In the description of the comparative example, the same members as those of the photoelectric sensor 1 of the above embodiment are denoted by the same reference numerals.

[0046] FIG. 8 shows the photoelectric sensor 110 of the first comparative example. This photoelectric sensor 110 includes a front cover 111 having a cover inner surface 111b and a cover outer surface 111a that are entirely flat with respect to the front cover 20 of the above-described embodiment. That is, the front cover 111 is separated from the hood 52, and a gap 112 is formed. In this photoelectric sensor 110, the detection light L1 reflected by the cover inner surface 111b of the front cover 111 enters the restriction hole 52c from the gap 112 and is received by the light receiving element 66. The detection light L1 (stray light) that enters in this way affects the detection of the object. As described above, in the TOF type photoelectric sensor 110, the object is detected based on the time from the emission of the detection light L1 to the incidence of the reflected light L2 by the object. Therefore, the detection light L1 (stray light) that enters from the gap 112 becomes a factor of false detection in the photoelectric sensor 110.

[0047] FIG. 9 shows the photoelectric sensor 120 of the second comparative example. This photoelectric sensor 120 has a front cover 121 that is entirely flat, similar to the photoelectric sensor 110 of the first comparative example described above. The front cover 121 has a cover outer surface 121a and a cover inner surface 121b. In the photoelectric sensor 120 of the second comparative example, the front end 124a of the hood 124 of the holder 123 that constitutes the optical block 122 protrudes into the opening hole 12c of the case 10 and is in contact with the cover inner surface 121b of the front cover 121. In this photoelectric sensor 120 of the second comparative example, it is possible to prevent the detection light L1 reflected by the cover inner surface 121b of the front cover 121 from entering the light receiving element 66 from the restriction hole 52c. However, since the operator must arrange the holder 123 in the case 10 so that the front end 124a of the hood 124 is disposed in the opening hole 12c of the case 10, it affects the workability of assembly. Further, when arranging the holder 123 in the case 10, care must be taken so that the hood 124 protruding from the base plate 125 of the holder 123 does not interfere with the case 10, which affects the workability of assembly.

[0048] In contrast, the photoelectric sensor 1 of the present embodiment has a convex portion 21 on the front cover 20. When viewed from the Z direction, the convex portion 21 is larger than the restriction hole 52c of the hood 52. The top surface 21a of the convex portion 21 is in contact with the front surface 52a of the hood 52. Therefore, there is no gap between the front cover 20 and the hood 52 in the photoelectric sensor 1 of the present embodiment. Therefore, the photoelectric sensor 1 of the present embodiment can suppress the incidence of stray light on the light receiving element 66.

[0049] In the present embodiment, the front surface 52a of the hood is flush with the front end 51a of the base plate 51. That is, the hood 52 does not protrude forward from the front end 51a of the base plate 51. Therefore, the holder 50 can be housed in the case body 11 such that the front end 51a of the base plate 51 is along the front plate 12 of the case body 11. And since the front surface 52a of the hood does not protrude forward from the front end 51a of the base plate 51, there is no need to pay attention to prevent the hood 52 from interfering with the case body 11, and the workability can be improved. Also, like the photoelectric sensor 120 of the second comparative example described above, since there is no need to move the housed holder 50 forward toward the case body 11, the workability can be improved.

[0050] The front cover 20 has a concave portion 22 that is recessed from the cover outer surface 20a facing the side opposite to the cover inner surface 20b toward the restriction hole 52c. The concave portion 22 is composed of a concave bottom surface 22a facing the same direction as the cover outer surface 20a and concave side surfaces 22b to 22e between the cover outer surface 20a and the concave bottom surface 22a. Therefore, the convex portion 21 and the concave portion 22 can suppress the front cover 20 from becoming too thick in part.

