JP3977366B2 - X-ray foreign object detection device - Google Patents

Description

  The present invention relates to an X-ray foreign matter detection device that detects foreign matter in an inspection object using X-rays, in particular, a shell in an inspection object that is conveyed in a tubular conveyance path such as a fluid food, The present invention relates to an X-ray foreign matter detection apparatus suitable for detecting bone pieces, metal pieces and other foreign matters.

  An X-ray foreign object detection apparatus using X-rays includes an inspection object such as fluid food or an inspection object mixed with a transport fluid such as water (for example, a mass ratio of 1/5 to 5). 1/7, the shell strip mixed with water) is transported by a conduit along a predetermined transport route, and the inspected object in the transport route is irradiated with X-rays to determine the distribution of transmitted X-ray dose at that time. There is one that grasps and detects the presence of a foreign substance from the transmitted X-ray dose distribution state.

As a conventional X-ray foreign substance detection apparatus of this type, for example, as described in Patent Document 1, a one-dimensional multi-channel X-ray sensor composed of a plurality of X-ray detection elements is arranged so as to be substantially orthogonal to the conveyance path. In some cases, the detection signal of each channel of the X-ray sensor during the continuous conveyance of the inspection object is compared with a threshold value for detecting a foreign object to detect the presence of the foreign object with a required resolution. Further, in this apparatus, when a foreign object detection signal is output, the discharge valve is operated, and the inspection object including the foreign object is discharged to the outside through the discharge valve.
Japanese Patent No. 2591171

  However, in the X-ray foreign matter detection apparatus as described above, when the inspection object including the foreign object is discharged from the transfer path through the discharge valve to the outside, both the inspection object including the foreign object and the inspection object before and behind the transfer object are transported. However, since there are fluctuations in the flow rate of the test object due to fluctuations in the density or mixing ratio of the test objects, fluctuations in the liquid level of the supply tank, etc. It was necessary to set the conveyance delay time short and the discharge time long.

  Therefore, there is a problem that the quantity of non-defective products before and after being discharged out of the system together with the foreign matter increases, and the production efficiency of the product to be inspected is reduced due to the waste. .

  The present invention has been made to solve such a problem of the prior art, and an X-ray foreign matter detection apparatus capable of minimizing the discharge amount of an inspection object discharged to the outside from a conveyance system due to foreign matter contamination. The purpose is to provide.

To achieve the above object, the present invention provides (1) X-ray irradiation means for irradiating X-rays to a fluid inspection object or an inspection object mixed with a fluid conveyed in a tubular conveyance path, X-ray detection means for detecting X-rays that are irradiated from the X-ray irradiation means to the inspection object and transmitted through the inspection object, and the inspection object based on the transmitted X-ray dose detected by the X-ray detection means Determining means for determining whether or not the sample contains a foreign substance, discharge means capable of discharging the inspection object from a predetermined discharge position of the conveyance path to the outside of the conveyance path, and the inspection means by the determination means In the X-ray foreign object detection apparatus, comprising: a discharge control means for outputting a discharge command signal for instructing a discharge operation of the discharge means based on the determination result when it is determined that the object contains a foreign object. of road, before a upstream side of the predetermined discharge position Wherein providing the flow rate measuring means for measuring the flow rate of the subject transferred to the conveying path between a position for detecting the X-rays transmitted through the inspected object to the predetermined discharge position by the X-ray detecting means, Based on the discharge time including the measurement information of the flow velocity measuring unit and the switching operation time of the discharge unit, the discharge control unit discharges the inspection object including the foreign matter out of the conveyance path by the discharge unit. In addition, during the switching operation of the discharge means, the inspection object including the foreign matter is discharged out of the conveyance path by the discharge means based on the flow rate measurement information about the inspection object immediately before the switching operation. It is characterized by controlling the timing .

With this configuration, when a foreign object is detected, the movement state of the inspection object including the foreign object in the transport path can be grasped based on the flow velocity of the inspection object, and the arrival time of the foreign object at the discharge position is reached. Correspondingly, the operation of the discharge means can be controlled, and the discharge amount of the inspection object can be suppressed to the minimum amount with little waste. Further, since the discharge timing is controlled based on the discharge time including the switching operation time of the discharge means, it is possible to set an appropriate discharge timing with less waste.

Further, the flow rate of the inspection object including the foreign object is accurately measured on the discharge means side from the detection position of the foreign object, and the movement state of the inspection object from the detection position of the foreign object to the discharge position by the discharge means is more accurately grasped. The foreign matter can be reliably discharged while suppressing the discharge amount to a minimum amount.
Furthermore, even when the discharge means temporarily becomes a small opening or a blocked state between the discharge operation and the normal operation, the timing at which the discharge command signal is turned off is determined based on the time when the subsequent foreign object is detected. Even when the flow velocity measurement information cannot be temporarily captured for the inspection object including the subsequent foreign matter, the discharge operation time can be extended by that amount using the flow velocity measurement information of the immediately previous inspection object.

