Lens support structure and optical distance measuring sensor

Abstract

To provide a lens support structure in which application balance of adhesive is stabilized and which suppresses deviation of an optical axis even against vibration or impact from the outside.SOLUTION: A lens support structure comprises a lens, a frame body holding the lens, and a base member supporting the frame body. The frame body has a pair of arm units extending in a direction not in parallel to an optical axis of the lens to be held and a projection unit provided in such a manner that it projects from a distal end of the arm unit to a side of the base member. The base member includes a flat portion and a raised portion that is raised from the flat portion to a side of the projection unit and comprises in an upper surface portion thereof, a recess for storing adhesive. The frame body is supported by the base member by inserting a distal end portion of the projection unit of the frame body into the recess of the raised portion and being surrounded by the adhesive.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a lens support structure and an optical distance measuring sensor. [Background technology]

[0002] A lens is incorporated into an optical distance measuring sensor etc. with its position adjusted three-dimensionally. A lens holder that holds the lens is often fixed to a base frame via an adhesive (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-144158 Summary of the Invention [Problem to be solved by the invention]

[0004] If the adhesive hardens while dripping in the direction of gravity or spreading in the direction of the adhesive surface, the adhesive may become unevenly applied to the lens holder. If the adhesive hardens in this way with an uneven balance, it will cause the lens optical axis to shift when it expands or contracts due to temperature changes in the lens's environment. If such a lens is incorporated into an optical distance measuring sensor, for example, this can cause output errors.

[0005] The present invention has been made to solve these problems, and provides a lens support structure that stabilizes the balance of adhesive application and suppresses optical axis deviation even in the event of external vibration or impact, as well as an optical distance measuring sensor that employs the same. [Means for solving the problem]

[0006] A first aspect of the present invention provides a lens support structure comprising a lens, a frame for holding the lens, and a base member for supporting the frame. The frame has a pair of arms extending in a direction not parallel to the optical axis of the lens being held and a protrusion extending from the tip of the arm toward the base member. The base member has a flat portion and a raised portion that rises from the flat portion toward the protrusion and has a recess for storing adhesive on its upper surface. The frame is supported by the base member by inserting the tip of the protrusion of the frame into the recess of the raised portion and being surrounded by the adhesive. With this lens support structure, the adhesive is stored in the recess of the raised portion, preventing it from dripping or spreading during bonding, and allowing for balanced support of the frame for holding the lens. Furthermore, because the recess is located on the upper surface of the raised portion that rises from the base member, the length of the protrusion can be reduced. Therefore, even if the base member is subjected to vibration or impact after being fixed, resonance of the frame can be suppressed, and the optical axis of the lens can be stably maintained.

[0007] In the above-described lens support structure, the upper surface may be positioned above the lower end of the lens held by the frame. This arrangement is expected to not only effectively suppress vibration of the frame, but also to improve the workability of workers pouring adhesive into the recesses and irradiating the adhesive with ultraviolet light.

[0008] Furthermore, in the above-described lens support structure, a groove may be provided in a portion of the wall forming the recess to allow adhesive that overflows from the recess to flow out. By providing such a guide groove, even if a worker accidentally pours a large amount of adhesive into the recess, the excess adhesive can be directed in a specific direction, thereby preventing adverse effects on the support of the lens.

[0009] In the above-described lens support structure, the length of the protrusion parallel to the optical axis direction of the lens may be longer than the length of protrusion from the arm toward the base member. If the arm is provided to extend, for example, in a direction perpendicular to the optical axis of the lens, vibrations and impacts are likely to cause the lens to tilt, but if the protrusion is formed relatively long in the optical axis direction of the lens, the lens will be more resistant to tilt.

[0010] Furthermore, in the above-described lens support structure, a through hole may be provided at the boundary between the arm portion and the protrusion. In particular, when the arm portion or protrusion is formed long in the optical axis direction, the UV light from the UV irradiator that cures the adhesive is largely blocked by these components. However, by providing such a through hole, more UV light can reach the adhesive.