[0051] The thickness T2 of the front cover 20 between the top surface 21a of the convex portion and the bottom surface 22a of the concave portion is the same as the thickness T1 of the front cover 20 between the outer cover surface 20a and the inner cover surface 20b. The thicknesses between the side surface 22b of the concave portion and the side surface 21b of the convex portion, and between the side surface 22c of the concave portion and the side surface 21c of the convex portion are the same as the above thicknesses T1 and T2. Also, the thicknesses between the side surface 22d of the concave portion and the side surface 21d of the convex portion, and between the side surface 22e of the concave portion and the side surface 21e of the convex portion shown in FIG. 6 are the same as the above thicknesses T1 and T2. Therefore, the thickness (wall thickness) of the front cover 20 can be made uniform.

[0052] The side surfaces 22b to 22e of the concave portion are inclined such that the distance between the side surfaces 22b to 22e of the concave portion in the direction parallel to the outer cover surface 20a increases from the bottom surface 22a of the concave portion toward the outer cover surface 20a. Therefore, compared with a case where the bottom surface 22a of the concave portion and the side surfaces 22b to 22e form a right angle, dust and the like adhering to the concave portion 22 can be easily wiped off.

[0053] Viewed from the X direction, the bottom surface 22a of the concave portion 22 is formed larger than the opening diameter of the restriction hole 52c. If the bottom surface 22a of the concave portion is smaller than the restriction hole 52c, the reflected light L2 incident on the restriction hole 52c may be blocked by the bottom surface 22a of the concave portion. Therefore, it is possible to suppress the bottom surface 22a of the concave portion from blocking the reflected light L2 incident on the restriction hole 52c of the hood 52.

[0054] The front cover 20 has a detection light transmission region 23 through which the detection light L1 passes. In the detection light transmission region 23, the detection light incident surface 21b where the detection light L1 enters the front cover 20 is inclined with respect to the optical axis of the detection light L1. By the detection light incident surface 21b inclined in this way, it is possible to suppress the detection light L1 from being reflected toward the light projecting element 62.

[0055] The detection light incident surface 21b is inclined so as to face the side opposite to the light receiving element 66. Therefore, as shown by the dashed two-dot line in FIG. 5, the detection light L1 is reflected to the side opposite to the light receiving element 66. For this reason, it is possible to further suppress the detection light L1 from entering the light receiving element 66.

[0056] The detection light incident surface 21b is formed so as to connect the convex portion top surface 21a and the cover inner surface 20b. Further, the light projection surface 22b is formed so as to connect the concave portion bottom surface 22a and the cover outer surface 20a.

[0057] Among the concave portion side surfaces 22b to 22e, the concave portion side surface 22c on the side opposite to the light projection surface 22b is formed in an arc shape that protrudes downward when viewed from the side of the cover outer surface 20a of the front cover 20. Therefore, dust or the like adhering to the concave portion 22 can be easily wiped off.

[0058] The case 10 has a front plate 12 to which the front cover 20 is attached and an upper plate 15 that constitutes the upper surface 1e of the case 10. The holder 50 of the optical block 40 is housed in the case 10 so as to be in contact with the front plate 12 and the upper plate 15. Therefore, the holder 50 can be easily positioned. And the optical block 40 attached to the holder 50 can be easily positioned.

[0059] (Effect) As described above, according to the present embodiment, the following effects are obtained. (1) The photoelectric sensor 1 includes an optical block 40 having a light projection element 62 that emits detection light L1 toward an object, a hood 52 having a restriction hole 52c through which the reflected light L2 by the object passes, and a light receiving element 66 that receives the reflected light L2 that has passed through the restriction hole 52c, a case 10 that houses the optical block 40 and has an opening hole 12c through which the detection light L1 and the reflected light L2 pass, and a front cover 20 that is attached to the case 10 so as to close the opening hole 12c and through which the detection light L1 and the reflected light L2 transmit. The front cover 20 has a convex portion 21 that protrudes from the cover inner surface 20b toward the hood 52 toward the opening hole 12c. The convex portion top surface 21a of the convex portion 21 that faces the hood 52 is in contact with the hood front surface 52a on the front cover 20 side of the hood 52 and covers the restriction hole 52c.

