Lens and optical sensor system

Abstract

The purpose of the present disclosure is to improve convergence accuracy for incident light in a distance range in which the distance to a lens is wider. The lens (1) comprises: a lens surface region (2) having a lens surface (20) that converges incident light; a non-lens surface region (3) in which no lens surface (20) is present. The lens surface (20) includes: a first lens surface (21) which is a convex lens surface and is configured as a convex curved surface (CV1) having an apex (P1); and a second lens surface (22) which is aspheric and has a curvature different from that of the first lens surface (21). The principal ray axis (222) of the second lens surface (22) is non-coaxial with the principal ray axis (211) of the first lens surface (21).

Description

Technical Field

[0001] The present disclosure relates generally to lenses and optical sensor systems. More particularly, the present disclosure relates to lenses having a lens surface that concentrates incident light, and also to optical sensor systems including such lenses. Background Art

[0002] Patent document 1 discloses a laser radar device. The laser radar device includes a laser radar unit and a controller for the laser radar unit. The laser radar unit includes an optical block. The optical block includes: a light-emitting element, which serves as a light source of a laser beam; a projecting lens, which defines the projection axis of the laser beam; a light-receiving lens, which is used to converge a reflected light beam, which is a laser beam reflected from an object; and a photosensitive element, which is used to receive the reflected light beam converged by the light-receiving lens. The light-receiving lens is provided with a long-range lens portion, which is aspherical and can guide a reflected light beam parallel to the light-receiving axis to the photosensitive element. In addition, the light-receiving lens is also provided with a short-range lens portion, which is cylindrical, the center of which is defined by a central axis perpendicular to the light-receiving axis, and can guide a portion of the reflected light beam parallel to the light-receiving axis and a portion of the reflected light beam not parallel to the light-receiving axis to the photosensitive element. This laser radar device achieves the advantage of broadening the detection range of objects.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-47141 Summary of the Invention

[0006] According to Patent Document 1, a distance equal to or shorter than 1.5m is defined as a "short distance," and a distance longer than 1.5m is defined as a "long distance." That is, according to Patent Document 1, the short-distance lens portion and the long-distance lens portion are set with a distance of 1.5m as their boundary. However, the light-receiving lens (lens) disclosed in Patent Document 1 may not ensure a sufficient amount of received light for a light beam from a light source at an extremely short distance of 50mm, a distance of up to 5m (in other words, a distance much shorter than 1.5m), or a distance greater than 1.5m.

[0007] In view of the foregoing background, an object of the present disclosure is therefore to provide a lens and also to provide an optical sensor system that helps to more accurately focus incident light even if the incident light has traveled a distance falling within a wider range before entering the lens.

[0008] A lens according to one aspect of the present disclosure includes: a lens surface region having a lens surface that converges incident light; and a non-lens surface region in which no lens surface is present. The lens surface includes: a first lens surface that is a convex lens surface and is configured as a convexly curved surface having a vertex; and a second lens surface that is an aspherical surface and has a different curvature than the first lens surface. The axis of a principal ray defined with respect to the second lens surface is not coaxial with the axis of the principal ray defined with respect to the first lens surface.

[0009] According to another aspect of the present disclosure, an optical sensor system includes a light projector, the lens described above, and a photosensitive element. The light projector projects a laser beam toward an object to be measured. The lens focuses reflected light from the object to be measured. The photosensitive element receives the light focused by the lens and converts it into an electrical signal. The photosensitive element is configured to align its light receiving axis with the optical axis passing through the vertex. The light projector and light receiving axis are parallel to each other relative to the optical axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] [ Figure 1 ] Figure 1 is a perspective view illustrating the appearance of a lens according to an exemplary embodiment when viewed from the front of the lens;

[0011] [ Figure 2 ] Figure 2 is a schematic front view of the lens;

[0012] [ Figure 3 ] Figure 3 is a lens sag graph showing a lens sag depth of the lens relative to the vertex of the first lens surface;

[0013] [ Figure 4 ] Figure 4 A is a conceptual diagram illustrating a case where an optical sensor system including a lens is used in a “long-range” application; Figure 4 B is a conceptual diagram illustrating a case where an optical sensor system is used in an “ultra-close range” application;

[0014] [ Figure 5 ] Figure 5 shows a block diagram of the structure used in the optical sensor system;

[0015] [ Figure 6 ] Figure 6 A is a perspective view illustrating the appearance of a plano-convex lens for explaining the first lens surface of the lens; Figure 6 B is a perspective view illustrating the appearance of a cylindrical lens for explaining the second lens surface of the lens;

[0016] [ Figure 7 ] Figure 7 is a graph showing distance measurement characteristics of a lens;

[0017] [ Figure 8 ] Figure 8 A is a conceptual diagram illustrating application example 1 of the optical sensor system; Figure 8 B is a conceptual diagram illustrating application example 2 of the optical sensor system;

[0018] [ Figure 9 ] Figure 9 A is a schematic front view illustrating a variation 1-1 of the lens; Figure 9 B is a schematic front view illustrating another example of variation 1-1 of the lens;

[0019] [ Figure 10 ] Figure 10 A is a schematic front view illustrating variation 1-2 of the lens; Figure 10 B is a schematic front view illustrating another example of Variation 1-2 of the lens;

[0020] [ Figure 11 ] Figure 11 is a schematic front view illustrating a variation 2 of the lens;

[0021] [ Figure 12 ] Figure 12 A is a schematic front view illustrating variation 3 of the lens; Figure 12 B is a schematic front view illustrating another example of Variation 3 of the lens;

[0022] [ Figure 13 ] Figure 13 A is a schematic front view illustrating a variation 4 of the lens; Figure 13 B is along Figure 13 A cross-sectional view taken along plane II shown in FIG.

[0023] [ Figure 14 ] Figure 14 A is a schematic front view illustrating yet another example of variation 4 of the lens; Figure 14 B is along Figure 14 A cross-sectional view taken along the plane II-II shown in FIG.

[0024] [ Figure 15 ] Figure 15 A is a schematic front view illustrating a variation 5 of the lens; Figure 15 B is a perspective view illustrating the appearance of the annular lens for explaining the second lens surface according to Modification 5; Figure 15 C is a perspective view illustrating the appearance of a cylindrical lens;

[0025] [ Figure 16 ] Figure 16is a conceptual diagram illustrating cross-sectional shapes of a plurality of light projection spots for explaining a modification (Modification 6) of a light projection section included in the optical sensor system;

[0026] [ Figure 17 ] Figure 17 is a graph showing distance measurement characteristics of a plurality of lenses corresponding to a plurality of projection spots, covering a detection distance of 100 mm to 400 mm;

[0027] [ Figure 18 ] Figure 18 A is a schematic front view illustrating a variation 7 of the lens; Figure 18 B is along Figure 18 A cross-sectional view taken along plane III-III shown in FIG.

[0028] [ Figure 19 ] Figure 19 is a perspective view illustrating the appearance of a variation 8 of the lens when viewed from the front of the lens;

[0029] [ Figure 20 ] Figure 20 A is shown Figure 1 Characteristic diagram of light intensity distribution of the lens shown; Figure 20 B is a characteristic diagram showing light intensity distribution according to modification 8 of the lens;

[0030] [ Figure 21 ] Figure 21 is a graph showing distance measurement characteristics of Variation 8 of the lens; and

[0031] [ Figure 22 ] Figure 22 is a perspective view illustrating the appearance of a cylindrical lens for explaining a second lens surface according to Modification 8 of the lens. DETAILED DESCRIPTION

[0032] (summary)

[0033] A lens and optical sensor system according to exemplary embodiments and their variations will now be described with reference to the accompanying drawings. Note that the embodiments and their variations described below are merely exemplary embodiments and their variations of the various embodiments of the present disclosure and should not be construed as limiting. Rather, the exemplary embodiments and their variations can be readily modified in various ways based on design choices or any other factors without departing from the scope of the present disclosure. Note that the variations described below can be employed in appropriate combinations.

[0034] The drawings referred to in the following description of the embodiment and its modifications are all schematic representations. Therefore, the ratios of the sizes (including thicknesses) of the various components illustrated in the drawings do not always reflect their actual size ratios.

[0035] For example, the lens 1 according to one aspect (refer to Figure 1 ) is assumed to be applied to the optical sensor system 100 (reference Figure 5 ). In particular, as an example, it is assumed that the optical sensor system 100 is a so-called "time of flight (TOF)" sensor (system) 200 for measuring the distance to the measurement object Ob1 based on the flight time of light. The lens 1 is assumed to be applied as the light receiving lens 7 of the TOF sensor 200 (see Figure 5 However, lens 1 is not necessarily used as the light-receiving lens 7 of TOF sensor 200. Alternatively, lens 1 can also be used as a light-receiving lens of a photosensor used to detect, for example, the presence or absence of an object (such as glass, metal, non-metal, or liquid) or any changes in the surface condition of the object. Alternatively, lens 1 can also be used as a lens for a system used to analyze the properties of a material based on, for example, reflected light from a laser beam irradiating the material.

[0036] like Figure 1 As shown, the lens 1 includes: a lens surface area 2, which has a function of converging incident light (such as reflected light Op2; reference Figure 4 A and Figure 4 B) lens surface 20; non-lens surface area 3, in which the lens surface 20 does not exist. Figure 1 In the example shown, the non-lens surface area 3 has a notch structure V1 in which, when viewed along the optical axis C1, the boundary B1 is recessed inward relative to the lens surface area 2. That is, when viewed along the optical axis C1, a portion of the periphery of the lens surface area 2 is recessed (refer to FIG. Figure 2 As used herein, the “optical axis C1 ” refers to, for example, an axis passing through a vertex P1 of a first lens surface 21 (to be described later) and an image point J1A of the first lens surface 21 . Figure 1 It is a perspective view illustrating the appearance of the lens 1 . Figure 2 is a front view of the lens 1 when viewed along the optical axis C1.

[0037] The lens surface 20 includes: a first lens surface 21, which is a convex lens surface and is configured as a convex curved surface CV1 having a vertex P1; a second lens surface 22, which is an aspherical surface and has a curvature different from that of the first lens surface 21. The image point J1B of the second lens surface 22 is formed at the same spatial coordinates as the image point J1A of the first lens surface. That is, the axes 211 and 222 of the principal rays both pass through the image point J1 of the lens 1 (reference Figure 1). The axis 222 of the principal ray relative to the second lens surface 22 is defined as non-coaxial with the axis 211 of the principal ray relative to the first lens surface 21. As used herein, the "axis of the principal ray" refers to an axis passing through the center of the lens surface, the image point J1A of the first lens surface 21, and the image point J1B of the second lens surface 22. The first lens surface 21 and the second lens surface 22 have different principal ray axes from each other. Note that in Figure 4 , for convenience, the photosensitive element 5 is illustrated at the image point J1A of the first lens surface 21 and the image point J1B of the second lens surface 22. That is, if the lens 1 is applied to the optical sensor system 100, both the axis 211 of the principal ray relative to the first lens surface 21 and the axis 222 of the principal ray relative to the second lens surface 22 pass through the photosensitive element 5. Note that Figure 1 The image points J1, J1A, and J1B shown in FIG are exemplary image points relative to an object located at a specific position, and the positions of these image points may be shifted depending on the distance from the lens 1 to the object. However, even if these image points are shifted, the principal ray relative to the axis 222 of the second lens surface 22 and the principal ray relative to the axis 211 of the first lens surface 21 still maintain at least a non-coaxial relationship.