In the present invention, (2) when the discharge means is constituted by a valve type sorter whose opening is reduced during the switching operation, in particular, (3) the discharge means is It is switched between a discharge operation position for performing a discharge operation and a normal operation position for allowing the inspection object to pass downstream of the transport path, and is in a closed state during the switching operation between the discharge operation position and the normal operation position. This is preferable.
In the X-ray foreign object detection device of the present invention, (4) the flow velocity measuring means may measure the flow velocity of the inspection object in the conveyance path in a non-contact manner. With this configuration, there is no possibility of adversely affecting an object to be inspected such as food, and the maintainability is improved.

According to the present invention, when a foreign object is detected, based on the flow rate of the inspection object, the movement state of the inspection object including the foreign object in the conveyance path is grasped, and the arrival time of the foreign object is reached correspondingly The operation of the discharge means can be controlled, and the discharge amount of the inspection object can be suppressed to the minimum amount with little waste. As a result, it is possible to prevent the non-defective products before and after the object to be inspected including foreign matters from being wasted. Furthermore, since the discharge timing is controlled based on the discharge time including the switching operation time of the discharge means, it is possible to set an appropriate discharge timing with less waste. In addition, the movement state of the object to be inspected from the foreign object detection position to the discharge position by the discharge means can be grasped more accurately, and the discharge amount per time can be suppressed to the minimum amount. Even if it becomes temporarily small or becomes a block state, an appropriate discharge timing can be determined.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First embodiment]
1 to 4 are diagrams showing a schematic configuration of the X-ray foreign object detection device according to the first embodiment of the present invention.

  First, the configuration will be described.

  In FIG. 1, a pipe 11 constituting a tubular conveyance path inside has a predetermined flow velocity and a conveyance direction (indicated by an arrow Q in the figure) of an inspection object (not shown) that can flow from the left side in the figure. For example, ingredients such as retort foods, fluid or extensible foods such as fish surimi, and foods such as shellfish shells are used as water to be inspected. Or the like contained in a transfer fluid such as a predetermined dilution rate is transferred through the pipe 11. In addition, although the dilution rate here is a capacity | capacitance ratio, either the ratio converted into the capacity | capacitance from mass, or the mass ratio itself is used.

  In the vicinity of the pipe 11, an X-ray irradiation unit 12 (X-ray irradiation means) for irradiating the inspection object passing through the pipe 11 and the inspection object irradiated from the X-ray irradiation unit 12 to the inspection object. And an X-ray detector 13 for detecting X-rays transmitted through the pipe 11 are disposed opposite to each other with the pipe 11 interposed therebetween.

  The X-ray irradiation unit 12 and the X-ray detection unit 13 are well-known, but the X-ray irradiation unit 12 collides, for example, thermoelectrons from the cathode filament with the anode target by a high voltage between the cathode and the anode. And is a cylindrical X-ray tube that generates X-rays, and is provided such that its longitudinal direction is orthogonal to the transport direction. Then, X-rays are irradiated toward the lower X-ray detection unit 13 in a substantially triangular screen shape through a slit (not shown) along the longitudinal direction. The X-ray detection unit 13 is an X-ray line sensor camera that performs X-ray detection at a predetermined resolution by arranging a plurality of X-ray detection elements in parallel in the radial direction of the pipe 11, for example. A detection signal is output.

  An X-ray irradiation region by the X-ray irradiation unit 12 in the transport path formed by the pipe 11, that is, a predetermined distance L1 from the X-ray detection position to the object to be inspected in the transport direction downstream from the X-ray detection position in the transport direction. There is provided a valve type sorter 14 (discharge means) that can perform an operation of discharging the pipe 11 from a predetermined discharge position to the outside of the conveyance path (hereinafter referred to as a discharge operation).

  As shown in FIGS. 2 and 3, this valve type sorter 14 is composed of, for example, a pneumatic rotation actuator 14a and a three-way ball valve 14b driven thereby, and the inside is not shown in detail. Non-defective conveyance that communicates the conveyance path on the inspection area side in the pipe 11 with the conveyance path in the non-defective discharge pipe portion 11c downstream from the valve type sorter 14 when the valve body having a letter-shaped passage is in the normal operation position. When the path and the valve body are switched to rotate from the normal operation position to the discharge operation position, the inspection area side transfer path in the pipe 11 is communicated with the transfer path in the NG discharge pipe portion 11d to the outside. It has a foreign substance-contaminated product conveyance path that discharges and opens. In the present embodiment, the predetermined discharge position corresponds to the center position of the ball valve body, and the discharge flow path length L2 of the valve type sorter 14 from the predetermined discharge position is the radius of the ball valve body.

