JP2006003117A - Contact type displacement sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contact type displacement sensor allowing pushing-in of a movable part without interference of a spring energizing the movable part with a bobbin. <P>SOLUTION: This contact type displacement sensor comprises: an exciting coil 12 generating a detection signal; the bobbin 13 installed with the exciting coil 12, and axially formed with a hollow part; the movable part formed with a core inserted into the hollow part at one end, and formed with a contact 4 at the other end axially projecting from the bobbin 13; and the coil-like spring 11 disposed coaxially with the movable part, the whole of which is stored inside the hollow part, and axially energizing the movable part. Especially, in the spring 11, a difference between a diameter of the hollow part and an outside diameter of the spring 11 is smaller than a difference between an inside diameter of the spring 11 and a diameter of a core holding tube 14. The movable part comprises: a core holder part 15 holding the core, and abutting on the tip of the spring 11; a shaft part 17 provided with the contact 4; and a connection part 18 bendably connecting the core holder part 15 and the shaft part 17. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a contact-type displacement sensor, and more specifically, a core is formed at one end of a movable part and a contact is formed at the other end, corresponding to the position of the core in a bobbin on which an exciting coil is mounted. The present invention relates to an improvement of a contact-type displacement sensor using a differential transformer or the like that generates a detection signal.

  As a displacement sensor that detects the amount of displacement in real time following the displacement of the measurement object, there is a contact displacement sensor that uses a differential transformer or the like. A contact-type displacement sensor usually has a bobbin on which an excitation coil for generating a detection signal is mounted, a core inserted into the bobbin at one end, a movable part with a contact at the other end, and a movable part. It consists of a coil-like spring that urges the shaft in the axial direction. The spring is provided to apply a restoring force to the movable portion when the contact is pushed in the axial direction following the displacement of the measurement target. In the so-called pencil-type contact displacement sensor, the spring is arranged coaxially with the movable part in order to simplify the shape of the device and make the device compact. In such a contact-type displacement sensor, a detection signal corresponding to the position of the core in the bobbin is generated by the exciting coil.

  FIG. 7 is a plan view showing the appearance of a conventional contact displacement sensor. FIG. 8 is a diagram showing details of the main part of the contact-type displacement sensor of FIG. 7, and the movable part 104 and the spring inserted into the bobbin 106 when the contact 105 is pushed in the axial direction. 109 is shown. The contact displacement sensor 100 is a pencil type displacement sensor, and a bobbin 106 is mounted in a cylindrical housing 103. An excitation coil 107 that generates a detection signal is attached to the bobbin 106, and a hollow portion 111 is formed in the axial direction. The detection signal generated by the excitation coil 107 is transmitted to an external device such as a controller via the cable 101 connected to the case 102 of the indicator lamp provided at the rear end of the housing 103.

  A core holding tube 108 that holds a core (magnetic core) inserted into the hollow portion 111 is attached to one end of the movable portion 104, and the other end that protrudes in the axial direction from the bobbin 106 is brought into contact with the measurement object. A child 105 is attached. The spring 109 is disposed coaxially with the core holding tube 108 of the movable portion 104 and urges the movable portion 104 in the axial direction. The spring 109 has a natural length (natural length) longer than the axial length of the bobbin 106, and a part of the spring 109 protrudes from the bobbin 106 and is disposed in the hollow portion 111. The tip of the spring 109 is in contact with a spring receiving part 110 provided on the movable part 104. That is, when the movable portion 104 is pushed through the contact 105, the spring 109 biases the spring receiving portion 110 in the axial direction so that it can be operated following the displacement of the measurement target.

  However, in the conventional contact displacement sensor described above, when the movable portion 104 is pushed in, the spring 109 meanders between the bobbin 106 and the spring receiving portion 110, so that the meandering spring 109 interferes with the bobbin 106. There was a problem. The term “interference” as used herein refers to contact involving wear or catching abnormal noise. The interference between the spring 109 and the bobbin 106 is caught when the movable part 104 enters the hollow part 111, which not only prevents smooth sliding of the movable part 104 but also causes abnormal noise, Is made of resin, there is a problem that the vicinity of the entrance of the hollow portion 111 of the resin bobbin is scraped by the metallic spring 109. Further, when the meandering spring 109 comes into contact with the core holding tube 108 at the contact portion 112 or the like, a force perpendicular to the axial direction (lateral direction) is applied to the core holding tube 108. When this lateral force is applied, the core holding tube 108 is shaken, which causes a problem in that the detected displacement value varies.