[0038] Furthermore, in the following description, the second lens surface 22 is interposed between the first lens surface 21 and the non-lens surface area 3 to extend along at least a portion of a boundary B1 between the lens surface area 2 and the non-lens surface area 3 when viewed along the optical axis C1 passing through the vertex P1.

[0039] According to this configuration of the lens 1, the first lens surface 21 and the second lens surface 22 are arranged so that the axis 222 of the principal ray relative to the second lens surface 22 is non-coaxial with the axis 211 of the principal ray relative to the first lens surface 21. Therefore, the lens 1 achieves an advantage of helping to more accurately converge incident light even if the incident light has traveled a distance falling within a wider range before being incident on the lens 1.

[0040] like Figure 5As shown, an optical sensor system 100 according to one aspect includes a light projecting unit 4, the aforementioned lens 1 (light receiving lens 7), and a photosensor 5. The light projecting unit 4 projects a laser beam Op1 toward an object to be measured Ob1. The lens 1 focuses light Op2 reflected from the object to be measured Ob1. The photosensor 5 receives the light focused by the lens 1 and converts the light into an electrical signal. The photosensor 5 is configured such that a light receiving axis 51 of the photosensor 5 coincides with the optical axis C1. The light projecting axis 41 and the light receiving axis 51 of the light projecting unit 4 are parallel to each other relative to the optical axis C1. As used herein, if something is "parallel to" something else, the two objects are not necessarily completely parallel to each other; for example, an angle of approximately ±10 degrees may be formed between the two objects. This configuration provides the advantage of providing an optical sensor system 100 including a lens 1 that helps more accurately focus incident light, even if the incident light has traveled a distance within a wider range before entering the lens 1.

[0041] (detail)

[0042] (Overall structure)

[0043] Now refer to Figures 1 to 8 B of the present invention describes in detail the lens 1 and the optical sensor system 100 (TOF sensor 200) according to this embodiment. In the following description, the X-axis, Y-axis, and Z-axis are defined as follows with respect to the lens 1. Specifically, the direction parallel to the optical axis C1 passing through the vertex P1 of the first lens surface 21 is defined herein as the Z-axis direction. In addition, when viewed along the optical axis C1 (Z-axis direction), the non-lens surface area 3, the second lens surface 22, and the first lens surface 21 are arranged one above the other in an arrangement direction A1 (reference direction Figure 2 ) is defined herein as the Y-axis direction. The X-axis direction is perpendicular to each of the Y-axis direction and the Z-axis direction defined in this manner.

[0044] The lens 1 is generally formed as a plano-convex lens, for example. When viewed as a whole, one surface of the lens 1 on the positive side of the Z axis is generally convex toward the positive side of the Z axis, while the other surface of the lens 1 on the negative side of the Z axis is generally flat. However, this is merely an example and should not be construed as limiting. Alternatively, the other surface of the lens 1 on the negative side of the Z axis does not necessarily have a flat shape, but may also be generally convex toward the negative side of the Z axis. The lens 1 has a thickness in the Z-axis direction.

[0045] Figure 2 is a front view of the lens 1 when viewed from the positive side of the Z axis, Figure 1 A more schematic version of the lens 1 is shown. In front view, the lens 1 is generally in the shape of a perfect circle. However, the overall shape of the lens 1 in front view is not limited to any particular shape, but may also be in the shape of an elongated racetrack rather than a circle.

[0046] like Figure 1 and Figure 2 As shown, the lens 1 comprises a lens surface area 2 and a non-lens surface area 3. Figure 2 It can be seen that, when viewed from the positive side of the Z axis, there is a substantially arc-shaped boundary B1 between the lens surface region 2 and the non-lens surface region 3 .

[0047] The lens surface region 2 has a lens surface 20 that collects light incident on the lens surface 20 from the positive side of the Z axis. If the lens 1 is applied to the TOF sensor 200, the “incident light” used herein may include the incident light incident on the surface of the measurement object Ob1 (i.e., the reflective surface of the measurement object Ob1; refer to FIG. 1 ). Figure 5 ) is reflected from the lens 1. Note that the light incident on the lens 1 is not limited to the reflected light.

[0048] In short, the lens surface 20 may be a light incident surface 20A (refer to Figure 4 A and Figure 4 On the other hand, the other surface opposite to the lens surface 20 (ie, the surface of the lens 1 on the negative side of the Z axis) may be a light exit surface 20B (refer to Figure 4 A and Figure 4 B). The optical axis C1 intersects the light exit surface 20B at a right angle.

[0049] The lens surface 20 includes a first lens surface 21 which is a convex lens surface and a second lens surface 22 which is an aspherical surface. In other words, the lens 1 is a segmented lens in which the lens surface 20 is segmented into the first lens surface 21 and the second lens surface 22. Note that in this embodiment, as an example, it is assumed that the first lens surface 21 is aspherical.

[0050] The first lens surface 21 is configured as a convex curved surface CV1 including a vertex P1. In this regard, Figure 6 A shows a plano-convex lens 1A having a convex surface CV1. The lens 1 includes a first lens surface 21. Figure 6 A shows a portion of the convex surface CV1 of the plano-convex lens 1A.

[0051] The first lens surface 21 can have a convex surface CV1 defined by the following lens equation (1), where z is the lens depression depth in a direction parallel to the optical axis C1 (i.e., the Z-axis direction), C is the curvature, k is the cone constant, r is the radius coordinate, and αi is the aspheric coefficient.

[0052]

[0053] When classified according to the distance to the measurement object Ob1, the first lens surface 21 is a "long-distance" lens surface. The first lens surface 21 is applicable not only to long distances but also to medium distances. In the following description, the first lens surface 21 will sometimes be referred to as "long-distance lens surface F1" hereinafter (refer to Figure 4 A and Figure 4 In the present embodiment, “medium to long distance” is assumed to refer to the distance L1 (refer to Figure 4 A) falls within the range of approximately 500 mm to 5,000 mm. In other words, the first lens surface 21 can be configured as a surface that can converge the reflected light Op2 reflected from the measurement object Ob1 located at a distance of approximately 5,000 mm from the lens 1 to such an extent that the amount of light received at the photosensitive element 5 is not less than the lower limit value (threshold value). As used herein, the "lower limit value" refers to a threshold value set as a value for distance measurement by the TOF sensor 200 and can be, for example, a received light amount of 10 μW. In addition, the numerical value of 5,000 mm is an exemplary reference for the "furthest distance" of the "long distance" and should not be interpreted as strictly limiting the "furthest distance" of the "long distance".

[0054] The second lens surface 22 has a different curvature from the first lens surface 21. The second lens surface 22 includes a cylindrical lens surface 220 (refer to Figure 1 In this regard, Figure 6 B illustrates a plano-convex cylindrical lens 1B having an aspherical surface S1 (ie, a cylindrical lens surface 220). The lens 1 includes a second lens surface 22 Figure 6 FIG. 1B shows a portion of the aspherical surface S1 (i.e., the cylindrical lens surface 220) of the plano-convex cylindrical lens 1B. Figure 6 In B, the area of ​​the cylindrical lens surface 220 of the cylindrical lens 1B serving as the second lens surface 22 is used as a reference. Note that the "cylindrical lens 1B" used herein does not necessarily have this semi-cylindrical shape, but can also refer to a lens having a lens surface configured as a portion of a hyperbolic surface. In short, the aspherical surface S1 is not necessarily a strictly semi-cylindrical curved surface.

[0055] The second lens surface 22 may have an aspheric surface S1 defined by the following lens equation (2), where z is the lens sag depth in a direction parallel to the optical axis C1 (i.e., the Z-axis direction), C is the curvature, k is the cone constant, and y is the Y coordinate. As described above, the curvature C of the aspheric surface S1 of the second lens surface 22 is different from the curvature C of the first lens surface 21. Optionally, the lens equation (2) may include an aspheric coefficient.

[0056]

[0057] The second lens surface 22 is a close-range lens surface with respect to the distance to the measurement object Ob1. In the following description, the second lens surface 22 will sometimes be referred to as "super-close-range lens surface F2" hereinafter (refer to Figure 4 A and Figure 4 In this embodiment, the “ultra-close distance” is assumed to refer to the distance L1 (refer to the distance L1 between the lens 1 (for example, the vertex P1 of the first lens surface 21) and the measurement object Ob1. Figure 4 B) falls within the range of approximately 50 mm to 500 mm. In other words, the first lens surface 21 can be configured to converge reflected light Op2 reflected from the measurement object Ob1 located approximately 50 mm from the lens 1 to such an extent that the amount of light received by the photosensor 5 is no less than the lower limit value (threshold value). As used herein, the value of 50 mm is an exemplary reference to the "closest distance" of the "ultra-close distance" and should not be interpreted as strictly limiting the "closest distance" of the "ultra-close distance."

[0058] The ratio of the area occupied by the second lens surface 22 to the total area of ​​the lens surface 20 is smaller than the ratio of the area occupied by the first lens surface 21 to the total area of ​​the lens surface 20 .

[0059] Figure 3 : is a lens sag diagram showing the lens sag depths of the convex curved surface CV1 and the aspherical surface S1 of the lens 1 measured in a direction parallel to the optical axis C1 (Z-axis direction), with the vertex P1 drawn as the origin "0". Figure 3 In FIG. 1 , a cross × indicates the position of the generatrix D1 (which extends in the X-axis direction) on the aspherical surface S1 (cylindrical lens surface 220) of the second lens surface 22. Note that Figure 3 , the lens sag depth on the ordinate is normalized by the thickness of lens 1 (to fall within the range from “0” to “-1”), and the abscissa (Y coordinate) is normalized by the diameter of lens 1 (to fall within the range from “-1” to “-1”).

[0060] The generatrix direction (ie, the direction without curvature or power) relative to the cylindrical lens surface 220 is parallel to the X axis. As used herein, "generatrix D1" refers to the direction of the cylindrical lens surface 220. Figure 6 As shown in B, it is drawn as a (non-solid) imaginary line extending in the generatrix direction and passing through the point on the aspheric surface S1 that is located at the farthest position from the plane on the opposite side of the aspheric surface S1. Figure 1) intersects (for example, at a right angle) with a configuration direction A1 in which the non-lens surface area 3, the second lens surface 22, and the first lens surface 21 are configured one above the other when viewed along the optical axis C1.