[0011] In the above-described lens support structure, the adhesive may include at least an ultraviolet-curable adhesive, and the surface of the recess may be surface-treated so that the ultraviolet reflectance of the surface is greater than the ultraviolet reflectance of the surface of the flat portion. In a lens support structure, the surfaces of each component are usually subjected to a light-shielding treatment to prevent reflection of stray light, but it is preferable that the surface of the recess be surface-treated in this manner, as reflecting UV light from a UV irradiator contributes to curing of the adhesive.

[0012] An optical distance measuring sensor according to a second aspect of the present invention employs the lens support structure described above as a structure for supporting at least one of a light-emitting lens disposed between the light-emitting element and the light-projecting window, and a light-receiving lens disposed between the light-receiving window and the light-receiving sensor. Optical distance measuring sensors are often used in environments where the ambient temperature changes drastically or where they are frequently subjected to large vibrations and shocks. However, even when used in such environments, an optical distance measuring sensor employing the lens support structure described above can stably maintain the lens optical axis and output accurate detection results. [Effects of the Invention]

[0013] The present invention makes it possible to provide a lens support structure that stabilizes the balance of adhesive application and suppresses deviation of the optical axis even when subjected to external vibrations or impacts, and an optical distance measuring sensor that employs the same. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a perspective view showing a state in which the distance measuring sensor according to the present embodiment is used. [Figure 2] FIG. 2 is a perspective view showing the arrangement of main components fixed to a base frame. [Figure 3] FIG. [Figure 4] FIG. 2 is a perspective view of a light-receiving lens holder that holds a light-receiving lens. [Figure 5] 10 is a cross-sectional view showing a state of a light-receiving lens holder supported by a base frame. FIG. [Figure 6] FIG. 2 is a perspective view of a projection lens holder that holds a projection lens. DETAILED DESCRIPTION OF THE INVENTION

[0015]

[0023] An embodiment of the present invention will be described with reference to the accompanying drawings. In each drawing, components with the same reference numerals have the same or similar configurations. In addition, when multiple structures with the same or similar configurations exist in each drawing, in order to avoid complication, some components may be referenced with the same reference numerals and others may not be referenced with the same reference numerals.

[0016] FIG. 1 is a perspective view showing a usage state of a distance measuring sensor 100 according to this embodiment. The distance measuring sensor 100 according to this embodiment is an example of an optical distance measuring sensor, and is installed and used, for example, on a factory production line. The distance measuring sensor 100 projects detection light L1 emitted by a light-emitting element through a light-emitting window 113 toward a workpiece W, which is the object to be detected. Then, detection light L2 reflected by the workpiece W and returned is received by a light-receiving sensor through a light-receiving window 114, and the distance to the workpiece W is measured based on the light-receiving position.

[0017] In addition to the light-emitting element and light-receiving sensor, the housing 111 also contains a light-projecting lens for projecting detection light L1 onto the workpiece W, a light-receiving lens for guiding detection light L2 to the light-receiving sensor, and a control board equipped with a processing circuit including a CPU. The detection signal photoelectrically converted by the light-receiving sensor is transmitted to the amplifier unit via cable 112. The amplifier unit converts the received detection signal into a numerical value and displays it on a display unit or outputs it to an external device such as a PLC or PC. Note that the distance measuring sensor 100 may also incorporate the amplifier unit function. In this case, the housing 111 includes a display unit for displaying numerical values ​​and a communication unit for communicating with external devices. The x-, y-, and z-axes are defined as shown. In subsequent drawings, the same coordinate axes as in FIG. 1 are also included to indicate the orientation of the structures depicted in each drawing.

[0018] 2 is a perspective view showing the arrangement of the main components fixed to base frame 120. Base frame 120 is a base member that supports at least light-receiving lens holder 140 that holds light-receiving lens 130, light-projecting lens holder 160 that holds light-projecting lens 150, reflecting mirror 170, light-receiving sensor 180, and light-emitting element 190. Note that depending on the configuration of the distance measuring sensor, it may not include a reflecting mirror. Base frame 120 is formed, for example, from aluminum die-casting.