[0060] According to this configuration, when viewed from the Z direction, the convex portion 21 is larger than the restriction hole 52c of the hood 52. The top surface 21a of the convex portion 21 is in contact with the front surface 52a of the hood 52. Therefore, in the photoelectric sensor 1 of the present embodiment, no gap is generated between the front cover 20 and the hood 52. Therefore, the photoelectric sensor 1 of the present embodiment can suppress the incidence of stray light to the light receiving element 66.

[0061] (2) The front surface 52a of the hood is flush with the front end 51a of the base plate 51. That is, the hood 52 does not protrude forward from the front end 51a of the base plate 51. Therefore, the holder 50 can be housed in the case body 11 such that the front end 51a of the base plate 51 is along the front plate 12 of the case body 11. And since the front surface 52a of the hood does not protrude forward from the front end 51a of the base plate 51, there is no need to pay attention to the hood 52 not interfering with the case body 11, and the workability can be improved. Also, like the photoelectric sensor 120 of the second comparative example above, since there is no need to move the housed holder 50 forward toward the case body 11, the workability can be improved.

[0062] (3) The front cover 20 has a concave portion 22 that is recessed from the cover outer surface 20a facing the side opposite to the cover inner surface 20b toward the restriction hole 52c. The concave portion 22 is composed of a concave bottom surface 22a facing the same direction as the cover outer surface 20a and concave side surfaces 22b to 22e between the cover outer surface 20a and the concave bottom surface 22a. Therefore, the convex portion 21 and the concave portion 22 can suppress the front cover 20 from becoming too thick in part.

[0063] (4) The thickness T2 of the front cover 20 between the top surface 21a of the convex portion and the bottom surface 22a of the concave portion is the same as the thickness T1 of the front cover 20 between the outer cover surface 20a and the inner cover surface 20b. The thicknesses between the side surface 22b of the concave portion and the side surface 21b of the convex portion, and between the side surface 22c of the concave portion and the side surface 21c of the convex portion are the same as the above thicknesses T1 and T2. Also, the thicknesses between the side surface 22d of the concave portion and the side surface 21d of the convex portion, and between the side surface 22e of the concave portion and the side surface 21e of the convex portion shown in FIG. 6 are the same as the above thicknesses T1 and T2. Therefore, the thickness (wall thickness) of the front cover 20 can be made uniform. Thereby, the front cover 20 can be easily formed.

[0064] (5) The side surfaces 22b to 22e of the concave portion are inclined such that the intervals between the side surfaces 22b to 22e of the concave portion in the direction parallel to the outer cover surface 20a increase from the bottom surface 22a of the concave portion toward the outer cover surface 20a. Therefore, compared with the case where the bottom surface 22a of the concave portion and the side surfaces 22b to 22e are formed to be at right angles, dust and the like attached to the concave portion 22 can be easily wiped off.

[0065] (6) When viewed from the X direction, the bottom surface 22a of the concave portion is formed to be larger than the opening diameter of the restriction hole 52c. If the bottom surface 22a of the concave portion is smaller than the restriction hole 52c, the reflected light L2 incident on the restriction hole 52c may be blocked by the bottom surface 22a of the concave portion. Therefore, it is possible to suppress the bottom surface 22a of the concave portion from blocking the reflected light L2 incident on the restriction hole 52c of the hood 52.

[0066] (7) The front cover 20 has a detection light transmission region 23 through which the detection light L1 passes. In the detection light transmission region 23, the detection light incident surface 21b on which the detection light L1 is incident on the front cover 20 is inclined with respect to the optical axis of the detection light L1. Due to the detection light incident surface 21b inclined in this way, it is possible to suppress the detection light L1 from being reflected toward the light projecting element 62.