[0061] The portion serving as the second lens surface 22 of the lens 1 (which forms Figure 6 The portion of the aspheric surface S1 shown in B) corresponds to the normalized diameter of the lens 1 Figure 3 The Y coordinate range shown is from 0.35 to 0.48. That is, the second lens surface 22 is configured not to include the generatrix D1 relative to the cylindrical lens surface 220. In the lens 1, the second lens surface 22 is configured to be adjacent to the non-lens surface area 3. Note that by Figure 3 The Y coordinate value of 0.74, which is normalized by the diameter of the lens 1 in FIG. 1 , indicates the position of a light projection axis 41 of a light projection unit 4 (to be described later).

[0062] In addition, if Figure 3 As shown, the second lens surface 22 is configured to shift a generating line D1 with respect to the cylindrical lens surface 220 to the positive side of the Y axis with respect to the vertex P1 of the first lens surface 21 .

[0063] The non-lens surface area 3 is an area where the lens surface 20 does not exist. In this embodiment, the peripheral portion of the lens 1 on the positive side of the Y axis is cut off. Specifically, the lens 1 is provided with a through hole H1, which passes through the peripheral portion of the lens 1 along the Z axis direction. When viewed along the optical axis C1 (along the Z axis direction), the through hole H1 opens on the outside of the lens 1. In other words, the non-lens surface area 3 has a notch structure V1, wherein the boundary B1 is recessed inwardly relative to the lens surface area 2 when viewed along the optical axis C1. Figure 1 In the example shown, a substantially semicircular through-hole H1 is provided through the peripheral portion of the lens 1 on the positive side of the Y axis. When viewed along the optical axis C1, the boundary B1 is recessed in a substantially arcuate shape toward the vertex P1 (i.e., in a direction corresponding to the negative side of the Y axis).

[0064] In this embodiment, the first lens surface 21 has an axis 211 of a principal ray passing through the center of the first lens surface 21 and pointing to the image point J1A of the first lens surface 21 (refer to Figure 1 The second lens surface 22 has an axis 222 of a principal ray passing through the center of the second lens surface 22 and pointing to the image point J1B of the second lens surface 22 (reference Figure 1 ). Note that the image point J1A of the first lens surface 21 and the image point J1B of the second lens surface 22 are formed at the same spatial coordinates and correspond to the image point J1 of the lens 1. That is, the axes 211 and 222 of the principal rays both pass through the image point J1 of the lens 1 (refer to Figure 1In this embodiment, the axis 222 of the principal ray relative to the second lens surface 22 is configured to be non-coaxial with the axis 211 of the principal ray relative to the first lens surface 21, as shown in FIG. Figure 1 Furthermore, the second lens surface 22 is interposed between the first lens surface 21 and the non-lens surface region 3 so as to extend along at least a portion of a boundary B1 between the lens surface region 2 and the non-lens surface region 3 when viewed along the optical axis C1 passing through the vertex P1 (refer to Figure 2 ). For example, when viewed along the optical axis C1, the second lens surface 22 is formed into a crescent shape extending along at least a portion of the boundary B1. Note that Figure 2 In the schematic lens 1 shown, the second lens surface 22 formed in a crescent shape is configured to extend along the boundary B1 from one end B11 to the other end B12 of the arc-shaped boundary B1 in the X-axis direction. Alternatively, the second lens surface 22 can also be configured to extend along the boundary B1 inside the two end portions B11 and B12, as shown in FIG. Figure 1 As shown. The second lens surface 22 is not necessarily crescent-shaped, but may also be half-moon or rectangular. However, forming the second lens surface 22 in such a crescent shape as in the present embodiment makes it easier to reduce the ratio of the area occupied by the second lens surface 22 to the total area of ​​the lens surface 20. That is, light needs to travel a greater distance in the case of "long distance" than in the case of "ultra-close distance", thus making it easier for the reflected light Op2 to diffuse when propagating through the air. Therefore, in order to converge the reflected light Op2 from a long distance with maximum efficiency, the area occupied by the first lens surface 21 (long-distance lens surface F1) is preferably as large as possible. Therefore, reducing the area occupied by the second lens surface 22 allows the area occupied by the first lens surface 21 (long-distance lens surface F1) to be increased, thereby enabling the incident light to be converged more accurately.

[0065] As can be seen, lens 1 includes a long-distance lens surface F1 and an ultra-close-distance lens surface F2, thereby achieving the advantage of more accurately converging incident light, even if the incident light has traveled a distance falling within a wider range before entering lens 1, for example, from measurement object Ob1. Furthermore, the generatrix direction (X-axis direction) relative to second lens surface 22 intersects (e.g., at right angles) with arrangement direction A1, in which non-lens surface region 3, second lens surface 22, and first lens surface 21 are arranged one above the other when viewed along optical axis C1, thereby facilitating the realization of second lens surface 22 that allows incident light to be more accurately converged. Furthermore, second lens surface 22 includes cylindrical lens surface 220, thereby allowing incident light to be imparted with appropriate viewing angle characteristics. This makes it easier for incident light to reach photosensor 5 (described later). In particular, second lens surface 22 is configured so as not to include generatrix D1 relative to cylindrical lens surface 220, thereby facilitating the realization of second lens surface 22 that allows incident light to be more accurately converged.

[0066] In the present embodiment, the second lens surface 22 is located at a lower level than the first lens surface 21 in the Z-axis direction in a manner recessed relative to the first lens surface 21 (refer to Figure 1 and Figure 3 ). In other words, there is a level difference between the first lens surface 21 and the second lens surface 22 in the Z-axis direction, and the second lens surface 22 is located at a level lower than the first lens surface 21 in the Z-axis direction by the level difference. However, this is merely an example and should not be construed as limiting. Alternatively, such a level difference may be eliminated. Still alternatively, the second lens surface 22 may even be located at a higher level than the first lens surface 21 in the Z-axis direction in a manner that is convex relative to the first lens surface 21.

[0067] like Figure 5 As shown, the TOF sensor 200 includes a light projecting unit 4, a light receiving lens 7 (lens 1), a light sensitive element 5, a light projecting circuit 101, a light receiving circuit 102, a control unit 103, and an output unit 104. In addition, the TOF sensor 200 also includes a single or multiple mounting boards (such as printed circuit boards) on which the light projecting unit 4, the light receiving lens 7, the light sensitive element 5, the light projecting circuit 101, the light receiving circuit 102, the control unit 103, the output unit 104, and other components are mounted, and a housing 105 for accommodating or holding these components (see FIG. 1 ). Figure 5 ).

[0068] The light projecting unit 4 projects a laser beam Op1 toward the object Ob1 to be measured. The light projecting unit 4 includes a light projecting lens 401, a light projecting element 402 (laser diode) serving as a light source, and a housing 403 (see FIG. 4 ) that houses these components. Figure 4 A and Figure 4B). The light-emitting element 402 is electrically connected to the light-emitting circuit 101 and emits the laser beam Op1 according to the driving instruction given by the light-emitting circuit 101. The light-emitting lens 401 is arranged to face the light-emitting element 402. The light-emitting unit 4 has a light-emitting surface 4A (refer to Figure 4 A and Figure 4 (B), laser beam Op1 is emitted to the outside world through light exit surface 4A. Light exit surface 4A is assumed to be, for example, the lens surface of light projection lens 401 located on the positive side of the Z axis. Light projection lens 401 is disposed within housing 403 so that light exit surface 4A is exposed. Light projection axis 41 of light projection unit 4 intersects light exit surface 4A at a substantially right angle.

[0069] In the present embodiment, the light exit surface 4A is located at substantially the same position as the vertex P1 of the first lens surface 21 in the Z-axis direction.

[0070] The wavelength of the laser beam Op1 is not limited to any specific value. In this embodiment, the TOF sensor 200 is assumed to be used, for example, in a transport process at a facility (such as a factory). Therefore, in order to allow a user (such as a supervisor at the facility) to visually inspect the projection spot of the laser beam Op1, the laser beam Op1 is assumed to be visible light with a wavelength of, for example, around 660 nm, falling within the red portion of the spectrum.

[0071] Note that in this embodiment, for example, the projection spot formed by the laser beam Op1 projected from the light projecting unit 4 on a plane (XY plane) perpendicular to the projection axis 41 is assumed to have a true circular cross-sectional shape. That is, if the laser beam Op1 is projected perpendicularly from the light projecting unit 4 onto the surface (plane) of the measurement object Ob1, a nearly true circular projection spot is assumed to be formed on the surface.

[0072] The light projecting circuit 101 outputs a drive signal to the light projecting element 402 according to the control command from the control unit 103 and adjusts the emission intensity and emission time of the laser beam Op1. The light projecting element 402 emits (projects) a pulsed light beam (i.e., the laser beam Op1) according to the drive signal.

[0073] The light receiving lens 7 is the lens 1 described above. The light receiving lens 7 is disposed in the housing 105 with the lens surface 20 exposed so that the light Op2 reflected from the object Ob1 is incident on the light receiving lens 7. The light receiving lens 7 collects the light Op2 reflected from the object Ob1.

[0074] like Figure 4 A and Figure 4As shown in Figure B, the photosensitive element 5 is arranged behind the light-receiving lens 7 (i.e., on the negative side of the Z axis relative to the light-receiving lens 7). The photosensitive element 5 receives the light that has been converged by the light-receiving lens 7 to convert the light into an electrical signal (photoelectric signal). The photosensitive element 5 can be implemented as, for example, a photodiode. The photosensitive element 5 is electrically connected to the light-receiving circuit 102 to output a photoelectric signal to the light-receiving circuit 102. The light-receiving axis 51 of the photosensitive element 5 can, for example, intersect with the photosensitive plane of the photosensitive element 5 at a right angle. The photosensitive element 5 is configured to face the light-emitting surface 20B of the light-receiving lens 7 so that the light-receiving axis 51 passes through the vertex P1 of the first lens surface 21 of the light-receiving lens 7 (in other words, so that the light-receiving axis 51 is consistent with the optical axis C1). The light-receiving axis 51 intersects the light-emitting surface 20B at a right angle.

[0075] The photosensitive element 5 is arranged at the focal position of the first lens surface 21. As described above, the second lens surface 22 is configured so that the generating line D1 relative to the cylindrical lens surface 220 is shifted to the positive side of the Y axis relative to the vertex P1 of the first lens surface 21. Therefore, the focal position of the second lens surface 22 is shifted to the positive side of the Y axis relative to the focal position of the first lens surface 21 (that is, the position of the photosensitive element 5).

[0076] The higher the frequency response characteristics of the TOF sensor 200, the higher the distance detection accuracy of the TOF sensor 200. This is why the smaller the size of the photosensitive element 5, the better. In this embodiment, the photosensitive element 5 is a microscopic photosensitive element, and the width or diameter of its photosensitive surface is equal to or less than, for example, 1 mm. The light projection axis 41 and the light receiving axis 51 of the light projecting unit 4 are parallel to each other relative to the optical axis C1. In this case, the light projection axis 41 and the light receiving axis 51 do not necessarily need to be completely parallel to each other; instead, they may form an angle of, for example, approximately ±10 degrees between them.