  The switching control of the valve type sorter 14 is executed by the control circuit 30.

  Based on the X-ray detection signal from the X-ray detection unit 13 (the transmitted X-ray dose that has passed through the inspection object in each area of the inspection region), the control circuit 30 has a sufficient moving distance due to the transfer of the object to be transferred. A determination unit 31 that outputs a foreign object detection signal when it is determined whether or not the object to be inspected includes a foreign object, and the object to be inspected including the foreign object is moved out of the conveyance path. A discharge timing control unit 32 (discharge timing control means) that determines the start timing and holding time of the discharge operation of the valve type sorter 14 to discharge and outputs a discharge command signal corresponding thereto, and discharge from the discharge timing control unit 32 A command signal is input to drive the pneumatic rotation actuator 14a of the valve type sorter 14, and the three-way ball valve 14b of the valve type sorter 14 is set to any one of the normal operation position and the discharge operation position. And a drive circuit section 33 for one to hold the switching or its position in or.

  The determination unit 31 takes in the X-ray detection signal of the X-ray detection unit 13 and performs image processing for drawing a predetermined transmitted X-ray dose distribution, and threshold determination of the transmitted X-ray dose transmitted through the inspection object in each area of the inspection region Etc. is executed, and it is determined whether or not a foreign object is contained in the inspection object according to the processing result.

  The determination unit 31 and the discharge timing control unit 32 are not shown in a specific hardware configuration. For example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an input / output interface circuit (Hereinafter, referred to as an I / F circuit), and the drive circuit unit 33 includes, for example, a solenoid valve for air switching, a programmable controller, and the like.

  On the other hand, between the inspection area, that is, the X-ray detection position in the transport path in the pipe 11 and the predetermined discharge position, the flow velocity of the inspection object transported in the pipe 11 (including that obtained from the flow rate). Is provided for each predetermined time. A flow velocity measuring unit 21 (flow velocity measuring means) is provided. Here, the predetermined time is, for example, a short time that is the same as the detection time of the detection signal of the X-ray detection unit 13, but the flow rate is not measured while the operation position of the valve type sorter 14 is switched (details will be described later).

  The flow velocity measuring unit 21 is, for example, a non-contact type flow meter such as an ultrasonic type, an optical type, or an electromagnetic type that does not have a measuring unit inside the pipe 11 and is installed at or near the outer periphery of the pipe 11.

  When the discharge timing control unit 32 receives the foreign object detection signal from the determination unit 31, the discharge timing control unit 32 determines whether or not the X-ray detection position is based on the determination result output and the flow velocity measurement information of the flow velocity measurement unit 21 at the time when the determination result is output. Delay time (transport distance L1 / flow velocity V−switching time to discharge operation position) and time required for discharge (discharge flow path length L2 / flow velocity V + switching time to normal operation position side) based on transport to a predetermined discharge position, etc. The discharge command signal is output for a discharge time T1 that defines the discharge amount of the inspection object including foreign matters (hereinafter referred to as NG discharge amount) at a timing in consideration of the above.

  The NG discharge amount at this time is the cross-sectional area S × flow velocity V × discharge time T1 of the conveyance path. More specifically, as shown in FIG. 4, the valve type sorter 14 is discharged from the normal operation position. A first switching time ta for switching to the position, a discharge holding time tb for which the valve type sorter 14 is held at the discharge operation position, and a second switching time for the valve type sorter 14 to return from the discharge operation position to the normal operation position. In consideration of tc, for example, a time (ta / 2 + tc / 2 + tb) obtained by adding a half of each of the first switching time ta and the second switching time tc and the discharge holding time tb, The inspection object discharge time T1 is set. Here, the first and second switching times ta and tc are each halved is a process for calculating a substantial NG emission amount at the time of opening and closing the valve. Needless to say, the calculation conditions can be appropriately set according to the above. Further, such setting, and further setting of the dilution rate, conveyance speed (flow velocity), and the like can be manually input from the input unit 15.

  When an object to be inspected with foreign matter passes through the inspection area and is judged to be foreign matter, a little processing time (for example, about several tens to several hundred milliseconds) has passed since the passage time, so valve type selection The machine 14 uses the elapsed time Tf (≈conveyance distance L1 / flow velocity V) required to convey the inspection object (foreign matter) from the rising point of the foreign matter detection signal as the determination result output to the predetermined discharge position as a reference. The discharge operation position is switched from the time point to a predetermined time (for example, te / 2) before the error time te, and after the discharge time T1, the normal operation position is restored. On the other hand, when a non-defective inspection object that does not contain foreign matter passes through the inspection region, the valve type sorter 14 is switched to the normal operation position unless foreign matter is mixed in the inspection object.