[0067] (8) The detection light incident surface 21b is inclined so as to face the side opposite to the light receiving element 66. Therefore, it is possible to further suppress the detection light L1 from being incident on the light receiving element 66. (9) The detection light incident surface 21b is formed so as to connect the convex portion top surface 21a and the cover inner surface 20b. Further, the light projection surface 22b is formed so as to connect the concave portion bottom surface 22a and the cover outer surface 20a.

[0068] (10) Among the concave portion side surfaces 22b to 22e, the concave portion side surface 22c on the side opposite to the light projection surface 22b is formed in an arc shape that protrudes downward when viewed from the side of the cover outer surface 20a of the front cover 20. Therefore, dust or the like attached to the concave portion 22 can be easily wiped off.

[0069] (11) The case 10 has a front plate 12 to which the front cover 20 is attached and an upper plate 15 that constitutes the upper surface 1e of the case 10. The holder 50 of the optical block 40 is housed in the case 10 so as to be in contact with the front plate 12 and the upper plate 15. Therefore, the holder 50 can be easily positioned. And the optical block 40 attached to the holder 50 can be easily positioned.

[0070] (Modification example) The description of the above embodiment is an exemplification of the forms that the photoelectric sensor related to the present disclosure can take, and is not intended to limit that form. The present disclosure can take forms other than the embodiment, for example, modification examples of the embodiments shown below, and forms in which at least two modification examples that do not conflict with each other are combined.

[0071] · With respect to the above embodiment, the shape of the front cover 20 can be appropriately changed. The front cover 201 of the photoelectric sensor 200 shown in FIG. 10 has a convex portion 202 and does not have the concave portion 22 of the above embodiment. That is, the entire cover outer surface 201a of the front cover 201 is flat. Further, the convex portion 202 is formed only at the portion in contact with the hood 52. Furthermore, the convex portion 202 is formed such that the convex portion side surface 202a forms a right angle with respect to the cover inner surface 201b. Also with the front cover 201 configured in this way, it is possible to suppress the detection light emitted from the light projection element 62 and reflected by the front cover 201 from entering the light receiving element 66.

[0072] The front cover 211 of the photoelectric sensor 210 shown in FIG. 11 has a convex portion 212 and a concave portion 213. The convex portion 212 is formed such that the convex side surface 212a forms a right angle with respect to the cover inner surface 211b. The concave portion 213 is formed such that the concave side surface 213a forms a right angle with respect to the cover outer surface 211a. Even with the front cover 211 configured in this way, the thickness (wall thickness) can be made substantially uniform.

[0073] The front cover 221 of the photoelectric sensor 220 shown in FIG. 12 has a cover outer surface 221a and a cover inner surface 221b. And the front cover 221 has a convex portion 222 and a concave portion 223. The convex portion 222 is formed such that the convex side surface 222a forms a right angle with respect to the cover inner surface 221b. The concave portion 223 is formed such that the concave side surface 223a is a slope. In the front cover 221 configured in this way, dust or the like adhering to the concave portion 223 can be easily wiped off.

[0074] The front cover 231 of the photoelectric sensor 230 shown in FIG. 13 has a cover outer surface 231a and a cover inner surface 231b. And the front cover 231 has a convex portion 232 and a concave portion 233. In the concave portion 233, the concave side surface 233b above the concave bottom surface 233a is configured such that the detection light L1 passes through. Further, the concave side surface 233b is inclined with respect to the optical axis of the detection light L1. Also, the concave side surface 233b above the convex top surface 232a is configured such that the detection light L1 passes through. Further, the convex side surface 232b is inclined with respect to the optical axis of the detection light L1. The inclined convex side surface 232b can suppress the reflected detection light L1 from going toward the light projecting element 62.

[0075] The front cover 241 of the photoelectric sensor 240 shown in FIG. 14 has a cover outer surface 241a and a cover inner surface 241b. And the front cover 241 has a convex portion 242 and a concave portion 243. In the concave portion 243, the concave side surface 243b above the concave bottom surface 243a is configured such that the detection light L1 passes through. The convex top surface 242a of the convex portion 242 extends upward, and the detection light L1 is incident on the convex top surface 242a.