  In order to prevent the spring urging the movable part from interfering with the bobbin, it is conceivable to provide the entire spring outside the bobbin. That is, it is conceivable that a spring is disposed between the bobbin and the spring receiving portion so that one end of the spring is brought into contact with the end surface of the bobbin and the other end is brought into contact with the spring receiving portion.

  FIG. 9 is a diagram showing details of a main part of the contact-type displacement sensor, and shows a state of the spring 121 arranged between the bobbin 106 and the spring receiving part 122. By disposing the spring 121 between the bobbin 106 and the spring receiving portion 122, it is possible to prevent the spring 121 from interfering with the bobbin 106. However, since the spring 121 is provided between the bobbin and the spring receiving portion 122, the length of the core holding tube 108 is the length of the spring 121 when the spring 121 is most contracted, that is, the minimum value of the length of the spring 121. There was a problem that would become longer.

  Generally, in a contact displacement sensor, it is desirable that the restoring force by a spring is constant within the movable range of the movable part. For this reason, if the diameter and the pitch are the same, a spring having a longer natural length, that is, a spring having a smaller spring constant (elastic constant) is used. In the contact type displacement sensor described above, specifically, if the natural length is 120 mm, the minimum value of the length of the spring 121 is 20 to 30 mm, and the length of the core holding tube 108, that is, the movable length is movable by this length. Since the length of the portion 104 is increased, there is a problem that the total length of the sensor body is increased.

  In order to prevent the spring from meandering between the bobbin and the spring receiving part when the movable part is pushed in, it is conceivable to reduce the diameter of the spring. That is, it is conceivable to reduce the diameter of the spring so that the core holding tube 108 serves as a guide.

FIG. 10 is a diagram showing details of a main part of the contact-type displacement sensor, and shows a state of the spring 131 using the core holding tube 108 as a guide. By using the core holding tube 108 as a guide, the spring 131 can be prevented from meandering between the bobbin 106 and the spring receiving portion 110. However, since the diameter of the spring 131 is small, there is a problem that a gap between the inner wall surface of the bobbin 106 and the spring 131 becomes large, and a part of the spring 131 protruding from the core holding tube 108 meanders in the hollow portion. When a part of the spring 131 to meander comes into contact with the tip of the core holding tube 108, a lateral force is applied to the core holding tube 108, so that the core holding tube 108 is shaken, and the detected value of the displacement amount is obtained. There was a problem that variations such as value jumps occurred.
JP 2002-357404 A JP 2001-188001 A

  As described above, the conventional contact displacement sensor has a problem that when the movable part is pushed in, the spring meanders between the bobbin and the spring receiving part and interferes with the bobbin. Further, when the meandering spring comes into contact with the core holding tube, there is a problem in that the core holding tube is shaken and the detection value of the displacement amount varies.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a contact-type displacement sensor that can push a movable part without causing a spring that biases the movable part to interfere with the bobbin. . In particular, it is an object of the present invention to provide a contact-type displacement sensor that prevents the spring from meandering outside the bobbin and suppresses variations in the detected amount of displacement.

  It is another object of the present invention to provide a contact-type displacement sensor that can prevent interference between a spring and a bobbin without increasing the total length of the sensor body. It is another object of the present invention to provide a contact type displacement sensor that suppresses meandering of a spring in a bobbin.

  Another object of the present invention is to provide a contact-type displacement sensor in which excessive force is not applied to each part during assembly of the sensor body. In particular, an object of the present invention is to provide a contact type displacement sensor that suppresses interference of the front end of the movable part with the inner wall surface of the bobbin when the bobbin and the movable part are assembled from the opposite sides of the cylindrical casing.

  The contact displacement sensor according to the present invention has an excitation coil that generates a detection signal, a bobbin that is mounted with the excitation coil and has a hollow portion formed in the axial direction, and a core that is inserted into the hollow portion at one end. A movable portion having a contact formed at the other end protruding from the bobbin in the axial direction, and the movable portion is coaxially disposed with the movable portion and is always accommodated in the hollow portion, and the movable portion is axially disposed. It is composed of a coiled spring that biases.