[0019] 2, the light emitting element 190 fixed to the fitting frame 128 is, for example, a laser diode and emits detection light L1. The detection light L1 emitted from the light emitting element 190 is adjusted by the light projecting lens 150 to be parallel light or a defined spot light, and is projected toward the workpiece W after passing through the above-mentioned light projecting window 113. The structure of the light projecting lens holder 160 that holds the light projecting lens 150 and the fixing of the light projecting lens holder 160 to the base frame 120 will be described in detail later.

[0020] When the detection light L1 is reflected by the workpiece W, it returns to the distance measuring sensor 100 as detection light L2 along an optical path corresponding to the distance to the workpiece W. After passing through the above-mentioned light receiving window 114, the detection light L2 is focused by the light receiving lens 130, reflected by the reflecting mirror 170, and reaches the light receiving sensor 180. The light receiving sensor 180 is, for example, a CMOS sensor having multiple pixels, and outputs an electrical signal corresponding to the pixel at which the detection light L2 reaches. In this embodiment, the reflecting mirror 170 is adhesively fixed to the housing frame 129 of the base frame 120, and the light receiving sensor 180 is supported on the base frame 120 via a sensor holder 181.

[0021] 3 is a perspective view of base frame 120. Base frame 120 has an overall structure in which a plurality of structures, each with its own function, are erected on plate-like bottom surface 121. In this embodiment, base frame 120 is integrally formed as a whole by aluminum die-casting, but the material may be resin or other metal, or some of the structures may be formed separately and fixed.

[0022] Bottom surface 121 is mainly divided into light-receiving side bottom surface 121a on which structures supporting components related to light reception are erected, and light-emitting side bottom surface 121b on which structures supporting components related to light projection are erected. Light-receiving side bottom surface 121a and light-emitting side bottom surface 121b are formed as approximately flat portions, but may have light-shielding lines to prevent stray light or may have hollowed-out portions.

[0023] In addition to the above-mentioned housing frame 129, the light-receiving side bottom surface 121a has two raised portions 122 for supporting the light-receiving lens holder 140. Each raised portion 122 is substantially rectangular prism-shaped and protrudes upward (in the negative y-axis direction in the figure) from the light-receiving side bottom surface 121a (parallel to the xz plane in the figure). Each upper surface portion 122a is provided with a recessed portion 123 that is a depression for storing adhesive. In addition, a guide groove 124 is provided in a part of the wall portion that forms the recessed portion 123 in the upper surface portion 122a to direct overflowing adhesive in a specific direction if an operator accidentally pours a large amount of adhesive into the recessed portion 123.

[0024] In this embodiment, recesses 123 are provided by being dug in a bathtub shape in upper surface 122a of each raised portion 122. Furthermore, guide grooves 124 are provided in a direction along the optical axis of light-receiving lens 130. When the amount of adhesive flowing in exceeds the capacity of recesses 123, the overflowing adhesive flows through guide grooves 124 to light-receiving-side bottom surface 121a.

[0025] In addition to the fitting frame 128 described above, the light-emitter side bottom surface 121b has two raised portions 125 for supporting the light-emitter lens holder 160. Each raised portion 125 is substantially rectangular prism-shaped and protrudes upward (in the negative y-axis direction in the figure) from the light-emitter side bottom surface 121b (parallel to the xz plane in the figure). Each upper surface portion 125a is provided with a recessed portion 126 that is a depression for storing adhesive. In addition, a guide groove 127 is provided in a part of the wall portion that forms the recessed portion 126 in the upper surface portion 125a to direct overflowing adhesive in a specific direction if an operator accidentally pours a large amount of adhesive into the recessed portion 126.

[0026] In this embodiment, recesses 126 are provided by being dug in a bathtub shape in upper surface 125a of each raised portion 125. Furthermore, guide groove 127 is provided in a direction along the optical axis of projector lens 150. When the amount of adhesive flowing in exceeds the capacity of recess 126, the overflowing adhesive flows through guide groove 127 to light-projection-side bottom surface 121b. Note that the direction in which the guide groove is provided is not limited to the direction along the optical axis, and may be any direction that prevents the overflowing adhesive from contacting optical components such as light-receiving lens holder 140.