[0076] The front cover 251 of the photoelectric sensor 250 shown in FIG. 15 has a cover outer surface 251a and a cover inner surface 251b. And the front cover 251 has a convex portion 252 and a concave portion 253. The convex portion 252 has a convex top surface 252a that extends upward. The concave portion 253 has a concave bottom surface 253a that extends upward. In this front cover 251, the detection light L1 passes through the convex top surface 252a and the concave bottom surface 253a.

[0077] The front cover 261 of the photoelectric sensor 260 shown in FIG. 16 has a cover outer surface 261a and a cover inner surface 261b. And the front cover 261 has a convex portion 262 and a concave portion 263. The concave portion 263 has a concave bottom surface 263a that extends upward, and the detection light L1 passes through. The convex portion 262 has an intermediate surface 262c that is located between the convex top surface 262a and the cover inner surface 261b in the X direction. The intermediate surface 262c is, for example, parallel to the convex top surface 262a. The detection light L1 is incident on this intermediate surface 262c. The intermediate surface 262c may be inclined with respect to the optical axis of the detection light L1.

[0078] ·In the above embodiment, the light projecting and receiving block 60 in which the light projecting block 61 and the light receiving block 64 are integrated is used. In contrast, a configuration in which the light projecting block 61 and the light receiving block 64 are divided may be used.

[0079] The above description is merely illustrative. Those skilled in the art can recognize that there are many more possible combinations and substitutions other than the components and methods (manufacturing processes) enumerated for the purpose of explaining the technology of the present disclosure. The present disclosure is intended to encompass all alternatives, modifications, and variations that are included within the scope of the present disclosure, including the claims. [Appendix 1] An optical block including a light projecting element that emits detection light toward an object, a hood having a limiting hole through which reflected light from the object passes, and a light receiving element that receives the reflected light that has passed through the limiting hole; A case that houses the optical block and has an opening hole through which the detection light and the reflected light pass; A front cover that is attached to the case so as to close the opening hole and through which the detection light and the reflected light transmit; Comprising; The front cover has a convex portion that protrudes from the inner surface of the cover facing the opening hole toward the hood; The convex portion is such that the top surface of the convex portion facing the hood contacts the front surface of the hood on the side of the front cover of the hood and covers the limiting hole; Photoelectric sensor. [Appendix 2] The front cover has a concave portion that recesses from the outer surface of the cover facing the opposite side toward the limiting hole; The concave portion is composed of a bottom surface of the concave portion facing the same direction as the outer surface of the cover and a side surface of the concave portion between the outer surface of the cover and the bottom surface of the concave portion; The photoelectric sensor according to Appendix 1. [Appendix 3] The thickness of the front cover between the top surface of the convex portion and the bottom surface of the concave portion is equal to the thickness of the front cover between the outer surface of the cover and the inner surface of the cover; The photoelectric sensor according to Appendix 2. [Appendix 4] The side surface of the concave portion is inclined such that the distance between the side surfaces of the concave portion in a direction parallel to the outer surface of the cover increases from the bottom surface of the concave portion toward the outer surface of the cover; The photoelectric sensor according to Appendix 2 or Appendix 3. [Appendix 5] Viewed from the thickness direction of the front cover, the concave portion is formed such that the bottom surface of the concave portion is larger than the opening diameter of the limiting hole. The photoelectric sensor according to any one of Appendices 2 to 4. [Appendix 6] The front cover has a detection light transmission region through which the detection light transmits; In the detection light transmission region, the detection light incident surface where the detection light enters the front cover is inclined with respect to the optical axis of the detection light; The photoelectric sensor according to any one of Appendices 2 to 5. [Appendix 7] The detection light incident surface is inclined so as to face the side opposite to the light receiving element. The photoelectric sensor according to Appendix 6. [Appendix 8] The detection light incident surface is formed so as to connect the top surface of the convex portion and the inner surface of the cover. The photoelectric sensor according to Appendix 6 or Appendix 7. [Appendix 9] A part of the side surface of the concave portion is a light projecting surface from which the detection light exits the front cover in the detection light transmission region and is parallel to the detection light incident surface. The optoelectronic sensor according to any one of Appendices 6 to 8. [Appendix 10] The light projecting surface is formed so as to connect the bottom surface of the concave portion and the outer surface of the cover. The optoelectronic sensor according to Appendix 9. [Appendix 11] Of the side surfaces of the concave portion, the side surface opposite to the light projecting surface is formed in an arc shape that protrudes downward when viewed from the side of the outer surface of the front cover. The optoelectronic sensor according to Appendix 9 or Appendix 10. [Appendix 12] The optical block includes a base plate provided with the hood and a light projecting and receiving block on which the light projecting element and the light receiving element are arranged. The optoelectronic sensor according to any one of Appendices 1 to 11. [Appendix 13] The optical block includes a circuit board on which the light projecting and receiving block is mounted and is electrically connected to the light projecting element and the light receiving element. The base plate has a substrate support portion and a substrate fixing portion for fixing the circuit board. The optoelectronic sensor according to Appendix 12. [Appendix 14] The case has a front plate to which the front cover is attached and an upper plate that constitutes the upper surface of the case. The optical block is housed in the case so as to be in contact with the front plate and the upper plate. The optoelectronic sensor according to any one of Appendices 1 to 13.