  The contact displacement sensor according to the present invention is configured such that, in addition to the above configuration, the spring has a diameter substantially the same as the diameter of the hollow portion.

  In the contact displacement sensor according to the present invention, in addition to the above configuration, the spring has a difference between the diameter of the hollow portion and the outer diameter of the spring smaller than the difference between the inner diameter of the spring and the diameter of the core forming portion of the movable portion. It is comprised so that it may become.

  In addition to the above-described configuration, the contact-type displacement sensor according to the present invention includes a core holder portion in which the movable portion holds the core and abuts against a tip of the spring, a shaft portion on which the contact is provided, and the core holder And a connecting part that connects the shaft part so as to be bendable.

  In particular, the connecting portion is configured to be connected via an adhesive member having elasticity. Further, it is configured to include a cylindrical casing on which the bobbin is mounted, and a bearing formed in the casing and slidably holding the shaft portion.

  According to the contact-type displacement sensor of the present invention, the spring for urging the movable portion in the axial direction is disposed so as to be entirely accommodated in the hollow portion of the bobbin, thereby preventing the spring from meandering outside the bobbin. Can do. Therefore, the core of the movable part can be pushed into the hollow part without the spring interfering with the bobbin. That is, the core can be pushed into the hollow portion without causing contact with wear or hooking noise. Moreover, since the whole spring is accommodated in the bobbin, the interference between the spring and the bobbin can be prevented without increasing the total length of the sensor body.

  In particular, since the difference between the diameter of the hollow portion and the outer diameter of the spring is smaller than the difference between the inner diameter of the spring and the diameter of the core forming portion in the movable portion, the spring is effectively suppressed from meandering in the bobbin. be able to. Accordingly, since it is possible to prevent a lateral force from being applied to the core forming portion of the movable portion due to the meandering of the spring, it is possible to suppress the variation in the detected value of the displacement amount.

  Moreover, since the core holder part and shaft part which contact | abut to the front-end | tip of a spring are connected so that bending is possible, it can suppress that an excessive force is applied to each part at the time of an assembly of a sensor main body. In particular, when a bearing that slidably holds a shaft portion is formed in a cylindrical housing, assembly errors that occur when a bearing or the like is assembled in the housing can be absorbed by the connecting portion. It can suppress effectively that a core holder part interferes with the inner wall face of a hollow part.

Embodiment 1 FIG.
FIG. 1 is an external perspective view showing an example of a displacement measuring device including a contact-type displacement sensor according to Embodiment 1 of the present invention, and a detection signal based on the displacement of a movable part 3 that follows the displacement of a measuring object A. The state of the contact-type displacement sensor 2 and the controller 7 that generate the signal is shown. The displacement measuring device 1 includes a contact-type displacement sensor 2 and a controller 7 and performs an operation of detecting the displacement amount in real time following the displacement of the measurement target A.

  The contact-type displacement sensor 2 according to the present embodiment is a pencil-type displacement sensor, and one end portion is a movable portion 3 having a contact 4 formed at the tip. In the contact displacement sensor 2, a detection signal corresponding to the position of the movable part 3 in the axial direction is generated. The contact-type displacement sensor 2 and the controller 7 are electrically connected by a cable 6, and an AC power supply for driving is supplied from the controller 7 to the displacement sensor 2, and a detection signal generated by the displacement sensor 2 is received. It is transmitted to the controller 7. An indicator lamp is provided at the other end of the contact displacement sensor 2, and a cable 6 is connected to the indicator lamp case 5.

  For example, when measuring a height difference such as unevenness on a substrate surface due to a semiconductor element as the measurement target A, the contact-type displacement sensor 2 is arranged perpendicularly to the substrate surface with the contact 4 in contact with the substrate surface. The At this time, when the displacement sensor 2 is moved along the substrate surface, the movable portion 3 expands and contracts in the axial direction according to the height difference of the substrate surface. The amount of displacement due to this height difference is output as a detection signal.

  The controller 7 is provided with a display unit 8, a power switch 9, and a reset switch 10, and a displacement amount from the reset time is displayed on the display unit 8 in real time.