[0027] 4 is a perspective view of the light receiving lens holder 140 that holds the light receiving lens 130. The light receiving lens holder 140 is a frame that surrounds and holds the peripheral portion of the light receiving lens 130, and is molded from, for example, resin. The light receiving lens holder 140 mainly has a frame portion 141, arms 142, and protrusions 143. The frame portion 141 functions to surround and hold the peripheral portion of the light receiving lens 130, and the light receiving lens 130 is fixed using an adhesive after being positioned on the frame portion 141. The frame portion 141 does not have to surround the entire periphery of the light receiving lens 130; in this embodiment, a portion corresponding to the lower end portion of the light receiving lens 130 is cut out.

[0028] Arms 142 are a pair of beam-like portions that extend from frame 141 in a direction perpendicular to the optical axis of light receiving lens 130 when frame 141 holds it, and in a direction parallel to the xz plane in this embodiment. Protrusions 143 are hook-like portions that protrude from the tip of each arm 142 in a direction perpendicular to the extension direction of arm 142 (in this embodiment, the y-axis direction, which is the side of the base member).

[0029] 5 is a cross-sectional view showing the state of light-receiving lens holder 140 supported by base frame 120, specifically a cross-sectional view taken along plane C shown in FIG. 2. As described above, a pair of left and right raised portions 122 are provided to protrude from light-receiving-side bottom surface 121a, and recesses 123 are dug in the top surface portions 122a of each. In this embodiment, UV-curable adhesive 200 is stored in recesses 123, which hardens when irradiated with UV light (ultraviolet light) by UV irradiator 210. The figure shows the state in which the stored adhesive 200 has hardened and light-receiving lens holder 140 has been fixed.

[0030] As described above, a pair of arms 142 extend laterally from frame portion 141, and the tips of protrusions 143, each formed so as to be bent, are inserted into recesses 123 and surrounded by adhesive 200. The tips of protrusions 143 are fixed with hardened adhesive 200, thereby supporting light-receiving lens holder 140 on base frame 120. When observing light-receiving lens holder 140 in a state supported on base frame 120, raised portion 122 is provided so as to protrude from light-receiving-side bottom surface 121a toward protrusion 143, and the protrusion can be said to protrude from the tips of arms 142 toward light-receiving-side bottom surface 121a.

[0031] During the process of fixing light-receiving lens holder 140 to base frame 120, light-receiving lens holder 140 is suspended by a jig with the tip of protrusion 143 immersed in uncured adhesive 200. Detection light L2, which is reflected light of detection light L1 emitted for adjustment, is actually received by light-receiving sensor 180, and an operator adjusts the position and orientation of light-receiving lens holder 140 by displacing the jig while observing the output. Once the position and orientation are confirmed, UV light is irradiated from UV irradiator 210, and adhesive 200 is cured. Once adhesive 200 has cured, the jig releases the holder.

[0032] When fixing light-receiving lens holder 140 to base frame 120 through these work steps, first, recess 123 for storing adhesive 200 is provided on the upper surface of raised portion 122, making it easy for the worker to pour in adhesive 200. Furthermore, because adhesive 200 is stored in recess 123, adhesive 200 does not spread in the surface direction or drip in the direction of gravity, and therefore light-receiving lens holder 140, which has been adjusted when adhesive 200 hardens, does not shift. Note that this work of fixing light-receiving lens holder 140 may also be achieved without the intervention of a worker, by, for example, a work robot recognizing the output of light-receiving sensor 180 and automatically displacing the jig.

[0033] The light receiving lens holder 140 fixed to the base frame 120 in this manner has a good application balance of the adhesive 200, i.e., good adhesion symmetry between the two protrusions 143. Good adhesion symmetry prevents the protrusions 143 from being pressed in a biased direction even when the hardened adhesive 200 expands or contracts due to temperature changes in the usage environment of the distance measuring sensor 100, thereby minimizing changes in the optical axis of the light receiving lens 130. Furthermore, the tip of the protrusion 143 inserted into the recess 123 does not come into contact with the recess 123, but only with the adhesive 200. With this structure, even if external vibrations or impacts are applied in the usage environment, the adhesive 200, which has lower rigidity than the base frame 120 and the light receiving lens holder 140, absorbs them, and displacement of the light receiving lens holder 140 can be expected to be suppressed.