Explanation of Symbols

[0080] 1 Photoelectric sensor 1a Front surface 1b Rear surface 1c Side surface 1d Side surface 1e Upper surface 1f Lower surface 1g Inclined surface 2 Cable 10 Case 11 Case body 11a Lateral opening 12 Front plate 12a Cover housing portion 12b Bottom 12c Opening hole 12d Groove portion 12e Inner surface 13 Side plate 14 Rear plate 15 Upper plate 15a Inner surface 16 Lower plate 17 Inclined plate 18 Cover plate 20 Front cover 20a Cover outer surface 20b Cover inner surface 21 Protrusion 21a Protrusion top surface (reflected light emission surface) 21b Protrusion side surface (detection light incident surface) Side of the convex part from 21c to 21e 22 Concave part 22a Bottom surface of the concave part (light-receiving surface) 22b Side surface of the concave part (light-projecting surface) 22c - 22e Side surfaces of the concave part 23 Detection light transmission area 24 Reflected light transmission area 31 Display part 32 Operation part 40 Optical block 50 Holder 51 Base plate 51a Front end 51b Upper end 52 Hood 52a Front surface of the hood 52b Rear surface of the hood 52c Limiting hole 53 Substrate support part 54 Substrate fixing part 54a Fixing hole 60 Light transmitting and receiving block 61 Light projecting block 61a Front end 62 Light projecting element 63 Light projecting lens 64 Light receiving block 64a Front end 65 Light receiving lens 66 Light receiving element 67 Connection pin 70 Circuit board 71 Connector 72 Main circuit board 91a Screw 91b Fixing screw 93 Fixing member 110 Photoelectric sensor 111 Front cover 111a Outer surface of the cover 111b Inner surface of the cover 112 Gap 120 Photoelectric sensor 121 Front cover 121b Inner surface of the cover 122 Optical block 123 Holder 124 Hood 124a Front end 125 Base plate 200 Photoelectric sensor 201 Front cover 201b Inner surface of the cover 202 Protrusion 202a Side surface of the protrusion 210 Photoelectric sensor 211 Front cover 211a Outer surface of the cover 211b Inner surface of the cover 212 Protrusion 212a Side surface of the protrusion 213 Recess 213a Side surface of the recess 220 Photoelectric sensor 221 Front cover 222 Protrusion 222a Side surface of the protrusion 223 Recess 223a Side surface of the recess 230 Photoelectric sensor 231 Front cover 232 Protrusion 232a Top surface of the protrusion 232b Side surface of the protrusion 233 Recess 233a Bottom surface of the recess 233b Side surface of the recess 240 Photoelectric sensor 241 Front cover 242 Protrusion 242a Top surface of the protrusion 243 Recess 250 Photoelectric sensor 251 Front cover 252 Protrusion 252a Top surface of the protrusion 253 Recess 253a Bottom surface of the recess 260 Photoelectric sensor 261 Front cover 261b Inner surface of the cover 262 Protrusion 262a Top surface of the protrusion 262c Intermediate surface 263 Concave part L1 Detection light L2 Reflected light T1 Thickness T2 Thickness X, Y, Z directions