  FIG. 2 is a diagram showing an example of the details of the main part of the displacement measuring device of FIG. 1, and shows a cross-sectional state of the contact-type displacement sensor 2 connected to the cable 6. The contact-type displacement sensor 2 includes a mounting portion 24 for attaching the indicator lamp case 5, a bobbin 13 for mounting the exciting coil 12, a movable portion including a core holder portion 15, a shaft portion 17 and a connecting portion 18, and a movable portion. The coil-shaped spring 11 for urging in the axial direction, the bearing portion 20 for holding the shaft portion 17 so as to be slidable, and a cylindrical housing 23 are configured.

  The mounting portion 24 is a cylindrical member made of resin, and an engagement hole for mounting the indicator lamp case 5 is provided on the end surface. Further, the attachment portion 24 is adapted to engage with one end of the housing 23.

  The bobbin 13 is a cylindrical winding holding member made of an insulating resin. For example, two independent exciting coils 12 are mounted coaxially. In the bobbin 13, a hollow portion for inserting a core (magnetic core) is formed in the axial direction. A detection signal corresponding to the position in the hollow portion of the core is generated by the exciting coil. The bobbin 13 and the attachment portion 24 are attached to the housing 23 from one end side of the housing 23 together with the cylindrical shield member 22 and the insulating member. The attachment portion 24 and the bobbin 13 may be integrally formed.

  The core holder portion 15 is a resin-made holding member that holds the core in parallel to the axial direction, and can enter the hollow portion. The core is made of a magnetic material such as an amorphous alloy or iron, and is mounted in the core holding tube 14 at the tip of the core holder portion 15. That is, the core holding portion in the core holding tube 14 is a core forming portion in the movable portion. The core holding tube 14 is made of metal. The core holder portion 15 is provided with a spring receiving portion 16 that comes into contact with the tip of the spring 11. The diameter of the spring receiving portion 16 is the same as the outer diameter of the spring 11. The core holder portion 15 may be entirely made of metal.

  The shaft portion 17 is a rod-shaped metal member provided with a contact 4 at the tip. The connection part 18 is a connection member which connects the core holder part 15 and the shaft part 17 so that bending is possible. The connecting portion 18 operates as a joint that suppresses excessive force applied to each portion when the movable portion is incorporated into the bobbin 13 from the other end side of the housing 23. Here, it is assumed that the connecting portion 18 is one independent member made of an insulating resin, and either or both of the shaft portion 17 and the core holder portion 15 are connected to the connecting portion 18 via an elastic adhesive member. Shall be connected. Specifically, an insulating collar having a H-shaped cut surface by a plane parallel to the axial direction can be used.

  The bearing portion 20 includes a ball bearing 21 and a bearing holder, and holds the shaft portion 17 parallel to the axial direction. The bearing unit 20 is attached to the other end of the housing 23. The stopper 19 pinned to the shaft portion 17 contacts the inside of the bearing portion 20 to prevent the movable portion from jumping out of the bearing portion 20 beyond a predetermined movable range.

  A bellows-like dust boot 25 is provided at a portion of the shaft portion 17 that protrudes in the axial direction from the bearing portion 20 to prevent water, dust, and the like from entering the housing 23.

  The spring 11 is disposed coaxially with the core holding tube 14 and is entirely accommodated in the hollow portion. That is, the spring 11 is always in the hollow portion from the state in which the core holder portion 15 is pushed into the hollow portion and the spring 11 is most contracted to the state in which the spring is extended and the stopper 19 is in contact with the bearing portion 20. The bobbin 13 is not exposed to the outside. Thereby, it is possible to prevent the spring 11 from meandering outside the bobbin 13. Therefore, the core of the movable part can be pushed into the hollow part without the spring 11 interfering with the bobbin 13. That is, the core can be pushed into the hollow portion without causing contact with wear or hooking noise. Moreover, since the whole spring 11 is accommodated in the bobbin 13, interference with the spring 11 and the bobbin 13 can be prevented effectively, without increasing the full length of a sensor main body.