[0034] Furthermore, in this embodiment, the distance h2 from the light-receiving-side bottom surface 121a to the top surface 122a is greater than the distance h1 from the light-receiving-side bottom surface 121a to the bottom end of the effective diameter of the light-receiving lens 130. In other words, the top surface 122a is located above the bottom end of the effective diameter of the light-receiving lens 130 held by the light-receiving lens holder 140. If the raised portion 122 is set higher within this range, the protrusion 143 of the light-receiving lens holder 140 can be shortened. If the protrusion 143 can be shortened, bending of the protrusion 143 can be suppressed even when the light-receiving lens is subjected to external vibrations or impacts or when the adhesive 200 expands / contracts, and thus displacement of the optical axis of the light-receiving lens 130 can be suppressed.

[0035] In this embodiment, the entire base frame 120 is anodized except for at least the recess 123. The anodized surface provides light absorption, effectively absorbing stray light of the detection lights L1 and L2. On the other hand, the surface of the recess 123, which stores the UV-curable adhesive 200, is better able to reflect UV light, which contributes to the curing of the adhesive 200. Therefore, the surface of the recess 123 is not anodized. The difference in the treatment between the surface of the recess 123 and the other surfaces of the base frame 120 is not limited to this method. The surface of the recess 123 may be subjected to a mirror finish, such as aluminum deposition, to increase the UV reflectance of the recess 123 relative to the other surfaces, particularly the surface of the light-receiving-side bottom surface 121a.

[0036] In this embodiment, projector lens holder 160 that holds projector lens 150 is also fixed to base frame 120, similar to light-receiving lens holder 140. Figure 6 is a perspective view of projector lens holder 160 that holds projector lens 150.

[0037] Projector lens holder 160 is a frame that surrounds and holds the peripheral portion of projector lens 150, and is molded from, for example, resin. Projector lens holder 160 mainly has a frame portion 161, arms 162, and protrusions 163. Frame portion 161 functions to surround and hold the peripheral portion of projector lens 150, and projector lens 150 is fixed using an adhesive after being positioned on frame portion 161. Frame portion 161 is box-shaped, and may hold a projector lens group consisting of multiple projector lenses.

[0038] The arm portions 162 are a pair of beam-like portions that extend from the frame portion 161 in a direction perpendicular to the optical axis of the projection lens 150 when the frame portion 161 holds the projection lens 150, and in a direction parallel to the xz plane in this embodiment. The protrusions 163 are hook-like portions that protrude from the tip of each arm portion 162 in a direction perpendicular to the extension direction of the arm portions 162 (in this embodiment, the y-axis direction, which is the side of the base member).

[0039] The width w of the arm 162 of the light-receiving lens holder 160 along the optical axis direction is wider than that of the light-receiving lens holder 140. Specifically, the width w is greater than the height h, which is the length of projection of the protrusion 163 from the arm 162. If the arm is provided to extend in a direction perpendicular to the optical axis of the lens, vibrations and impacts are likely to cause the lens to tilt in the plane of the lens; however, if the protrusion 163 is formed relatively long along the optical axis direction of the light-receiving lens 150 in this way, the lens will be more resistant to plane tilt.

[0040] Furthermore, a through-hole 164 is provided at the boundary between the arm portion 162 and the protrusion 163. When the tip of the protrusion 163 is inserted into the adhesive 200 stored in the recess 126 of the raised portion 125, the through-hole 164 functions to pass the irradiated UV light and guide more UV light to the adhesive 200. Therefore, it can be expected that the adhesive 200 will harden faster than if the through-hole 164 were not provided.

[0041] Projector lens holder 160 configured in this manner can also be fixed to base frame 120 in the same manner as the fixing method for light-receiving lens holder 140 described using Fig. 5. In the case of projector lens holder 160, the tip of protrusion 163 is held suspended by a jig while immersed in uncured adhesive 200, and the position and orientation of projector lens holder 160 can be adjusted by an operator displacing the jig while observing the spot light of detection light L1 projected for adjustment.

