Optical target device

Abstract

The main body of the measuring device can be easily attached to and detached from the mounting hole in the tunnel. [Solution] The optical target device 1 comprises an outer cylinder unit 10 positioned inside a mounting hole 97 formed in the inner wall 98 of the tunnel 99, and an inner cylinder unit 20 that houses the main body of the device and is detachable from the outer cylinder unit 10. The outer cylinder unit 10 has a locking structure that can be locked to the inner circumferential surface of the mounting hole 97.

Description

Technical Field

[0001] The present invention relates to an optical target device.

Background Art

[0002] Patent Documents 1 and 2 disclose a method of measuring the position of the inner wall of a tunnel by sighting targets such as prisms and mirrors installed in the tunnel with a surveying instrument.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Measurement using a surveying instrument and a target is periodically performed over a certain period in order to obtain displacement of the inner wall of a tunnel over time. Therefore, if the target can be easily attached to and detached from the inner wall of the tunnel, it is useful for efficient work. The present invention has been made in view of the above circumstances, and an object thereof is to enable an apparatus main body for measurement to be easily attached to and detached from an attachment hole in a tunnel.

Means for Solving the Problems

[0005] To achieve the above object, an optical target device according to the present invention includes an outer cylinder member disposed inside an attachment hole formed in the inner wall of a tunnel, an inner cylinder member that houses the apparatus main body and is detachable inside the outer cylinder member, and the outer cylinder member has a locking structure that can be locked to the inner peripheral surface of the attachment hole.

Effects of the Invention

[0006] According to the present invention, the main body of the measuring device can be easily attached to and detached from the mounting hole in the tunnel. [Brief explanation of the drawing]

[0007] [Figure 1] This is a cross-section of the tunnel. [Figure 2] This is an exploded perspective view of an optical target device according to an embodiment. [Figure 3] This is an exploded perspective view of the outer cylinder unit according to the embodiment. [Figure 4] This is an exploded perspective view of the inner cylinder unit according to the embodiment. [Figure 5] This is an exploded perspective view of the inner cylinder unit according to the embodiment, including the moving mechanism. [Figure 6] This diagram illustrates a method for installing an optical target device on the inner wall of a tunnel, showing the outer cylinder unit inserted into the mounting hole. [Figure 7] This diagram illustrates a method for installing an optical target device on the inner wall of a tunnel, showing the entire optical target device inserted into the mounting hole. [Figure 8] This is a diagram illustrating the method of using the optical target device according to the embodiment. [Figure 9] This is a diagram illustrating the method of using the optical target device according to the embodiment. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings. However, the scope of the present invention is not limited to the embodiments disclosed below. The drawings are provided for illustrative purposes only, and therefore the scope of the present invention is not limited to the examples shown in the drawings.

[0009] [1. Overview] Figure 1 is a cross-sectional view of the mountain tunnel 99 under construction. The cross-section in Figure 1 is perpendicular to the axial direction of the tunnel 99.

[0010] In the construction of tunnel 99, the tunnel 99 will be constructed in the mountainous area by excavating the tunnel face using blasting, etc. During construction, the movement and displacement of the inner wall 98 of tunnel 99 will be measured periodically (for example, daily) in order to judge the stability of the ground, the safety of tunnel 99, the effectiveness of the support structure, and the effectiveness of the lining.

[0011] During measurement, multiple optical target devices 1 and surveying instruments 85 are used. Multiple optical target devices 1 are arranged in the circumferential direction of the tunnel 99 and installed on the inner wall 98 of the tunnel 99. There are multiple sets of multiple optical target devices 1 arranged in the circumferential direction, and multiple sets are arranged at predetermined intervals in the axial direction of the tunnel 99. As excavation of the tunnel face progresses, additional sets are added. The surveying instruments 85 are optical sighting devices such as total stations, transits, and electro-radiography rangefinders. The surveying instruments 85 are set on the floor of the tunnel 99, and the three-dimensional position of the optical target devices 1 is measured by sighting them with the surveying instruments 85. In other words, the distance from the surveying instruments 85 to the optical target devices 1, as well as the tilt angle and pan angle, are measured by the surveying instruments 85, and the three-dimensional position of the optical target devices 1 is calculated and measured using the distance, tilt angle, and pan angle. The tilt angle refers to the elevation and depression angle of the surveying instrument 85 in the sighting direction, around a horizontal axis perpendicular to the sighting direction. The pan angle refers to the angle (azimuth angle) in the sighting direction, around a vertical axis intersecting the sighting direction. The sighting direction refers to the direction along the light rays projected by the surveying instrument 85. The position of the surveying instrument 85 may be offset in the direction of the axis of the tunnel 99 from the plane through which the multiple optical target devices 1 arranged in the circumferential direction of the tunnel 99 pass (this plane is perpendicular to the direction of the axis of the tunnel 99), or it may be aligned with that plane.