  The spring 11 is formed so that the difference between the diameter of the hollow portion and the outer diameter of the spring 11 is smaller than the difference between the inner diameter of the spring 11 and the diameter of the core holding tube 14. That is, the interval between the wall surface of the hollow portion and the outer peripheral surface of the spring 11 is smaller than the interval between the inner peripheral surface of the spring 11 and the peripheral surface of the core holding tube 14. Here, the diameter (outer diameter) of the spring 11 is substantially the same as the diameter of the hollow portion. Thereby, since the hollow part wall surface can be used as a guide when the spring 11 expands and contracts, the spring 11 can be prevented from meandering or buckling in the hollow part. In particular, the meandering and buckling of the spring 11 in the hollow portion ahead of the tip of the core holding tube 14 is prevented. Therefore, when the movable portion is pushed in, the spring 11 pushes the core holding tube 14 in a direction perpendicular to the axial direction (lateral direction). (Direction) force can be effectively prevented.

  FIGS. 3A and 3B are cross-sectional views showing an operation example of the contact displacement sensor of FIG. 2. FIG. 3A shows a state in which the movable portion is pushed out from the bobbin 13 by the spring 11. FIG. 3B shows a state in which the movable part is pushed into the bobbin 13. In a state where the movable part is pushed out from the bobbin 13 by the spring 11, the spring receiving part 16 is positioned near the entrance of the hollow part. At this time, the position of the core is one excitation coil side, that is, the entrance side of the hollow portion. On the other hand, when the movable part is pushed into the bobbin 13, the spring receiving part 16 enters the center of the hollow part. At this time, the position of the core is the other exciting coil side, that is, the side opposite to the entrance of the hollow portion.

  In general, the outer diameter of a coiled spring swells when it is compressed in the axial direction. Considering this, the outer diameter of the spring 11 at the time of extension is formed to be smaller than the diameter of the hollow portion. Specifically, when the diameter of the hollow portion is 5 mm, the outer diameter in the natural length of the spring 11 is 4.8 mm. In this case, even if meandering occurs in the spring 11, it can be within 5−4.8 = 0.2 mm.

  In general, the inductance of each exciting coil 12 varies depending on the position of the core in the hollow portion. Utilizing this fact, a detection signal corresponding to the position of the core in the hollow portion is generated. For example, each excitation coil 12 is supplied with alternating phase alternating current, and the core position is detected from the amplitude and phase of the generated signal.

FIG. 4 is a circuit diagram showing an example of the details of the main part of the contact-type displacement sensor of FIG. 2, in which a differential transformer including an exciting coil 12 and a core is shown. Inductance L ₁ and L ₂ of the exciting coils 12 is changed according to the axial position of the core within the hollow portion. When alternating-phase alternating current is supplied to the terminals B and D, a signal corresponding to the inductance ratio is generated at the terminal C. The position of the core can be determined from the amplitude and phase of this signal.

  FIG. 5 is an exploded view of the main part of the contact displacement sensor of FIG. The bobbin 13 and the spring 11 are mounted in the housing 23 from one end side of the housing 23. On the other hand, the movable portion in which the shaft portion 17 is inserted into the bearing portion 20 is mounted in the housing 23 from the other end side of the housing 23. The bearing unit 20 is fixed to the end of the housing 23. An O-ring 31 made of an elastic member such as rubber is provided on the bearing 20 side of the stopper 19 in order to reduce an impact when the stopper 19 comes into contact with the bearing 20.

  FIG. 6 is a cross-sectional view showing the details of the main part of the contact-type displacement sensor of FIG. 2, and shows the state of the connecting portion 18 that connects the core holder portion 15 and the shaft portion 17 so that they can be bent. The core holder part 15 and the shaft part 17 are connected by a connecting part 18 so that they can be bent.

  In particular, the shaft portion 17 is bonded to the connecting portion 18 made of an insulating collar using an elastic adhesive 32. Thereby, it is possible to prevent an excessive force from being applied to each part during assembly of the sensor body. That is, the assembly error that occurs when the bearing portion 20 or the like is incorporated into the housing 23 can be absorbed by the connecting portion 18, so that the distal end portion of the core holder portion 15, in particular, the spring receiving portion 16 can be Interference with the wall surface can be effectively suppressed.