[0077] Furthermore, in this embodiment, the light projection axis 41 and the light receiving axis 51 are not coaxial with each other.

[0078] The light receiving circuit 102 may include, for example, an A / D converter circuit that converts an analog photoelectric signal indicating the amount of received light provided by the photosensor 5 into a digital photoelectric signal to output the digital photoelectric signal to the control unit 103 .

[0079] Control unit 103 comprises a computer system including one or more processors and memory. At least some of the functions of control unit 103 are performed by having the computer system's processor execute a program stored in the computer system's memory. The program may be pre-stored in the memory. Alternatively, the program may be downloaded via a telecommunications line such as the Internet, or distributed after being stored on a non-transitory storage medium such as a memory card. Control unit 103 is electrically connected to light projecting circuit 101, light receiving circuit 102, and output unit 104 to control these components 101, 102, and 104.

[0080] Based on the photoelectric signal supplied from the light receiving circuit 102, the control unit 103 calculates the amount of time between the time when the laser beam Op1 (pulsed beam) is emitted from the light projecting unit 4 and the time when the reflected light Op2 generated by the laser beam Op1 reflecting off the object Ob1 is received by the photosensor 5. In other words, the control unit 103 calculates the amount of time it takes for the light beam to travel back and forth between the TOF sensor 200 and the object Ob1. Based on the calculation result, the control unit 103 then calculates distance data (distance measurement result) indicating the distance to the object Ob1, and causes the output unit 104 to output the distance data to an external device.

[0081] Meanwhile, in this embodiment, the light projecting unit 4 is placed within the non-lens surface area 3. In this embodiment, the housing 403 of the light projecting unit 4 has a generally cylindrical shape, with the central axis of the cylinder of the housing 403 intersecting the light exit surface 4A of the light projecting lens 401 at a substantially right angle. The central axis of the cylinder of the housing 403 substantially coincides with the light projection axis 41 of the light projecting unit 4. Furthermore, to facilitate the fitting of the housing 403 within the non-lens surface area 3, the non-lens surface area 3 has a shape substantially identical to that of the housing 403 when viewed in the Z-axis direction. The non-lens surface area 3 has a notch structure V1. Therefore, when viewed in the Z-axis direction, the peripheral edge of the housing 403 on the negative Y-axis side abuts the inner circumferential surface of the through-hole H1, contacting the inner circumferential surface of the through-hole H1. Alternatively, the peripheral edge of the housing 403 may not contact the inner circumferential surface of the through-hole H1, leaving a narrow gap between them. On the other hand, the peripheral edge portion of the housing 403 on the positive Y-axis side does not face the inner peripheral surface of the through hole H1 but is exposed outside the lens 1. Alternatively, the light projecting unit 4 may be held by the lens 1 by press-fitting the housing 403 into the through hole H1.

[0082] That is, the light projection unit 4 and its light projection axis 41 are stably positioned relative to the lens 1 by the non-lens surface area 3 having the notch structure V1. Alternatively, the light projection unit 4 can also be configured to be at least partially movable when placed within the non-lens surface area 3. In this case, the direction of movement is not limited to any particular direction. For example, the TOF sensor 200 can include a mechanism that allows the light projection unit 4 to be movable to form an inclined angle relative to the Z-axis direction. Alternatively, the TOF sensor 200 can include a mechanism that allows the light projection lens 401 to be movable in the Z-axis direction.

[0083] Instead of the through-hole H1 that penetrates the lens 1 in the Z-axis direction, the lens 1 may be provided with a recessed portion as the non-lens surface region 3 that does not penetrate the lens 1 in the Z-axis direction. The recessed portion may be configured such that one surface of the lens 1 on the negative Z-axis side is open and recessed toward the positive Z-axis side. Alternatively, the recessed portion may be configured such that the other surface of the lens 1 on the positive Z-axis side is open and recessed toward the negative Z-axis side. The light projecting portion 4 may be placed so as to fit tightly or loosely into the recessed portion (i.e., the non-lens surface region 3).

[0084] As can be seen, lens 1 is provided with a non-lens surface area 3. Therefore, placing light projecting portion 4 within non-lens surface area 3 brings light projection axis 41 and light receiving axis 51 closer together, thereby helping to reduce the size of the device (TOF sensor 200) in the X-axis and / or Y-axis directions while allowing lens 1 to focus incident light even more accurately. In particular, light projecting portion 4 is positioned adjacent to second lens surface 22, allowing photosensor 5 to receive a sufficient amount of light while reducing the area occupied by second lens surface 22. Consequently, this helps to increase the amount of reflected light Op2 received by photosensor 5.

[0085] In addition, in this embodiment, the generatrix D1 relative to the cylindrical lens surface 220 is between the light projection axis 41 and the light receiving axis 51. Figure 1 and Figure 3 As shown. That is, the second lens surface 22 is configured to be offset in the Y-axis direction toward the positive side of the Y-axis relative to the vertex P1 of the first lens surface 21. This allows the light-receiving lens 7 (lens 1) to even more accurately focus incident light from an "ultra-close distance." Consequently, the amount of light received by the photosensitive element 5 can be increased.

[0086] (Distance measurement characteristics of the lens)

[0087] Next, we will refer to Figure 7 The distance measurement characteristics of the lens 1 will be described. Figure 7This is a double logarithmic graph showing distance measurement characteristics (based on simulation results) of Lens 1 and a comparative example lens (hereinafter referred to as a "single lens"). As used herein, "single lens" refers to a plano-convex lens having only one lens surface. The single lens is a plano-convex lens having only the first lens surface 21 of Lens 1 and not the second lens surface 22 of Lens 1.

[0088] exist Figure 7 In the simulation, the abscissa indicates the detection distance [mm] from the lens (lens 1 or single lens) to the reflection point, and the ordinate indicates the amount of light received at the photosensitive element 5 [arbitrary unit (au)]. In this simulation, the measurement object Ob1 is not irradiated with a laser beam, and its reflected light is not received at the lens (lens 1 or single lens), but a reflection point is set on the measurement object Ob1, and the characteristics of the lens are inspected using the reflection point as a light source (such as a Lambertian light source).

[0089] exist Figure 7 In FIG, a dotted curve Q1 indicates distance measurement characteristics obtained using lens 1, and a solid curve Q2 indicates distance measurement characteristics obtained using a single lens.

[0090] from Figure 7 As can be seen from the distance measurement characteristics Q1 and Q2 shown, for "long distance," the amount of light received by the photosensitive element 5 using lens 1 is substantially equal to that received by the photosensitive element 5 using a single lens, and therefore, lens 1 has light-gathering accuracy nearly as high as that of a single lens. On the other hand, for "ultra-close distance," particularly when the detection distance falls within the range of approximately 50 mm to approximately 150 mm, the amount of light received by the photosensitive element 5 using lens 1 is significantly greater than that received by the photosensitive element 5 using a single lens, and therefore, it can be seen that lens 1 has light-gathering accuracy superior to that of a single lens.

[0091] It can be seen that the lens 1 converges incident light from a "long distance" toward the photosensitive element 5 via the entire lens surface 20 (i.e., the first lens surface 21 and the second lens surface 22), and converges incident light from a "very close distance" toward the photosensitive element 5 primarily via the second lens surface 22. In other words, the second lens surface 22 converges incident light from the "very close distance" toward the photosensitive element 5, refracting the incident light toward the negative side of the Y-axis to have a viewing angle.

[0092] (Application examples of TOF sensors)

[0093] Next, we will refer to Figure 8 A and Figure 8 B describes an application example of the TOF sensor 200 (optical sensor system 100 ).

[0094] Figure 8A is a conceptual diagram illustrating an application example 1 of the TOF sensor 200. In application example 1, the TOF sensor 200 is fixed on a ceiling surface 300 inside a facility such as a factory or a distribution warehouse. Directly below the TOF sensor 200, a carrier 400 such as a conveyor belt is arranged. The TOF sensor 200 measures the distance (in the vertical direction) to the large-sized workpiece 501, the medium-sized workpiece 502, and the small-sized workpiece 503 carried by the carrier 400. The TOF sensor 200 outputs the measurement results (distance data) to an external determination system. The external determination system can perform various types of processing based on the measurement results. The TOF sensor 200 can be a distance image sensor using the TOF method. In this case, the distance data can be distance image data. Optionally, the external determination system can perform inspection processing on the surface conditions of the workpieces 501, 502, and 503 based on the distance image data.

[0095] Figure 8 B is a conceptual diagram illustrating an application example 2 of the TOF sensor 200. In this application example 2, the TOF sensor 200 is also arranged inside a facility such as a factory or a distribution warehouse. The TOF sensor 200 is fixed by a fixing fixture located obliquely above the carrier 400 to measure the distance to the large-sized workpiece 501, the medium-sized workpiece 502, and the small-sized workpiece 503 in an oblique direction. The TOF sensor 200 outputs the measurement result (distance data) to, for example, an external determination system. The external determination system can perform a determination process for automatically determining the type of the workpieces 501, 502, and 503 based on the distance data obtained in the oblique direction. In particular, the external determination system uses only one TOF sensor 200, but can more accurately determine the type of a given workpiece by using the distance data obtained in the oblique direction.

[0096] (Variant 1-1)

[0097] Next, we will refer to Figure 9 A detailed description of the lens 1 according to this modification (modification 1-1) is given below. In the following description, any constituent element of the lens 1 according to this modification 1-1 having substantially the same function as the counterpart of the lens 1 according to the above exemplary embodiment will be denoted by the same reference numeral as the counterpart, and its description will be omitted herein as appropriate. Note that, Figure 9 A and Figure 2 is a front view of a schematic version of the lens 1 according to Modification 1-1 (when viewed from the Z-axis positive side).

[0098] The lens 1 according to this modification 1-1 and the lens 1 according to the above exemplary embodiment are also provided with a through hole H1 that penetrates the peripheral portion of the lens 1 in the Z-axis direction, and the non-lens surface area 3 also has a notch structure V1, wherein when viewed along the optical axis C1, the boundary B1 is recessed inwardly relative to the lens surface area 2. However, in the lens 1 according to this modification 1-1, the second lens surface 22 does not contact the boundary B1, which is different from the lens 1 according to the above exemplary embodiment. The second lens surface 22 can be configured as, for example, a cylindrical lens surface 220 and have a circular shape. Figure 9 In the example shown in A of FIG. 1 , the second lens surface 22 is located between the boundary B1 and the vertex P1 in a manner not to be in contact with the boundary B1 .