Claims

1. An optical block including a light projecting element that emits detection light toward an object, a hood having a limiting hole through which reflected light from the object passes, and a light receiving element that receives the reflected light that has passed through the limiting hole; a case that houses the optical block and has an opening through which the detection light and the reflected light pass; a front cover attached to the case so as to close the opening and through which the detection light and the reflected light are transmitted; characterized by comprising: the front cover has a convex portion that protrudes from an inner surface of the cover facing the opening toward the hood; the convex portion is such that a top surface of the convex portion facing the hood contacts a front surface of the hood on the side of the front cover of the hood and covers the limiting hole; a photoelectric sensor.

2. the front cover has a concave portion that is recessed from an outer surface of the cover facing the opposite side toward the limiting hole; the concave portion is composed of a bottom surface of the concave portion facing the same direction as the outer surface of the cover and a side surface of the concave portion between the outer surface of the cover and the bottom surface of the concave portion; the photoelectric sensor according to claim 1.

3. a thickness of the front cover between the top surface of the convex portion and the bottom surface of the concave portion is equal to a thickness of the front cover between the outer surface of the cover and the inner surface of the cover; the photoelectric sensor according to claim 2.

4. the side surface of the concave portion is inclined such that a distance between side surfaces of the concave portion in a direction parallel to the outer surface of the cover increases from the bottom surface of the concave portion toward the outer surface of the cover; the photoelectric sensor according to claim 2.

5. when viewed from a thickness direction of the front cover, the concave portion is formed such that the bottom surface of the concave portion is larger than an opening diameter of the limiting hole; the photoelectric sensor according to claim 2.

6. the front cover has a detection light transmission region through which the detection light is transmitted; in the detection light transmission region, a detection light incident surface on which the detection light is incident on the front cover is inclined with respect to an optical axis of the detection light; the photoelectric sensor according to claim 2.

7. the detection light incident surface is inclined so as to face the side opposite to the light receiving element; the photoelectric sensor according to claim 6.

8. the detection light incident surface is formed so as to connect the top surface of the convex portion and the inner surface of the cover; the photoelectric sensor according to claim 6.

9. a part of the side surface of the concave portion is a light projecting surface on which the detection light is emitted from the front cover in the detection light transmission region and is parallel to the detection light incident surface; the photoelectric sensor according to claim 6.

10. The photoelectric sensor according to claim 9, wherein the light projection surface is formed so as to connect the bottom surface of the recess and the outer surface of the cover.

11. The photoelectric sensor according to claim 9, wherein among the side surfaces of the recess, the side surface of the recess opposite to the light projection surface is formed in an arc shape that protrudes downward when viewed from the side of the outer surface of the front cover.

12. The photoelectric sensor according to any one of claims 1 to 11, wherein the optical block includes a base plate provided with the hood and a light projection / reception block on which the light projection element and the light reception element are arranged.

13. The optical block includes a circuit board on which the light projection / reception block is mounted and which is electrically connected to the light projection element and the light reception element. The base plate has a substrate support portion and a substrate fixing portion for fixing the circuit board. The photoelectric sensor according to claim 12.

14. The case has a front plate to which the front cover is attached and an upper plate that constitutes the upper surface of the case. The optical block is housed in the case so as to be in contact with the front plate and the upper plate. The photoelectric sensor according to any one of claims 1 to 11.

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