[0042] The distance measuring sensor 100 according to this embodiment has been described above, but one of the light receiving lens holder 140 and the light projecting lens holder 160 may be fixed to the base frame 120 by other methods. Also, for example, while the protrusion 143 of the light receiving lens holder 140 has been described as protruding in a direction perpendicular to the arm 142, the relationship between the arm and the protrusion is not limited to this as long as the tip of the protrusion is shaped to be inserted into the adhesive stored in the recess. For example, a curved beam shape continuously formed from the arm to the protrusion may also be used.

[0043] Furthermore, in the above embodiment, the pair of arms 142 extend in a direction perpendicular to the optical axis of the light receiving lens 130, but the same effect can be expected even if the direction in which the arms extend is not perpendicular to the optical axis of the lens being held, as long as it is not parallel to the lens optical axis. For example, the pair of arms may be V-shaped or inverted V-shaped, each extending at an angle of 60 degrees to the optical axis. Also, the arm extending in one direction may be bifurcated.

[0044] [Note] Lenses (130, 150) and a frame (140, 160) for holding the lens; a base member (120) for supporting the frame; Equipped with The frame body is a pair of arms (142, 162) extending in a direction not parallel to the optical axis of the lens to be held; a protrusion (143, 163) provided to protrude from the tip of the arm toward the base member; and The base member is A flat portion (121); a raised portion (122, 125) that rises from the flat portion toward the protruding portion and has a depression (123, 126) on an upper surface (122a, 125a) for storing adhesive (200); and The tip of the protrusion is inserted into the recess and surrounded by the adhesive, thereby forming a lens support structure (100) in which the frame is supported by the base member. [Explanation of symbols]

[0045] 100... distance measuring sensor, 111... housing, 112... cable, 113... light-emitting window, 114... light-receiving window, 120... base frame, 121... bottom surface, 121a... light-receiving side bottom surface, 121b... light-emitting side bottom surface, 122... raised portion, 122a... upper surface portion, 123... recessed portion, 124... guide groove, 125... raised portion, 125a... upper surface portion, 126... recessed portion, 127... guide groove, 128... fitting frame, 129... housing Frame, 130...light receiving lens, 140...light receiving lens holder, 141...frame portion, 142...arm portion, 143...protrusion portion, 150...light projecting lens, 160...light projecting lens holder, 161...frame portion, 162...arm portion, 163...protrusion portion, 164...through hole, 170...reflection mirror, 180...light receiving sensor, 181...sensor holder, 190...light emitting element, 200...adhesive, 210...UV irradiator

Claims

1. Lenses and a frame for holding the lens; a base member supporting the frame body; Equipped with The frame body is a pair of arms extending in a direction not parallel to the optical axis of the lens to be held; a protrusion provided so as to protrude from the tip of the arm portion toward the base member; and The base member is A flat portion and a raised portion that rises from the flat portion toward the protruding portion and has a depression on its upper surface that stores adhesive; and A lens support structure in which the tip of the protrusion is inserted into the recess and surrounded by the adhesive, thereby supporting the frame on the base member, and a through hole is provided at the boundary between the arm portion and the protrusion.

2. The lens support structure according to claim 1 , wherein the upper surface portion is positioned above a lower end of the lens held by the frame.

3. 3. The lens support structure according to claim 1, wherein a groove is provided in a part of a wall portion that forms the recess, for allowing the adhesive that overflows from the recess to flow out.

4. The lens support structure according to claim 1 , wherein the length of the protrusion parallel to the optical axis direction of the lens is longer than the length of the protrusion from the arm toward the base member.

5. The adhesive includes at least an ultraviolet curable adhesive, The lens support structure according to claim 1 , wherein a surface treatment is performed so that the ultraviolet reflectance of the surface of the recess is greater than the ultraviolet reflectance of the surface of the flat portion.

6. An optical distance measuring sensor that employs a lens support structure according to any one of claims 1 to 5 as a structure for supporting at least one of a light-emitting lens arranged between a light-emitting element and a light-projecting window, and a light-receiving lens arranged between a light-receiving window and a light-receiving sensor.

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