[0012] During the construction of the tunnel 99, if the optical target device 1 protrudes inside the inner wall 98 (inside the tunnel 99), the optical target device 1 will be in the way. Therefore, the optical target device 1 is devised so that it does not get in the way except during measurement. The optical target device 1 of the present embodiment is arranged in the mounting hole 97 formed in the inner wall 98, and almost the entire optical target device 1 is housed in the mounting hole 97 except during measurement.

[0013] [2. Optical Target Device] FIG. 2 is an exploded perspective view of the optical target device 1. As shown in this figure, the optical target device 1 includes an outer cylinder unit 10 and an inner cylinder unit 20. The outer cylinder unit 10 corresponds to an example of the outer cylinder member according to the present invention, and the inner cylinder unit 20 corresponds to an example of the inner cylinder member according to the present invention. The outer cylinder unit 10 and the inner cylinder unit 20 are formed in corresponding cylindrical shapes, and the outer cylinder unit 10 removably houses the inner cylinder unit 20 inside. Hereinafter, the direction along the central axis Ax of the outer cylinder unit 10 is referred to as the "axial direction", the direction perpendicular to the central axis Ax is referred to as the "radial direction", and the rotational direction centered on the central axis Ax is referred to as the "circumferential direction". Also, among the axial directions, the opening side of the outer cylinder unit 10 (the left side in FIG. 2) is referred to as the "front side (front)", and the side opposite to the front side (the right side in FIG. 2) is referred to as the "rear side (rear)".

[0014] (1) Outer Cylinder Unit FIG. 3 is an exploded perspective view of the outer cylinder unit 10. As shown in this figure, the outer cylinder unit 10 has an outer cylinder case 11, a cap end 12, a lock fastener 13, and a stopper 14. The outer cylinder case 11 is formed in a long cylindrical shape in the axial direction, and both ends in the axial direction are open. The outer cylinder case 11 of the present embodiment is made of resin such as polyvinyl chloride, for example, and has an outer diameter of 42 mm.

[0015] The cap end 12 is attached to the rear end of the outer cylinder case 11 and closes the rear end opening. The cap end 12 is secured to the outer cylinder case 11 by a screw 18a. The gap between the cap end 12 and the outer cylinder case 11 is sealed by an O-ring 15.

[0016] The lock fastener 13 is a metal component for holding the outer cylinder unit 10 in the mounting hole 97 of the tunnel 99, and is attached to the rear end of the cap end 12. Specifically, the lock fastener 13 has a ring portion 131 and a number of (three in this embodiment) legs 132. The ring portion 131 is formed in a cylindrical shape along the axial direction and is inserted through the shaft portion 121 of the cap end 12 from the rear. The ring portion 131 is held almost concentrically with the outer cylinder case 11 via the cap end 12. With the ring portion 131 inserted through the shaft portion 121 of the cap end 12, a nut 16 is fastened to the threaded portion 122 on the tip side (rear end side) of the shaft portion 121, thereby clamping the cap end 12 and the nut 16 in the axial direction. This fixes the lock fastener 13 and the cap end 12.

[0017] The multiple legs 132 are elastic plates extending forward from the front end of the ring portion 131. The base ends of the multiple legs 132 are arranged equally on the circumferential edge of the front end of the ring portion 131. Each leg 132 is formed in a thin plate shape perpendicular to a plane passing through the central axis Ax and along the axial direction, and its front end is deformable along this plane. When each leg 132 is not inserted into the mounting hole 97 of the tunnel 99, its front end is bent (deformed) to a radial position larger than the diameter of the mounting hole 97. Therefore, as will be described later, when each leg 132 is inserted into the mounting hole 97, it exerts a biasing force in the outward radial direction due to its elasticity and can be locked into the inner circumferential surface of the mounting hole 97.