[0099] Note that the cylindrical lens surface 220 is not necessarily circular. Alternatively, the cylindrical lens surface 220 may be, for example, crescent-shaped or elliptical. For example, Figure 9 FIG. B shows lens 1, which is another example of variation 1-1. Figure 9 As shown in FIG. 1B , the cylindrical lens surface 220 may also be crescent-shaped.

[0100] (Variation 1-2)

[0101] Next, we will refer to 10A and Figure 10 B describes in detail the lens 1 according to this modification (Modification 1-2). In the following description, any constituent element of the lens 1 according to this Modification 1-2 having substantially the same function as the counterpart of the lens 1 according to the above exemplary embodiment will be denoted by the same reference numeral as the counterpart, and its description will be omitted herein as appropriate. Note that, Figure 10 A and Figure 10 B and Figure 2 is a front view of a schematic version of the lens 1 according to Modification 1-2 (when viewed from the Z-axis positive side).

[0102] In the above exemplary embodiment, lens 1 is provided with a through-hole H1 extending through the peripheral portion of lens 1 in the Z-axis direction, and non-lens surface region 3 has a notch structure V1 in which boundary B1 is recessed inward relative to lens surface region 2 when viewed along optical axis C1. In the lens 1 according to this modification 1-2, through-hole H1 (non-lens surface region 3) having a substantially circular opening is provided inside the peripheral portion of lens 1, which differs from the lens 1 according to the above exemplary embodiment. The opening of through-hole H1 (non-lens surface region 3) does not necessarily have to be circular, but may also have an elliptical shape, for example.

[0103] In the lens 1 according to this modification 1-2, as Figure 10As shown in FIG. 1A , through-hole H1 (non-lens surface region 3) is located between vertex P1 and the peripheral edge portion on the positive Y-axis side of lens surface region 2. When viewed in the Z-axis direction, boundary B1 between lens surface region 2 and non-lens surface region 3 and the inner peripheral edge of through-hole H1 are circular.

[0104] The lens 1 according to this modification 1-2 has two second lens surfaces 22, such as Figure 10 As shown in A. The two second lens surfaces 22 are respectively arranged adjacent to the through hole H1 (non-lens surface area 3) on the positive and negative sides of the Y axis. The two second lens surfaces 22 are both crescent-shaped and arranged symmetrically with each other in the Y axis direction. The two second lens surfaces 22 can be constructed as follows, for example Figure 6 B shows two surfaces of a common cylindrical lens surface 220 of a single plano-convex cylindrical lens 1B. Alternatively, the two second lens surfaces 22 can also be configured as corresponding parts of the cylindrical lens surfaces 220 of two different plano-convex lenses, for example.

[0105] exist Figure 10 In the example shown in FIG. 1A , the vertex P1 of the first lens surface 21 is adjacent to the second lens surface 22 on the Y-axis negative side of the through hole H1 (non-lens surface area 3 ). However, the vertex P1 of the first lens surface 21 is not necessarily adjacent to the second lens surface 22 on the Y-axis negative side.

[0106] In this modification 1-2, the generating line D1 relative to the cylindrical lens surface 220 is also preferably offset in the Y-axis direction relative to the vertex P1. In addition, in this modification 1-2, the two second lens surfaces 22 are preferably configured so as not to include the generating line D1 relative to the cylindrical lens surface 220.

[0107] In this modification 1-2, light projecting unit 4 may be placed inside through hole H1 (non-lens surface region 3). In this modification 1-2, generatrix D1 relative to cylindrical lens surface 220 may be located between light projection axis 41 and light receiving axis 51. In this modification 1-2, light projection axis 41 and light receiving axis 51 may not be coaxial with each other.

[0108] exist Figure 10 In the example illustrated in FIG. A, two second lens surfaces 22 are provided. Alternatively, as Figure 10 As shown in FIG. 1 , only one second lens surface 22 may be provided for the through hole H1 (non-lens surface region 3) on the positive or negative side of the Y axis. Figure 10 In the example shown in FIG. 1B , only one second lens surface 22 is provided for the through hole H1 (non-lens surface region 3 ) on the negative Y-axis side. However, the second lens surface 22 may be provided for the through hole H1 on the positive Y-axis side.

[0109] (Variant 2)

[0110] Next, we will refer to Figure 11 The lens 1 according to this modification (Modification 2) will be described in detail. In the following description, any constituent element of the lens 1 according to this Modification 2 having substantially the same function as its counterpart in the lens 1 according to the above exemplary embodiment will be denoted by the same reference numeral as the counterpart, and its description will be omitted herein as appropriate. Note that, Figure 11 as well as Figure 2 is a front view of a schematic version of the lens 1 according to Modification 2 (when viewed from the Z-axis positive side).

[0111] Modification 2 is a modified version of Modification 1-2. The through hole H1 (non-lens surface area 3) having a circular opening is configured so that the center of its opening coincides with the vertex P1 of the first lens surface 21 of the lens 1 according to the exemplary embodiment. In other words, the first lens surface 21 of the lens 1 according to this Modification 2 does not include the vertex P1 according to the exemplary embodiment. Note that in Figure 11 , vertex P1 is shown for reference.

[0112] In this second variation, the generatrix D1 relative to the cylindrical lens surface 220 substantially coincides with the vertex P1 in the Y-axis direction. In other words, according to this second variation, the generatrix D1 relative to the cylindrical lens surface 220 may intersect the light-receiving axis 51 and the optical axis C1, but may also be configured not to intersect the light-receiving axis 51 or the optical axis C1. In this second variation, the two second lens surfaces 22 are preferably configured so as not to include the generatrix D1 relative to the cylindrical lens surface 220.

[0113] In this variant 2, the light projection portion 4 can also be placed inside the through hole H1 (non-lens surface area 3). However, in this variant 2, the light projection axis 41 and the light receiving axis 51 can be defined as being coaxial with each other, which is different from the above-mentioned exemplary embodiment and variants 1-1 and 1-2. That is, in this variant 2, the light projection axis 41 can also be coaxial with the optical axis C1. The generatrix D1 relative to the cylindrical lens surface 220 can intersect with the light projection axis 41 in this variant 2, but can also be defined as not intersecting with the light projection axis 41.

[0114] (Variant 3)

[0115] Next, we will refer to Figure 12 A and Figure 12 B describes in detail the lens 1 according to this modification (Modification 3). In the following description, any constituent element of the lens 1 according to this Modification 3 having substantially the same function as the counterpart of the lens 1 according to the above exemplary embodiment will be denoted by the same reference numeral as the counterpart, and its description will be omitted herein as appropriate. Note that, Figure 12 A and Figure 2 is a front view of a schematic version of the lens 1 according to Modification 3 (when viewed from the Z-axis positive side).

[0116] The lens 1 according to this modification 3 and the lens 1 according to the above exemplary embodiment are further provided with a through hole H1 penetrating the peripheral portion of the lens 1 in the Z-axis direction, and the non-lens surface area 3 also has a notch structure V1, wherein when viewed along the optical axis C1, the boundary B1 is recessed inwardly relative to the lens surface area 2. However, in the lens 1 according to this modification 3, the second lens surface 22 includes a plurality of cylindrical lens surfaces 220, which is different from the lens 1 according to the above exemplary embodiment. Figure 12 In the example shown in FIG. 1A , three cylindrical lens surfaces 220 are provided.

[0117] The three cylindrical lens surfaces 220 are sequentially arranged adjacent to each other from the boundary B1 toward the negative side of the Y axis. In the following description, the three cylindrical lens surfaces 220 will be referred to as "cylindrical lens surfaces 220A, 220B, and 220C" from the boundary B1 toward the negative side of the Y axis.

[0118] For example, each of the cylindrical lens surfaces 220A, 220B, and 220C may be crescent-shaped. However, these cylindrical lens surfaces 220A, 220B, and 220C are defined so that their occupied areas gradually increase in this order relative to the lens surface 20. The crescent-shaped cylindrical lens surfaces 220A, 220B, and 220C are formed continuously in this order. The ends of each of these crescent-shaped cylindrical lens surfaces 220A, 220B, and 220C in the X-axis direction are located at substantially the same points as the ends B11 and B12 of the arc-shaped boundary B1 in the X-axis direction.

[0119] Note that these cylindrical lens surfaces 220A, 220B, and 220C are not necessarily crescent-shaped. Alternatively, at least one of the cylindrical lens surfaces 220A, 220B, and 220C may also be, for example, half-moon-shaped or rectangular extending along the X-axis. For example, Figure 12 FIG. B illustrates another example of the lens 1 according to the modification 3. Figure 12 As shown in FIG. 8B , the cylindrical lens surfaces 220A and 220B may each be in a substantially rectangular shape extending along the X-axis, and the cylindrical lens surface 220C may be in a substantially half-moon shape.

[0120] In the lens 1 according to this modification 3, the plurality of cylindrical lens surfaces 220 have focal points at correspondingly different positions in the arrangement direction A1 (Y-axis direction). For example, the cylindrical lenses forming cylindrical lens surface 220A, the cylindrical lenses forming cylindrical lens surface 220B, and the cylindrical lenses forming cylindrical lens surface 220C are different from one another. In other words, the generatrix D1 with respect to the cylindrical lens surfaces 220A, 220B, and 220C is different from one another. Furthermore, the cylindrical lens surfaces 220A, 220B, and 220C are formed so as to have focal points at correspondingly different positions.

[0121] In short, in this third variation, the ultra-close lens surface F2 is subdivided. For example, the cylindrical lens surface 220A is configured as the ultra-close lens surface F2 used when the distance to the object Ob1 is approximately 50 mm. For example, the cylindrical lens surface 220B is configured as the ultra-close lens surface F2 used when the distance to the object Ob1 is approximately 100 mm. For example, the cylindrical lens surface 220C is configured as the ultra-close lens surface F2 used when the distance to the object Ob1 is approximately 150 mm. In other words, in this variation, the closer a given cylindrical lens surface 220 is located to the non-lens surface area 3, the shorter the distance to the object Ob1 from which the reflected light Op2 to be converged by the cylindrical lens surface 220 originates.

[0122] The configuration according to this variation 3 can more accurately focus incident light from a distance falling within a wider range.

[0123] (Variant 4)

[0124] Next, we will refer to Figure 13 A. Figure 13 B. Figure 14 A and Figure 14 B describes in detail the lens 1 according to this modification (Modification 4). In the following description, any constituent element of the lens 1 according to this Modification 4 having substantially the same function as its counterpart in the lens 1 according to the above exemplary embodiment will be denoted by the same reference numeral as the counterpart, and its description will be appropriately omitted herein. Note that, Figure 13 A and Figure 14 A and Figure 2 is a front view of a schematic version of the lens 1 according to Modification 4 (when viewed from the Z-axis positive side). Figure 13 B is along Figure 13 A is a cross-sectional view taken along plane II. Figure 14 B is along Figure 14 A is a cross-sectional view taken along plane II-II.