  Specifically, when the inner diameter of the connecting portion (insulating collar) 18 is 4.5 mm, the diameter of the shaft portion 17 is 4.0 mm, and the connecting portion 18 is 4.5-4.0 = 0. Can absorb lateral displacement of about 5 mm. That is, the connecting portion 18 operates as a joint that suppresses excessive force applied to the shaft portion 17 and the spring receiving portion 16 when the movable portion is incorporated into the bobbin 13 from the other end side of the housing 23. Thereby, since the required assembly precision can be reduced, the assembly of the sensor body is facilitated.

  According to the present embodiment, since the spring 11 can be prevented from meandering outside the bobbin 13, the core of the movable part can be pushed into the hollow part without the spring 11 interfering with the bobbin 13. Moreover, since the whole spring 11 is accommodated in the bobbin 13, the interference of the spring 11 and the bobbin 13 can be prevented without increasing the total length of the sensor body.

  Further, since it is possible to prevent a lateral force from being applied to the core due to the meandering of the spring 11, it is possible to suppress variation in the detection value of the displacement amount.

  In the present embodiment, an example in which the core holder portion 15 and the shaft portion 17 are connected via the elastic adhesive 32 has been described. However, the present invention is not limited to this and is connected so as to be foldable. Other connecting means may be used as long as they are suitable. For example, the connecting member itself such as an insulating collar may be elastic. Moreover, you may be comprised mechanically like a universal joint.

It is the external appearance perspective view which showed an example of the displacement measuring device containing the contact-type displacement sensor by Embodiment 1 of this invention. It is the figure which showed an example of the principal part detail in the displacement measuring device of FIG. It is sectional drawing which showed the operation example in the contact-type displacement sensor of FIG. FIG. 3 is a circuit diagram illustrating an example of details of a main part of the contact-type displacement sensor of FIG. 2, in which a differential transformer including an exciting coil 12 and a core is illustrated. It is the figure which decomposed | disassembled and showed the principal part detail in the contact-type displacement sensor of FIG. It is sectional drawing which showed the principal part detail in the contact-type displacement sensor of FIG. 2, and the mode of the connection part 18 which connects the core holder part 15 and the shaft part 17 so that bending is possible is shown. It is the top view which showed the external appearance of the conventional contact-type displacement sensor. It is the figure which showed the detail of the principal part in the contact-type displacement sensor of FIG. It is the figure which showed the principal part detail in the contact-type displacement sensor. It is the figure which showed the principal part detail in the contact-type displacement sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Displacement measuring device 2 Contact-type displacement sensor 3 Movable part 4 Contact 5 Indicator lamp case 6 Cable 7 Controller 8 Display part 9 Power switch 10 Reset switch 11 Spring 12 Excitation coil 13 Bobbin 14 Core holding tube 15 Core holder part 16 Spring receiving part 17 Shaft portion 18 Connecting portion 19 Stopper 20 Bearing portion 21 Ball bearing 22 Shield member 23 Housing 24 Mounting portion 25 Dust boot 31 O-ring 32 Elastic adhesive

Claims (7)

An exciting coil for generating a detection signal;
A bobbin equipped with the exciting coil and having a hollow portion formed in the axial direction;
A movable part in which a core inserted into the hollow part is formed at one end, and a contact is formed at the other end protruding in the axial direction from the bobbin;
A contact-type displacement sensor, comprising: a coiled spring that is arranged coaxially with the movable part and is always housed in the hollow part and biases the movable part in the axial direction.   The contact displacement sensor according to claim 1, wherein the spring has a diameter substantially the same as a diameter of the hollow portion.   2. The spring according to claim 1, wherein the difference between the diameter of the hollow portion and the outer diameter of the spring is smaller than the difference between the inner diameter of the spring and the diameter of the core forming portion in the movable portion. Contact displacement sensor as described in 1. The movable part holds the core and a core holder part that contacts the tip of the spring;
A shaft portion provided with the contact;
The contact-type displacement sensor according to claim 1, comprising a connecting part that connects the core holder part and the shaft part so as to be bendable.   The contact displacement sensor according to claim 4, wherein the connecting portion is connected through an adhesive member having elasticity.   The contact displacement sensor according to claim 4, wherein the connecting portion is an insulating collar made of an elastic member. A cylindrical housing on which the bobbin is mounted;
The contact-type displacement sensor according to claim 4, further comprising a bearing formed in the housing and slidably holding the shaft portion.

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