[0018] The stopper 14 is a cylindrical resin component that is fixed to the front end of the outer cylinder case 11. The stopper 14 is fitted over the outer circumference of the outer cylinder case 11 and fixed to the outer cylinder case 11 by screws 18b. At the front end of the stopper 14, a flange-shaped portion 141 is formed that protrudes outward and extends almost all the way around. The outer diameter of the flange portion 141 is, for example, 55 mm or more.

[0019] Multiple convex fins 142 are erected on approximately the rear half of the outer circumferential surface of the stopper 14, projecting outwards toward the outer diameter. The multiple fins 142 are arranged in parallel in the radial direction, and each is formed over approximately the entire circumference of the stopper 14. Each fin 142 only needs to extend along a direction intersecting the axial direction.

[0020] Multiple (three in this embodiment) wedge grooves 143 are formed on the outer circumferential surface of the stopper 14 at equal intervals. Each wedge groove 143 is formed along the axial direction with a predetermined groove width perpendicular to the radial direction, and is formed by machining the flange portion 141 and fin 142 at the corresponding position. As will be described later, the wedge grooves 143 are grooves into which wedges 17 can be inserted to reinforce the holding of the outer cylinder unit 10 in the mounting hole 97 of the tunnel 99.

[0021] (2) Inner cylinder unit Figure 4 is an exploded perspective view of the inner cylinder unit 20. As shown in this figure, the inner cylinder unit 20 comprises an inner cylinder case 21, a battery 31, a control board 35, a top tube 41, a retroreflector 45, and a moving mechanism 50. The main body of the device according to the present invention includes at least the retroreflector 45.

[0022] The inner cylinder case 21 is formed in an axially elongated cylindrical shape with an open front end. The inner cylinder case 21 is formed in a cylindrical shape that is slightly smaller than the outer cylinder case 11 and can be inserted concentrically into the outer cylinder case 11 (outer cylinder unit 10). The rear end of the inner cylinder case 21 is closed by a lid member 22 (see Figure 2, etc.). The lid member 22 has a threaded portion 222 that is erected facing rearward and screws onto the cap end 12 (boss 125) of the outer cylinder unit 10.

[0023] The battery 31 is located at the rear of the inner cylinder case 21, detachably housed in the battery holder 32. The battery holder 32 is secured to the inner cylinder case 21 by screws 23a. All holes in the inner cylinder case 21 through which the screws 23a are inserted are waterproofed. The battery 31 may be a primary battery or a rechargeable secondary battery (battery).

[0024] The control board 35 is housed in the inner cylinder case 21 while being held in the battery holder 32. The control board 35 has a motor control circuit and the like mounted on it. The motor control circuit controls the operation of the motor 52 of the moving mechanism 50, which will be described later.

[0025] A communication module board 36 is located in front of the control board 35. The communication module board 36 has a communication circuit mounted on it for communicating with the remote controller 80 (described later), and is electrically connected to the communication antenna 37. In this embodiment, the communication antenna 37 is a film antenna and is located on the outer surface of the top tube 41. The communication antenna 37 transmits and receives radio waves to and from the remote controller 80. The communication module board 36 demodulates the radio waves received by the communication antenna 37 and outputs them to the control board 35, or outputs transmission signals based on control commands from the control board 35 to the communication antenna 37.

[0026] The top tube 41 is formed in a cylindrical shape and is housed in the inner cylinder case 21 at its front end. The top tube 41 has a flange-shaped portion 411 at its front end. The flange portion 411 has a larger outer diameter than the inner cylinder case 21, and its rear surface abuts against the front end surface of the inner cylinder case 21. An O-ring 42 is placed in a groove on the rear surface of the flange portion 411, and the O-ring 42 seals the space between the outer cylinder unit 10 and the top tube 41 (see Figure 8). A light-emitting element (e.g., an LED) 43 is mounted on the front surface of the flange portion 411. The light-emitting element 43 emits light when power is supplied from the battery 31 via the control board 35.