[0125] In the lens 1 according to this modification 4, at least one of the first lens surface 21 or the second lens surface 22 has a Fresnel structure X1, which is different from the lens 1 according to the above exemplary embodiment. Note that in this modification 4, the non-lens surface area 3 has a notch structure V1, which is different from the lens 1 according to the above exemplary embodiment (referring to FIG. 1 ). Figure 2 ), the boundary B1 is recessed more deeply toward the inside of the lens surface region 2 (ie, toward the negative side of the Y axis).

[0126] In the embodiment according to the present variation 4 Figure 13 In the lens 1 shown in FIG. 1A , the first lens surface 21 and the second lens surface 22 have a first Fresnel structure X11 ( X1 ) and a second Fresnel structure X12 , respectively.

[0127] Specifically, the first lens surface 21 has a first Fresnel structure X11, in which the first lens surface 21 is divided into a plurality of substantially concentric regions as in a so-called "Fresnel lens", and has a structure as shown in FIG. Figure 13 A and Figure 13 The second lens surface 22 also has a second Fresnel structure X12, wherein the second lens surface 22 is divided into a plurality of substantially concentric regions, as in a Fresnel lens, and has a Figure 13 A and Figure 13 B shows the serrated cross section.

[0128] Meanwhile, in another embodiment according to this variation 4 Figure 14 In the lens 1 shown in FIG. 1A , only one of the first lens surface 21 or the second lens surface 22 (i.e., the first lens surface 21 ) has the Fresnel structure X1 (the first Fresnel structure X11 ). Alternatively, of the first lens surface 21 and the second lens surface 22 , only the second lens surface 22 may have the Fresnel structure X1.

[0129] It can be seen that in the configuration according to this modification 4, at least one of the first lens surface 21 or the second lens surface 22 has the Fresnel structure X1 , thereby making it easier to reduce the lens thickness of the lens 1 and contributing to cutting the material cost of the lens 1 .

[0130] (Variant 5)

[0131] Next, we will refer to Figure 15 A. Figure 15 B and Figure 15C. The lens 1 according to this modification (Modification 5) is described in detail. In the following description, any constituent element of the lens 1 according to this Modification 5 having substantially the same function as the counterpart of the lens 1 according to the above exemplary embodiment will be denoted by the same reference numeral as the counterpart, and its description will be appropriately omitted herein. Note that, Figure 15 A and Figure 2 is a front view of a schematic version of the lens 1 according to Modification 5 (when viewed from the Z-axis positive side).

[0132] In the lens 1 according to this modification 5, the second lens surface 22 includes an annular lens surface 221 (refer to Figure 15 A), which is different from the lens 1 according to the exemplary embodiment. In this regard, Figure 15 B shows a plano-convex annular lens 1C having an aspherical surface S1 (annular lens surface 221). The lens 1 includes a second lens surface 22 Figure 15 FIG. 1B shows a portion of the aspherical surface S1 (annular lens surface 221) of the plano-convex annular lens 1C. In the annular lens 1C, for example, the curvature of a cross section taken along the YZ plane and the curvature of another cross section taken along the XZ plane (refer to FIG. Figure 15 The parts marked as "having curvature" in B are different from each other. Figure 15 In FIG. 1B , a region of the annular lens surface 221 of the annular lens 1C that can be used as the second lens surface 22 is shown. Figure 15 In B, the light projection axis 41 and the light receiving axis 51 are shown for reference to indicate where the light projection axis 41 and the light receiving axis 51 are located relative to the annular lens surface 221 and the vertex P2 of the annular lens surface 221 when the lens 1 according to this variation 5 is applied to the TOF sensor 200.

[0133] The second lens surface 22 (annular lens surface 221) and the second lens surface 22 (cylindrical lens surface 220) according to the exemplary embodiment may have, for example, a crescent shape to reduce the area occupied by the second lens surface 22. According to the above exemplary embodiment, the relative position of the second lens surface 22 (annular lens surface 221) with respect to the non-lens surface area 3 and the first lens surface 21 is substantially the same as the relative position of the second lens surface 22 (cylindrical lens surface 220) according to the exemplary embodiment.

[0134] In this modification 5, the vertex P2 of the annular lens surface 221 is preferably set to be 1 / 4 of the vertex P1 (reference Figure 1 and Figure 2 The vertex P2 of the annular lens surface 221 can be set between the light-projecting axis 41 and the light-receiving axis 51, as shown in FIG. Figure 15As shown in B. In this modification 5, the second lens surface 22 is preferably configured not to include the vertex P2 of the annular lens surface 221 .

[0135] Figure 15 C illustrates a cylindrical lens 1B to make it easier to compare the cylindrical lens 1B with the toroidal lens 1C. In the cylindrical lens 1B, a cross section taken along the XZ plane has no curvature, as shown in FIG. Figure 15 As shown in C.

[0136] It can be seen that in the configuration according to this modification 5, the second lens surface 22 includes the annular lens surface 221 , thereby making it easier to implement the second lens surface 22 that can more accurately concentrate incident light.

[0137] Note that the second lens surface 22 is not limited to the cylindrical lens surface 220 and the annular lens surface 221 , but may also include an anamorphic aspheric surface or include an xy polynomial plane.

[0138] (Variant 6)

[0139] Will refer to Figure 16 and Figure 17 The light projecting unit 4 of the optical sensor system 100 (TOF sensor 200) according to this modification (Modification 6) will be described. In the following description, any constituent elements of the optical sensor system 100 according to this Modification 6 that have the same functions as their counterparts in the optical sensor system 100 according to the above-described embodiment will be denoted by the same reference numerals as those of the counterparts, and description thereof will be omitted herein as appropriate.

[0140] In the optical sensor system 100 according to the exemplary embodiment described above, the cross section of the light projection spot formed by the laser beam Op1 projected from the light projection section 4 onto the plane intersecting the projection axis 41 at right angles (i.e., the XY plane) is a perfect circular shape. In the optical sensor system 100 according to this modification 6, the cross section K2 (refer to FIG. 1 ) of the light projection spot 6 formed by the laser beam Op1 projected from the light projection section 4 onto the plane intersecting the projection axis 41 at right angles is a perfect circular shape. Figure 16 ) is an elliptical shape having a major axis 61, which is different from the optical sensor system 100 according to the above exemplary embodiment. Major axis 61 coincides with a direction (i.e., the X-axis direction) that intersects at right angles with each of the arrangement direction A1 in which the non-lens surface area 3, the second lens surface 22, and the first lens surface 21 are arranged one above the other, and the direction of the projection axis 41. The light beam that forms the projection spot 6 having an elliptical shape (having a major axis 61 that coincides with the X-axis direction) and the light beam that forms the projection spot 6 having a perfect circular shape can be shaped using an optical system such as an optical filter.

[0141] The inventors conducted an inspection to verify the intended effect by causing the light projecting unit 4 to project the laser beam Op1 when the lens 1 was used as the light receiving lens 7 to form an elliptical light projection spot 6 (having a major axis 61 aligned with the X-axis direction).

[0142] Figure 16 1 is a conceptual diagram illustrating a cross section K1 of a light projection spot 6 formed by the optical sensor system 100 according to the exemplary embodiment described above, a cross section K2 of a light projection spot 6 formed by the optical sensor system 100 according to this modification 6, and a cross section K3 of a light projection spot 6 as a comparative example.

[0143] Figure 16 For example, the cross section K1 of the light projection spot 6 formed at a predetermined distance from the light projection unit 4 may have a one-to-one size ratio with respect to the X-axis and the Y-axis, respectively.

[0144] Figure 16 The cross section K2 shown is a cross section of the light projection spot 6 formed by the optical sensor system 100 according to this sixth modification, and has an elliptical shape having a major axis 61 aligned with the X-axis direction. For example, the cross section K2 of the light projection spot 6 formed at a predetermined distance from the light projection portion 4 may have a size ratio of 5 to 1 with respect to the X-axis and the Y-axis, respectively.

[0145] Figure 16 The cross section K3 shown is an ellipse having a major axis 62 aligned with the Y axis. For example, the cross section K3 of the light spot 6 formed at a predetermined distance from the light projecting unit 4 may have a size ratio of 1 to 5 with respect to the X and Y axes, respectively.

[0146] For example, the inventors of the present application conducted a simulation by projecting a laser beam Op1 perpendicularly to a surface (plane) of a workpiece provided for inspection purposes, forming projection spots 6 having cross sections K1 to K3 , respectively. Figure 17 Result of simulation of the amount of reflected light Op2 received at the photosensor 5 after being reflected from the surface of the workpiece is shown in FIG.

[0147] exist Figure 17 In the figure, the horizontal axis represents the detection distance [mm] measured from the light projecting unit 4 to the workpiece surface, and the vertical axis represents the amount of light received at the photosensitive element 5 relative to the detection distance [arbitrary unit (au)]. Note that Figure 17 is a semi-logarithmic plot, where the axes are on a logarithmic scale. Figure 17 Characteristics of the amount of received light with respect to the detection distance (abscissa) falling within the range of 100 mm to 400 mm are shown.

[0148] Figure 17 The perfect circle (1.1) shown in the upper right column of corresponds to the projection spot 6 having the cross section K1. Figure 17 The ellipse (5.1) shown in the upper right column of corresponds to the projection spot 6 with the cross section K2. Figure 17 The ellipse (1.5) shown in the upper right column of corresponds to the projection spot 6 having a cross section K3.

[0149] from Figure 17 It can be seen that at the distance scale falling within the local range from 100 mm to 400 mm, the cross section K1 corresponding to the perfect circle (1.1) and the cross section K2 corresponding to the ellipse (5.1) produce better results than the cross section K3 corresponding to the ellipse (1.5).

[0150] As can be seen, the configuration of this variation 6 makes it easier for the second lens surface 22 of the lens 1 to converge the reflected light Op2 corresponding to the elliptical projection spot 6 having the major axis 61. Consequently, the amount of light received at the photosensitive element 5 can be increased. In particular, forming the projection spot 6 with a cross-sectional shape similar to that of the crescent-shaped second lens surface 22 elongated in the X-axis direction allows the optical sensor system 100 to achieve a good amount of light received near a near point of 200 mm.

[0151] (Variant 7)

[0152] Next, we will refer to Figure 18 A and Figure 18 B describes in detail the lens 1 according to this modification (Modification 7). In the following description, any constituent element of the lens 1 according to this Modification 7 having substantially the same function as its counterpart in the lens 1 according to the above exemplary embodiment will be denoted by the same reference numeral as the counterpart, and its description will be appropriately omitted herein. Note that, Figure 18 A and Figure 2 is a front view of a schematic version of the lens 1 according to Modification 7 (when viewed from the Z-axis positive side). Figure 18 B is along Figure 18 A is a cross-sectional view taken along plane III-III.

[0153] The lens 1 according to this modification 7 is configured as a biconvex lens, which is different from the lens 1 according to the above-described exemplary embodiment.