[0027] The retroreflector 45 is located at the front end of the inner cylinder unit 20. The retroreflector 45 has, for example, at least one prism and retroreflects light rays incident from various directions. The retroreflector 45 is configured to be axially movable so that it can be in a retracted state, stored inside the top tube 41, or in an exposed state, exposed in front of the top tube 41. A slider 46 is attached to the rear surface of the retroreflector 45, which is axially slidable between it and the inner circumferential surface of the top tube 41. The slider 46 is guided by the top tube 41 and moves axially together with the retroreflector 45. A rubber seal ring 47 (see Figure 5, etc.) is positioned at the rear of the slider 46, and the seal ring 47 seals the space between the slider 46 and the top tube 41.

[0028] A cap 48 is attached to the retroreflector 45. The cap 48 is formed in the shape of a short disc and is fixed to the front of the retroreflector 45 so as to cover the front of the retroreflector 45. When the retroreflector 45 is in the retracted state, the outer circumference of the cap 48 abuts against the front of the top tube 41, closing the front opening of the top tube 41 (see Figure 8). Light-transmitting windows 481 are formed on the cap 48 at radial and circumferential positions corresponding to the light-emitting elements 43. Therefore, even when the retroreflector 45 is in the retracted state, the light from the light-emitting elements 43 can be seen from the front through the light-transmitting windows 481.

[0029] Furthermore, the cap 48 may be made of an insulator such as resin so as not to block the radio waves propagating between the communication antenna 37 and the remote controller 80. In addition, the inner cylinder case 21 and the outer cylinder case 11 may also be made of an insulator. However, if the inner cylinder case 21 and the outer cylinder case 11 are made of a conductor such as metal, radio waves between the communication antenna 37 and the remote controller 80 are less likely to leak to the outside of the outer cylinder case 11, thus enabling suitable communication with the remote controller 80.

[0030] Figure 5 is an exploded perspective view of the inner cylinder unit 20, including the moving mechanism 50 and the retroreflector 45. However, Figure 5 omits the illustration of the cover 59 (see Figure 4) that covers the motor 52 and other components, which will be described later. As shown in Figure 5, the moving mechanism 50 is an electric actuator that moves the retroreflector 45 in the axial direction. The moving mechanism 50 is positioned in the axial direction between the top tube 41 and the battery holder 32 within the inner cylinder case 21. Specifically, the moving mechanism 50 includes a linear guide 51, a motor 52, a lead screw 54, a carriage 55, and a fixing member 58.

[0031] The linear guide 51 is formed to be elongated in the axial direction and is fixed to the inner cylinder case 21. The motor 52 is fixed to the rear side of the linear guide 51. The motor 52 is, for example, a DC motor. The lead screw 54 is positioned in front of the motor 52, extending along the axial direction. The lead screw 54 is connected to the drive shaft of the motor 52 via a torque limiter 53. Therefore, if the load torque acting from the lead screw 54 to the torque limiter 53 is outside a predetermined range, the torque limiter 53 disconnects the connection between the lead screw 54 and the motor 52.

[0032] The carriage 55 is supported by a linear guide 51 so as to be movable in the axial direction. The carriage 55 has a female thread (not shown) that screws into the lead screw 54 and moves axially as the lead screw 54 rotates. The front end of the carriage 55 is fixed to the retroreflector 45 via a slider 46. Therefore, as the lead screw 54 rotates, the carriage 55 moves axially together with the retroreflector 45. In the following, the rotation of the lead screw 54 and motor 52 that moves the retroreflector 45 and carriage 55 forward will be referred to as "forward rotation," and the rotation of the lead screw 54 and motor 52 that moves the retroreflector 45 and carriage 55 backward will be referred to as "reverse rotation."

[0033] The fixing member 58 is formed to be elongated in the axial direction and is positioned to cover the lead screw 54 and fixed to the linear guide 51. A first stopper 58a and a second stopper 58b are attached to the surface of the fixing member 58 facing the linear guide 51. The first stopper 58a and the second stopper 58b contact a projection 55a protruding from the rear end of the carriage 55, thereby restricting the movement of the carriage 55. The first stopper 58a is located at the front end of the fixing member 58 and restricts the forward movement of the carriage 55. The second stopper 58b is located at the rear end of the fixing member 58 and restricts the rearward movement of the carriage 55.

[0034] The projection 55a, the first stopper 58a, and the second stopper 58b are made of a conductive material. The projection 55a and the first stopper 58a and the second stopper 58b are grounded or energized such that their voltage levels are different, one high and the other low. Therefore, when the projection 55a comes into contact with the first stopper 58a or the second stopper 58b, the voltage level of one of them, which was set to a high level, changes to a low level. The motor control circuit of the control board 35 detects contact between the projection 55a and the first stopper 58a or the second stopper 58b by monitoring the voltage of one or both of the first stopper 58a and the second stopper 58b and the projection 55a.

[0035] (3) Remote controller As shown in Figure 1, the optical target device 1 is remotely controlled by a remote controller 80. The remote controller 80 includes a retraction switch, an deployment switch, a communication device, and a communication antenna. When the operator operates the retraction switch, the remote controller 80 transmits a retraction command to the optical target device 1 via the communication device and communication antenna. Similarly, when the operator operates the deployment switch, the remote controller 80 transmits a deployment command to the optical target device 1 via the communication device and communication antenna.

[0036] [3. Method for setting up the optical target device] Figures 6 and 7 are cross-sectional views of mounting holes 97 for illustrating the method of installing the optical target device 1 on the inner wall 98 of the tunnel 99. Figure 6 shows the outer cylinder unit 10 inserted into the mounting hole 97, and Figure 7 shows the entire optical target device 1 inserted into the mounting hole 97. As shown in Figure 1, once tunnel excavation has progressed, multiple mounting holes 97 are drilled into the inner wall of the tunnel 99 at intervals in the circumferential direction. The mounting holes 97 are located away from the tunnel face but close to it. In this embodiment, the mounting hole 97 has a diameter of 45 mm, corresponding to the outer diameter of the outer cylinder unit 10 (outer cylinder case 11) which is 42 mm. Therefore, a φ45 mm bit can be used to drill holes for inserting lock bolts into the tunnel 99. In other words, a bit specifically for machining the mounting hole 97 for installing the optical target device 1 is not required.

[0037] Next, as shown in Figure 6, the outer cylinder unit 10 of the optical target device 1 is inserted into each mounting hole 97. Here, with the rear end of the lock fastener 13 facing the back of the mounting hole 97, the outer cylinder unit 10 is inserted into the mounting hole 97. Then, the flange portion 141 of the stopper 14 is brought into contact with the inner wall 98 of the tunnel 99 at the opening of the mounting hole 97. As a result, almost the entire outer cylinder unit 10 is inserted into the mounting hole 97.

[0038] At this time, the diameter of the mounting hole 97 is 45 mm, and the outer diameter of the outer cylinder unit 10 (outer cylinder case 11) is 42 mm. Therefore, even including various machining errors, the mounting hole 97 is neither particularly large nor small compared to the outer cylinder unit 10, and the outer cylinder unit 10 can be inserted into the mounting hole 97 in a generally suitable manner.

[0039] At this time, the outer cylinder unit 10 is suitably locked to the inner circumferential surface of the mounting hole 97 by the locking structure provided by the outer cylinder unit 10. Here, "locking" means preventing the outer cylinder unit 10 from moving in the axial direction relative to the mounting hole 97. First, at the rear side of the outer cylinder unit 10 (the side behind the mounting hole 97), the multiple legs 132 of the lock fastener 13 are bracing the inner circumferential surface of the mounting hole 97 with their elastic force. As a result, the movement of the outer cylinder unit 10 is suppressed. Furthermore, since the tip (rear end) of each leg 132 is facing the opening side of the mounting hole 97, the tip catches on the inner circumferential surface of the mounting hole 97, preventing the outer cylinder unit 10 from moving in the direction of falling out of the mounting hole 97. Furthermore, on the front side of the outer cylinder unit 10 (the opening side of the mounting hole 97), multiple fins 142 protruding from the outer circumferential surface of the stopper 14 deform and come into contact with the inner circumferential surface of the mounting hole 97. This suppresses axial movement of the outer cylinder unit 10, that is, movement in the direction of falling out of the mounting hole 97. Therefore, since the mounting hole 97 is easily formed with a larger opening side than the inner side, the outer cylinder unit 10 can be suitably fixed on the opening side. Furthermore, if you want to secure the outer cylinder unit 10 more firmly, you may insert a wedge 17 between the stopper 14 and the mounting hole 97 (see Figure 8). In this case, when the outer cylinder unit 10 is placed in the mounting hole 97, the wedge 17 should be inserted into each wedge groove 143 on the outer surface of the stopper 14 that is exposed at the opening of the mounting hole 97. The outer cylinder unit 10 only needs to be equipped with at least one of these locking structures.