[0154] According to the embodiment of the variation 7 Figure 18 A and Figure 18 The lens 1 shown in B is configured as a biconvex lens and therefore has a third lens surface 21X (reference Figure 18B), the third lens surface 21X has a curvature on the light exit surface of the lens 1 (i.e., on the negative side of the Z axis). That is, the third lens surface 21X is a lens surface opposite to the first lens surface 21. Note that the curvatures of the third lens surface 21X and the first lens surface 21 may be equal to or different from each other, whichever is appropriate. Figure 18 In the example shown in B, the curvatures of the third lens surface 21X and the first lens surface 21 are different from each other.

[0155] The lens 1 according to this seventh variation allows the curvature provided by the first lens surface 21 to be partially distributed to the second lens surface, thereby allowing the curvature of the first lens surface 21 to be set to a smaller value than in a plano-convex lens such as the lens 1 according to the above exemplary embodiment. Consequently, this allows for improved AR efficiency when the surface of the lens 1 is coated with an anti-reflection coating such as an AR coating.

[0156] (Variant 8)

[0157] Next, we will refer to Figures 19 to 22 The lens 1 according to this modification (Modification 8) will be described in detail. In the following description, any constituent element of the lens 1 according to this Modification 8 having substantially the same function as its counterpart in the lens 1 according to the above exemplary embodiment will be denoted by the same reference numeral as the counterpart, and its description will be omitted herein as appropriate. Note that, Figure 19 as well as Figure 1 is a perspective view illustrating the appearance of a schematic version of the lens 1 according to Modification 8 (when viewed from the front of the lens 1 ).

[0158] Figure 20 A is a graph showing a lens 1 according to an exemplary embodiment (ie, Figure 1 1) is a characteristic diagram of the light intensity distribution of light passing through the lens 1 in the photosensitive plane (represented by the square frame G1) of the photosensitive element 5 and its surroundings. Figure 20 B is a characteristic diagram showing the light intensity distribution of light having passed through the lens 1 according to this modification (ie, modification 8) on and around the photosensitive plane (indicated by the square frame G1) of the photosensitive element 5. Note that Figure 20 A and Figure 20 B shows the light intensity distribution in gray scale.

[0159] Figure 21 Shown are distance measurement characteristics (simulation results) obtained when the lens 1 according to the exemplary embodiment and the lens 1 according to this modification (Modification 8) are used. Figure 21 as well as Figure 7 It is a double logarithmic curve graph, where the horizontal axis represents the detection distance and the vertical axis represents the amount of light received. Figure 21, a curve Q1 represents a distance measurement characteristic Q1 obtained when the lens 1 according to the exemplary embodiment is used. Figure 7 The distance measurement characteristic Q1 shown is the same. On the other hand, Figure 21 The illustrated curve Q3 represents distance measurement characteristics obtained when the lens 1 according to this Modification 8 is used.

[0160] Figure 22 The diagram shows a plano-convex cylindrical lens 1B having an aspherical surface S1 (cylindrical lens surface 220). The lens 1 according to this modification (Modification 8) has a second lens surface 22 having a Figure 22 A portion of the aspherical surface S1 (i.e., cylindrical lens surface 220) of the plano-convex cylindrical lens 1B is shown. Figure 22 , a region of the cylindrical lens surface 220 of the cylindrical lens 1B serving as the second lens surface 22 is indicated for reference.

[0161] In the lens 1 according to this modification 8, as Figure 19 and Figure 22 As shown, if the origin of the XYZ coordinate system is set so that the generatrix direction consistent with the generatrix D1 relative to the cylindrical lens surface 220 intersects the Z axis (reference Figure 22 ), the generatrix direction consistent with the generatrix D1 intersects the Y axis, and the generatrix D1 appears on the surface of the second lens surface 22, which is different from the lens 1 according to the above exemplary embodiment.

[0162] Specifically, the lens 1 according to this modification 8 includes a cylindrical lens surface 220. The generatrix direction that coincides with the generatrix D1 relative to the cylindrical lens surface 220 is (substantially) parallel to the arrangement direction A1 (i.e., the Y-axis direction) in which the non-lens surface area 3, the second lens surface 22, and the first lens surface 21 are arranged one above the other when viewed along the optical axis C1 passing through the vertex P1. In addition, the second lens surface 22 of the lens 1 according to modification 8 is configured to include the generatrix D1 relative to the cylindrical lens surface 220 (i.e., Figure 22 A portion of the generatrix D1 relative to the cylindrical lens 1B).

[0163] like Figure 20 As shown in FIG. 1A , in the lens 1 according to the exemplary embodiment, the intensity distribution of light transmitted through the second lens surface 22 (i.e., the cylindrical lens surface 220 ) itself appears as a horizontally long intensity distribution extending in the X-axis direction relative to the photosensitive plane. Note that Figure 20 In A, reference numeral “M1” denotes a spot image obtained from the first lens surface 21 of the lens 1 according to the exemplary embodiment, and reference numeral “M2” denotes a spot image obtained from the second lens surface 22 of the lens 1 according to the exemplary embodiment.

[0164] On the other hand, Figure 20 As shown in FIG. 1B , in the lens 1 according to this modification 8, the intensity distribution of light passing through the second lens surface 22 (i.e., the cylindrical lens surface 220) itself appears as a vertically long intensity distribution extending in the Y-axis direction relative to the photosensitive plane. Note that Figure 20 In B, reference numeral “ M3 ” denotes a spot image obtained from the first lens surface 21 of the lens 1 according to Modification 8, and reference numeral “ M4 ” denotes a spot image obtained from the second lens surface 22 of the lens 1 according to Modification 8.

[0165] In the lens 1 according to the exemplary embodiment, the generatrix D1 relative to the cylindrical lens surface 220 is parallel to the X-axis direction. Therefore, as the detection distance changes, the light intensity distribution, which manifests itself as a long intensity distribution in the horizontal direction, can move up and down relative to the photosensitive plane (i.e., to the positive side or negative side of the Y-axis).

[0166] On the other hand, in the lens 1 according to this modification 8, the generatrix D1 relative to the cylindrical lens surface 220 is parallel to the arrangement direction A1 (Y-axis direction) and not parallel to the X-axis direction. Therefore, the light intensity distribution that itself exhibits a vertically long intensity distribution continues to remain on the photosensitive plane regardless of changes in the detection distance. That is, in the lens 1 according to modification 8, the light intensity distribution changes to a lesser extent according to the distance. In addition, in the lens 1 according to modification 8, the amount of received light is as follows Figure 21 The distance measurement characteristic Q3 shown varies to a lesser extent than the distance measurement characteristic Q1 and exhibits a wider waveform than the distance measurement characteristic Q1. This allows the lens 1 according to Modification 8 to be designed to have a constant distance measurement characteristic regardless of the detection distance.

[0167] (Summary)

[0168] The above-described exemplary embodiments and modifications thereof are specific implementations of the following aspects of the present disclosure.

[0169] According to the first aspect, the lens (1) includes: a lens surface region (2) having a lens surface (20) that converges incident light (such as reflected light Op2); and a non-lens surface region (3) in which the lens surface (20) is not present. The lens surface (20) includes: a first lens surface (21) that is a convex lens surface and is configured as a convex curved surface (CV1) having a vertex (P1); and a second lens surface (22) that is an aspherical surface and has a curvature different from that of the first lens surface (21). The axis (222) of the principal ray defined relative to the second lens surface (22) is non-coaxial with the axis (211) of the principal ray defined relative to the first lens surface (21).

[0170] This aspect achieves an advantage of helping to more accurately focus incident light even if the incident light has traveled a distance falling within a wider range before being incident on the lens (1).

[0171] In a lens (1) according to a second aspect that can be implemented in combination with the first aspect, when viewed along an optical axis (C1) passing through a vertex (P1), a second lens surface (22) is interposed between the first lens surface (21) and the non-lens surface area (3) in a manner extending along at least a portion of a boundary (B1) between the lens surface area (2) and the non-lens surface area (3).

[0172] This aspect allows for even more precise focusing of incident light even if the incident light has travelled a distance falling within a wider range before impinging on the lens (1).

[0173] In the lens (1) according to the third aspect which can be implemented in combination with the first or second aspect, the second lens surface (22) includes a cylindrical lens surface (220). A generatrix direction that coincides with a generatrix (D1) relative to the cylindrical lens surface (220) intersects with an arrangement direction (A1) in which the non-lens surface region (3), the second lens surface (22), and the first lens surface (21) are arranged one above the other when viewed along an optical axis (C1) passing through a vertex (P1).

[0174] This aspect makes it easier to realize the second lens surface (22) that allows incident light to be concentrated more accurately.

[0175] In the lens (1) according to the fourth aspect which can be implemented in combination with the third aspect, the second lens surface (22) is configured not to include a generating line (D1) relative to the cylindrical lens surface (220).

[0176] This aspect makes it easier to realize the second lens surface (22) that allows incident light to be more accurately converged compared to the case where the second lens surface (22) includes the generating line (D1).

[0177] In the lens (1) according to the fifth aspect which can be implemented in combination with the third or fourth aspect, the second lens surface (22) includes a plurality of cylindrical lens surfaces (220), and the plurality of cylindrical lens surfaces (220) have focal points at mutually different positions in the configuration direction (A1).

[0178] This aspect allows incident light to be focused more precisely even if the incident light has traveled a distance that falls within a wider range.

[0179] In the lens (1) according to the sixth aspect which can be implemented in combination with any one of the first to fifth aspects, the second lens surface (22) is arranged adjacent to the non-lens surface area (3).

[0180] This aspect allows for a more precise focusing of the incident light.

[0181] In the lens (1) according to the seventh aspect which can be implemented in combination with any one of the first to sixth aspects, the non-lens surface area (3) has a notch structure (V1) wherein a boundary (B1) between the lens surface area (2) and the non-lens surface area (3) is recessed inwardly relative to the lens surface area (2) when viewed along an optical axis (C1) passing through the vertex (P1).

[0182] This aspect helps increase the amount of received reflected light (OP2) by placing the light projecting portion (4) and other components in the non-lens surface area (3).

[0183] In the lens (1) according to the eighth aspect which can be implemented in combination with any one of the first to seventh aspects, when observed along the optical axis (C1) passing through the vertex (P1), the second lens surface (22) is formed in the shape of a crescent extending along at least a portion of the boundary (B1) between the lens surface area (2) and the non-lens surface area (3).

[0184] This aspect makes it easier to reduce the area of ​​the lens surface (20) occupied by the second lens surface (22).

[0185] In the lens (1) according to the ninth aspect which can be implemented in combination with any one of the first to eighth aspects, at least one of the first lens surface (21) or the second lens surface (22) has a Fresnel structure (X1).

[0186] This aspect not only helps to reduce the thickness of the lens (1) more effectively, but also helps to reduce the material cost of the lens (1).