[0040] Next, as shown in Figure 7, the inner cylinder units 20 are inserted into the outer cylinder units 10 with each mounting hole 97. Here, first, the power switch (not shown) is turned ON so that the control board 35 and other components are powered by the battery 31. Then, with the cover member 22 facing the back of the mounting hole 97, the inner cylinder unit 20 is inserted into the outer cylinder unit 10. The inner cylinder unit 20 is then fixed to the outer cylinder unit 10 by fastening the threaded portion 222 at the rear end of the cover member 22 to the threaded hole of the boss 125 on the outer cylinder unit 10. At this time, in the normal state where the retroreflector 45 is not exposed (storage state), the cap 48 of the inner cylinder unit 20 is exposed on the inside of the tunnel 99 so as to close the opening of the mounting hole 97. In addition, the space between the outer cylinder unit 10 and the inner cylinder unit 20 is sealed by the O-ring 42 located on the rear surface of the flange portion 411 of the top tube 41 (see Figure 8).

[0041] The inner cylinder unit 20 is detachable from the outer cylinder unit 10 by screwing in the threaded portion 222, and can be removed from the outer cylinder unit 10 and recovered, for example, at the end of the construction period. In this case, the outer cylinder unit 10 may be buried inside the tunnel 99. In this case, it is desirable that the outer cylinder unit 10 be made of a particularly simple structure and inexpensive materials. Also in this case, each part of the outer cylinder unit 10 may be made of environmentally friendly materials such as biomass plastic or biodegradable plastic.

[0042] [4. How to use the optical target device] Figures 8 and 9 are diagrams illustrating the method of using the optical target device 1. When not measuring the inner wall 98 of tunnel 99, the optical target device 1 is in its normal state (storage state) with the retroreflector 45 retracted, as shown in Figure 8. Here, times other than when measuring include, for example, when excavating tunnel 99, when bringing in materials, when removing materials, when constructing shoring, when removing shoring, when constructing lining, and when performing spraying work.

[0043] To begin measurement, the operator first sets the optical target device 1 so that the retroreflector 45 is exposed (exposed state). At this time, when the operator operates the deployment switch on the remote controller 80, a deployment command is transmitted from the remote controller 80 to the control board 35 of the optical target device 1. The motor control circuit of the control board 35 then rotates the motor 52 of the moving mechanism 50 in the forward direction, moving the retroreflector 45 towards the opening of the mounting hole 97. When the projection 55a of the carriage 55 hits the first stopper 58a, the load torque acting on the torque limiter 53 exceeds a predetermined value, and the connection between the lead screw 54 and the motor 52 is disconnected. At the same time, the voltage level of the projection 55a or the first stopper 58a changes (for example, a voltage drop), and the motor control circuit stops the motor 52 using this voltage change as a trigger. Thus, as shown in Figure 9, the retroreflector 45 is exposed into the tunnel 99 from inside the mounting hole 97.

[0044] Subsequently, the worker sets up the surveying instrument 85 inside the tunnel 99. Then, the surveying instrument 85 projects a beam of light onto the retroreflector 45 of the optical target device 1. The beam of light is retroreflected by the retroreflector 45, and the reflected beam is received by the surveying instrument 85. The surveying instrument 85 measures the distance to the retroreflector 45, as well as the tilt angle and pan angle, and calculates the three-dimensional position of the retroreflector 45 based on these measurements.

[0045] After the measurement is complete, the operator returns the optical target device 1 to the retracted state (retracted state) with the retroreflector 45 retracted. At this time, when the operator operates the retraction switch on the remote controller 80, a retraction command is transmitted from the remote controller 80 to the control board 35 of the optical target device 1. The motor control circuit of the control board 35 then reverses the rotation of the motor 52 of the moving mechanism 50, moving the retroreflector 45 to the back of the mounting hole 97. When the projection 55a of the carriage 55 hits the second stopper 58b, the load torque acting on the torque limiter 53 exceeds a predetermined value, and the connection between the lead screw 54 and the motor 52 is disconnected. At the same time, the voltage level of the projection 55a or the second stopper 58b changes, and the motor control circuit uses this voltage change as a trigger to stop the motor 52.

[0046] In this way, the retroreflector 45 is housed inside the top tube 41, and the opening of the top tube 41 is closed by the cap 48. In this configuration, only the cap 48 is exposed inside the tunnel 99, while most of the optical target device 1, especially the retroreflector 45, is contained within the mounting hole 97. Therefore, the optical target device 1 does not interfere with the construction work of the tunnel 99. Furthermore, the retroreflector 45 can be protected from debris generated by blasting at the tunnel face. Furthermore, even when the retroreflector 45 is retracted, the worker can see the light from the light-emitting element 43 of the top tube 41 through the light-transmitting window 481 of the cap 48, and thus determine the position of the optical target device 1. This is particularly effective when the inside of the tunnel 99 is dark.

[0047] [5. Technical Effects of this Embodiment] According to this embodiment, the outer cylinder unit 10 (outer cylinder member) positioned inside the mounting hole 97 of the tunnel 99 has a locking structure that can engage with the inner circumferential surface of the mounting hole 97. In addition, the inner cylinder unit 20 (inner cylinder member) that houses the main body of the device including the retroreflector 45 is detachably attached to the outer cylinder unit 10. Therefore, the inner cylinder unit 20 can be attached to and detached from the outer cylinder unit 10, which is held in place in the mounting hole 97 by the locking structure. Consequently, the main body of the device can be easily attached to and detached from the mounting hole 97 compared to the case where a target such as a prism mirror is directly attached to the mounting hole. In other words, the main body of the measuring device can be easily attached to and detached from the mounting hole 97 of the tunnel 99.

[0048] Furthermore, according to this embodiment, the locking structure of the outer cylinder unit 10 includes a plurality of legs 132 (elastic plates) that are biased in the outer diameter direction of the outer cylinder unit 10 and can be locked to the inner circumferential surface of the mounting hole 97. Therefore, the movement of the outer cylinder unit 10 can be suppressed by bracing the inner circumferential surface of the mounting hole 97 with multiple legs 132. Thus, the outer cylinder unit 10 can be suitably locked into the mounting hole 97.

[0049] Furthermore, according to this embodiment, the locking structure of the outer cylinder unit 10 includes fins 142 (elastic fins) that are erected on the outer circumferential surface of the outer cylinder unit 10 and extend in a direction intersecting the axial direction. Therefore, the fins 142 suppress the axial movement of the outer cylinder unit 10, that is, movement in the direction that would cause it to fall out of the mounting hole 97. Thus, the outer cylinder unit 10 can be securely locked into the mounting hole 97.

[0050] Furthermore, according to this embodiment, the locking structure of the outer cylinder unit 10 includes a wedge groove 143 (groove) formed axially on the outer circumferential surface of the end of the outer cylinder unit 10 on the opening side of the mounting hole 97, into which the wedge 17 can be inserted. The wedge groove 143 is exposed to the opening of the mounting hole 97 when the outer cylinder unit 10 is placed in the mounting hole 97. Therefore, with the outer cylinder unit 10 positioned in the mounting hole 97, the wedge 17 can be inserted between the outer cylinder unit 10 and the inner circumferential surface of the mounting hole 97 along the wedge groove 143, thereby fixing the outer cylinder unit 10 to the mounting hole 97. Thus, the outer cylinder unit 10 can be suitably locked into the mounting hole 97.

[0051] Furthermore, according to this embodiment, the outer diameter of the outer cylinder unit 10 is of a size corresponding to a hole different from the mounting hole 97 formed in the inner wall 98 of the tunnel 99, and is, for example, of a size corresponding to a hole in the tunnel 99 into which a lock bolt is inserted. Therefore, for example, the mounting hole 97 can be formed using a φ45 mm bit for drilling the hole. In other words, a special tool for processing the mounting hole 97 for installing the optical target device 1 can be eliminated. Furthermore, the outer diameter of the outer cylinder unit 10 does not need to be a size that corresponds to a hole other than the mounting hole 97 formed in the inner wall 98 of the tunnel 99. In other words, the outer diameter of the outer cylinder unit 10 may be a size that corresponds to a hole other than the hole for inserting the rock bolt, which is formed during tunnel construction.