[0187] In the lens (1) according to the tenth aspect which can be implemented in combination with any one of the first to ninth aspects, the second lens surface (22) includes an annular lens surface (221). The second lens surface (22) is configured not to include a vertex (P2) of the annular lens surface (221).

[0188] This aspect makes it easier to realize the second lens surface (22) that allows incident light to be more accurately converged, compared to a case where the second lens surface (22) includes the vertex (P2).

[0189] In the lens (1) according to the eleventh aspect that can be implemented in combination with the first or second aspect, the second lens surface (22) includes a cylindrical lens surface (220). A generatrix direction that coincides with a generatrix (D1) relative to the cylindrical lens surface (220) is (substantially) parallel to an arrangement direction (A1) in which the non-lens surface region (3), the second lens surface (22), and the first lens surface (21) are arranged one above the other when viewed along an optical axis (C1) passing through the vertex (P1). The second lens surface (22) is configured to include the generatrix (D1) relative to the cylindrical lens surface (220).

[0190] According to this aspect, a portion of the light transmitted through the second lens surface (22) continues to reach the image point (J1) regardless of the detection distance, thereby achieving a design that makes the distance measurement characteristics almost constant regardless of the detection distance.

[0191] In the lens (1) according to the twelfth aspect which can be implemented in combination with any one of the first to eleventh aspects, the lens (1) is configured as a biconvex lens and further has a third lens surface (21X) whose light exit surface has a curvature.

[0192] This aspect allows the first lens surface (21) to be designed to have a smaller curvature, thereby allowing the efficiency of the anti-reflection film provided as a coating covering the surface of the lens (1) to be improved.

[0193] The optical sensor system (100) according to the thirteenth aspect includes a light projecting unit (4), a lens (1) according to any one of the first to twelfth aspects, and a photosensitive element (5). The light projecting unit (4) projects a laser beam (Op1) toward a measurement object (Ob1). The lens (1) converges reflected light (Op2) from the measurement object (Ob1). The photosensitive element (5) receives the light converged by the lens (1) and converts the light into an electrical signal. The photosensitive element (5) is configured so that a light receiving axis (51) of the photosensitive element (5) coincides with an optical axis (C1) passing through the vertex (P1). The light projecting axis 41 and the light receiving axis 51 of the light projecting unit 4 are parallel to each other with respect to the optical axis C1.

[0194] This aspect achieves the advantage of providing an optical sensor system (100) including a lens (1) that helps to more accurately focus incident light even if the incident light has traveled a distance falling within a wider range before being incident on the lens (1).

[0195] In the optical sensor system (100) according to the fourteenth aspect which can be implemented in combination with the thirteenth aspect, the first lens surface (21) is a long-distance lens surface with respect to the distance to the measurement object (Ob1). The second lens surface (22) is a short-distance lens surface with respect to the distance to the measurement object (Ob1).

[0196] This aspect allows incident light to be more accurately focused on the first lens surface (21) when the distance to the object to be measured (Ob1) is "far away." This aspect also allows incident light to be more accurately focused on the second lens surface (22) when the distance to the object to be measured (Ob1) is "close." Therefore, the amount of light received by the photosensor (5) can be increased.

[0197] In the optical sensor system (100) according to the fifteenth aspect which can be implemented in combination with the thirteenth or fourteenth aspect, the light projecting portion (4) is placed inside the non-lens surface area (3).

[0198] According to this aspect, the light projection axis (41) and the light receiving axis (51) are located closer to each other, thereby allowing the lens (1) to focus the incident light even more accurately. Therefore, the amount of light received at the photosensitive element (5) can be increased.

[0199] In the optical sensor system (100) according to the sixteenth aspect, which can be implemented in combination with any one of the thirteenth to fifteenth aspects, the second lens surface (22) includes a cylindrical lens surface (220) or an annular lens surface (221). A vertex (P2) of the annular lens surface (221) with respect to a generatrix (D1) of the cylindrical lens surface (220) is located between the light projection axis (41) and the light receiving axis (51).

[0200] According to this aspect, in other words, the second lens surface (22) is configured to be offset relative to the vertex (P1) of the first lens surface (21), thereby allowing the lens (1) to focus incident light even more accurately. As a result, the amount of light received at the photosensitive element (5) can be increased.

[0201] In the optical sensor system (100) according to the seventeenth aspect which can be implemented in combination with any one of the thirteenth to sixteenth aspects, the light projection axis (41) and the light receiving axis (51) are configured to be non-coaxial with each other.

[0202] This aspect allows the lens (1) to focus incident light more accurately than when the light-projecting axis (41) and the light-receiving axis (51) are arranged coaxially with each other, thereby increasing the amount of light received at the photosensitive element (5).

[0203] In the optical sensor system (100) according to the eighteenth aspect which can be implemented in combination with any one of the thirteenth to seventeenth aspects, a cross section of a light projection spot (6) formed by the laser beam (Op1) projected from the light projection section (4) on a plane intersecting the light projection axis (41) at right angles has an elliptical shape having a major axis (61). The major axis (61) coincides with a direction perpendicular to each of an arrangement direction (A1) in which the non-lens surface area (3), the second lens surface (22), and the first lens surface (21) are arranged one above the other, and a direction in which the light projection axis (41) extends.

[0204] This aspect makes it easier to converge the reflected light (Op2) corresponding to the elliptical projection spot (6) having the major axis (61) onto the second lens surface (22) of the lens (1). Therefore, the amount of light received at the photosensitive element (5) can be increased.

[0205] Note that the components according to the second to twelfth aspects are not essential components of the lens (1) and can be omitted as appropriate. It should also be noted that the components according to the fourteenth to eighteenth aspects are not essential components of the optical sensor system (100) and can be omitted as appropriate.

[0206] Reference Signs List

[0207] 1 lens

[0208] 2 Lens surface area

[0209] 20 Lens surface

[0210] 21 First lens surface

[0211] 211 Axis of the principal ray

[0212] 22 Second lens surface

[0213] 220 cylindrical lens surface

[0214] 221 Annular lens surface

[0215] 222 Axis of the principal ray

[0216] 3 Non-lens surface area

[0217] 4 light projection part

[0218] 41 Light projection axis

[0219] 5 Photosensitive element

[0220] 51 Light receiving axis

[0221] 6 Light spot

[0222] 61 Spindle

[0223] 100 Optical Sensor System

[0224] A1 Configuration Direction

[0225] B1 Boundary

[0226] C1 optical axis

[0227] Cv1 convex surface

[0228] D1 (cylindrical lens surface) busbar

[0229] Ob1 Measurement object

[0230] Op1 laser beam

[0231] Op2 reflected light

[0232] P1 vertex

[0233] P2 (vertex of the annular lens surface)

[0234] V1 notch structure

[0235] X1 Fresnel structure

Claims

1. A lens comprising: a lens surface region having a lens surface configured to focus incident light; a non-lens surface region, where the lens surface is not present, The lens surface comprises: a first lens surface, which is a convex lens surface, wherein the first lens surface is configured as a convex curved surface having a vertex; as well as a second lens surface that is aspherical, the second lens surface having a different curvature from the first lens surface, An axis of a chief ray defined with respect to the second lens surface is non-coaxial with an axis of a chief ray defined with respect to the first lens surface.

2. The lens according to claim 1, wherein When viewed along an optical axis passing through the vertex, the second lens surface is interposed between the first lens surface and the non-lens surface area so as to extend along at least a portion of a boundary between the lens surface area and the non-lens surface area.

3. The lens according to claim 1 or 2, wherein: The second lens surface includes a cylindrical lens surface, and A generatrix direction coinciding with a generatrix with respect to the cylindrical lens surface intersects an arrangement direction in which the non-lens surface area, the second lens surface, and the first lens surface are arranged one above the other when viewed along an optical axis passing through the vertex.

4. The lens according to claim 3, wherein: The second lens surface is configured not to include the generating line relative to the cylindrical lens surface.

5. The lens according to claim 3 or 4, wherein: The second lens surface includes a plurality of cylindrical lens surfaces, and The plurality of cylindrical lens surfaces have focal points at mutually different positions in the arrangement direction.

6. The lens according to any one of claims 1 to 5, wherein: The second lens surface is configured to be adjacent to the non-lens surface area.

7. The lens according to any one of claims 1 to 6, wherein: The non-lens surface region has a notch structure in which a boundary between the lens surface region and the non-lens surface region is recessed inwardly relative to the lens surface region when viewed along an optical axis passing through the vertex.

8. The lens according to any one of claims 1 to 7, wherein: The second lens surface has a crescent shape extending along at least a portion of a boundary between the lens surface region and the non-lens surface region when viewed along an optical axis passing through the vertex.

9. The lens according to any one of claims 1 to 8, wherein: At least one of the first lens surface and the second lens surface has a Fresnel structure.

10. The lens according to any one of claims 1 to 9, wherein: The second lens surface comprises an annular lens surface, and The second lens surface is configured not to include a vertex of the annular lens surface.

11. The lens according to claim 1 or 2, wherein: the second lens surface comprises a cylindrical lens surface, A generatrix direction coinciding with a generatrix with respect to the cylindrical lens surface is parallel to an arrangement direction in which the non-lens surface area, the second lens surface, and the first lens surface are arranged one above the other when viewed along an optical axis passing through the vertex, and The second lens surface is configured to include the generating line relative to the cylindrical lens surface.

12. An optical sensor system comprising: a light projecting unit configured to project a laser beam toward an object to be measured; The lens according to any one of claims 1 to 11, wherein the lens is configured to converge reflected light from the object to be measured; as well as a photosensitive element configured to receive the light focused by the lens and convert the light into an electrical signal, The photosensitive element is configured so that the light receiving axis of the photosensitive element coincides with the optical axis passing through the vertex, and The light projection axis and the light receiving axis of the light projection portion are parallel to each other with respect to the optical axis.

13. The optical sensor system according to claim 12, wherein: The first lens surface is a distance lens surface with respect to the distance to the measurement object, and The second lens surface is a close-range lens surface with respect to a distance to a measurement object.

14. The optical sensor system according to claim 12 or 13, wherein: The light projecting portion is placed inside the non-lens surface area.

15. The optical sensor system according to any one of claims 12 to 14, wherein: The second lens surface includes a cylindrical lens surface or a toroidal lens surface, and The generating line relative to the cylindrical lens surface or the vertex of the annular lens surface is between the light projection axis and the light receiving axis.

16. The optical sensor system according to any one of claims 12 to 15, wherein: The light projection axis and the light receiving axis are configured to be non-coaxial with each other.

17. The lens according to any one of claims 12 to 16, wherein: The cross section of the light spot formed by the laser beam projected by the light projecting portion on a plane intersecting the light projection axis at right angles is in the shape of an ellipse having a major axis, and The major axis coincides with a direction perpendicular to each of an arrangement direction in which the non-lens surface area, the second lens surface, and the first lens surface are arranged one above the other, and a direction in which the light projection axis extends.

Images