[0052] Furthermore, according to this embodiment, the main body of the device housed in the inner cylinder unit 20 includes a retroreflector 45 and a moving mechanism 50 that moves the retroreflector 45 to extend and retract it from inside the inner cylinder unit 20. As a result, when not in use, the retroreflector 45 is stored inside the mounting hole 97, so it does not interfere with tunnel construction work. Also, debris and equipment from blasting at the tunnel face will not hit the retroreflector 45. Therefore, there is no need to remove the retroreflector 45 and the optical target device 1 from the inner wall 98 of the tunnel 99. Consequently, there is no need to install and remove the retroreflector 45 and the optical target device 1 each time a measurement is taken. Thus, the effort and labor involved in taking measurements can be minimized. In addition, there is no need to perform work at height each time a measurement is taken, and measurements of the inner wall 98 of the tunnel 99 can be performed safely.

[0053] [6. Others] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above. For example, in the above embodiment, communication between the remote controller 80 and the optical target device 1 was wireless, but such communication may also be wired. Furthermore, the specific configuration of the moving mechanism 50 is not particularly limited, as long as it can move the retroreflector 45 in the axial direction. Moreover, the inner cylinder unit 20 only needs to be able to hold the retroreflector 45 against the inner wall 98 of the tunnel 99, and the retroreflector 45 does not need to be able to extend and retract. Furthermore, the main body of the apparatus according to the present invention may include an optical target that can be used for measuring the inner wall of a tunnel, and this optical target does not have to be a retroreflector.

[0054] Furthermore, in the above embodiment, the tunnel 99 is under construction. In contrast, after the completion of the construction work on the tunnel 99, the inner wall 98 of the tunnel 99 can be measured using the surveying instrument 85 and the optical target device 1. Furthermore, by machining mounting holes in the inner wall of an existing tunnel and fitting the optical target device 1 into these mounting holes, the inner wall of the existing tunnel can be measured using the surveying instrument 85 and the optical target device 1.

[0055] Furthermore, details shown in the above embodiments can be modified as appropriate without departing from the spirit of the invention. [Explanation of Symbols]

[0056] 1 Optical targeting device 10. Outer cylinder unit (outer cylinder member) 13 Lock fasteners 132 Leg section (elastic plate, locking structure) 14 Stopper 142 fins (elastic fins, locking structure) 143 Wedge groove (groove, locking structure) 17 Wedge 20 Inner cylinder unit (inner cylinder member) 45 Retroreflector (main unit of the device) 50 Moving mechanism 97 Mounting holes 98 Inner wall 99 Tunnel Ax center axis

Claims

1. An outer cylindrical member positioned inside a mounting hole formed in the inner wall of the tunnel, The main body of the device is housed within the outer cylindrical member, and the inner cylindrical member is removable from the outer cylindrical member, Equipped with, The outer cylindrical member has a locking structure that can engage with the inner circumferential surface of the mounting hole. Optical targeting device.

2. The locking structure includes a plurality of elastic plates that are biased in the outer diameter direction of the outer cylinder member and can be locked to the inner circumferential surface of the mounting hole. The optical target device according to claim 1.

3. The locking structure includes elastic fins erected on the outer circumferential surface of the outer cylinder member and extending in a direction intersecting the axial direction of the outer cylinder member. The optical target device according to claim 1.

4. The elastic fin is positioned at the end of the outer cylinder member on the side of the opening of the mounting hole. The optical target device according to claim 3.

5. The locking structure includes a groove formed on the outer circumferential surface of the end of the outer cylinder member on the opening side of the mounting hole, along the axial direction of the outer cylinder member, into which a wedge can be inserted. The groove is exposed to the opening of the mounting hole when the outer cylindrical member is positioned in the mounting hole. The optical target device according to claim 1.

6. The outer diameter of the outer cylinder member is of a size corresponding to a hole different from the mounting hole formed in the inner wall of the tunnel. The optical target device according to claim 1.

7. The main body of the device is, Retroreflector, A moving mechanism that moves the retroreflector to extend and retract it from inside the inner cylindrical member, including, The optical target device according to claim 1.

Images