  2 and 3, the object to be inspected is pumped out of the product receiving box 41 by the pump 42 driven by the motor 42a and discharged into the pipe 11, so that the cross-sectional area of the conveying path is larger than that of the front and rear. It passes through the X-ray inspection section 11a of the narrowed pipe 11 and is transported further downstream, and depending on whether foreign matter is mixed in or not, the valve type sorter 14 determines whether the non-defective discharge pipe section 11c or NG discharge pipe section 11d of the pipe 11 Distributed to one of them. In addition, when the valve type sorter 14 discharges the NG product to be inspected containing foreign matter to the outside of the pipe 11, the control circuit 30 displays the operation state on the screen 16 in a predetermined display format, print output, etc. Direct output or information output (indirect output) to an external display or printer.

  On the other hand, the X-ray inspection unit 11a of the pipe 11 that substantially coincides with the inspection region of the inspection object by the X-ray irradiation unit 12 and the X-ray detection unit 13 moves a part of the pipe 11 made of plastic, for example, up and down within its elastic range. As shown in FIG. 2, the cross-sectional area is gradually changed in a predetermined conveyance section before and after the X-ray inspection unit 11a, and is flattened so as to have a substantially oval cross section with the minimum cross-sectional area in the inspection area. Thus, the height of the inspection area is made constant. The inspection object being transported has a flow rate Q = channel cross-sectional area S × flow velocity V substantially constant at each transport position in accordance with a change in the transport path cross-sectional area in the pipe 11. The flow velocity is increased in the vicinity, but then gradually decelerated to return to the speed before reaching the outside of the predetermined conveying section. In addition, the X-ray inspection part 11a of the pipe 11 can change the pressure height from the upper and lower sides so as to change the flatness, and can variably set the conveyance path cross-sectional area inside thereof. Moreover, if it is a specification which does not variably set a conveyance path cross-sectional area, it is not necessary to elastically deform the X-ray inspection part 11a of the pipe 11. The flow velocity measuring unit 21 is located between the X-ray inspection unit 11a and the valve type sorter 14 at a position where there is no change in the pipe cross-sectional area outside the predetermined conveying section, and the flow velocity of the pipe cross-sectional area is substantially uniform and the valve type. Upstream by a predetermined amount from the sorter 14 (upstream from the range susceptible to the shape of the valve body passageway (T-shape) of the valve-type sorter 14 when in communication with the non-defective product conveyance path or the foreign substance conveyance path. Is arranged. The installation position is such that the object to be detected actually flows into the pipe 11 or is provided in the upstream passage portion 11b of the X-ray inspection unit 11a at the time of installation or maintenance when the operating conditions of the X-ray foreign object detection device are determined. It is set to an optimal installation position where the amount of NG discharge can be minimized within a range where no misselection occurs by introducing a foreign material sample from an unshown open / close type sample inlet.

  Next, the operation will be described.

  In the X-ray foreign matter detection apparatus of the present embodiment configured as described above, the inspection object is pumped out of the product receiving box 41 by the pump 42 and discharged into the pipe 11, and the X-ray inspection unit 11 a of the pipe 11. After passing through the front and rear cross-sectional area change sections and transported further downstream, the flow velocity is measured by the flow velocity measuring unit 21 when the velocity reaches a stable speed.

  Further, the X-ray irradiation unit 12 uniformly irradiates the inspection object in the inspection region with X-rays, and the transmitted X-ray dose from the inspection object is a line sensor in each area in the width direction of the inspection region. 13, predetermined image processing is executed by the image processing circuit of the determination unit 31 in the control circuit 30 based on the detection signal of the predetermined number of bits, and the presence or absence of foreign matter is determined.

  Then, according to the determination result, the pneumatic actuator of the valve type sorter 14 is driven, and the inspection object free from foreign matter is carried out from the non-defective product discharge pipe portion 11c of the pipe 11 to the non-defective product receiving box 43 and mixed with foreign matter. The inspected object is distributed and discharged from the NG discharge pipe portion 11d to the outside of the transport system.

  In this embodiment, when the determination result of the determination unit 31 is that foreign matter is mixed and a foreign object detection signal is output from the determination unit 31, the discharge timing control unit 32 determines the flow rate measurement information of the inspection object. Then, the flow velocity of the inspection object including the foreign substance in the conveyance path is grasped, and the arrival timing to the discharge position is calculated from the conveyance time Tf to the foreign substance discharge position. As shown in FIG. From the point of time before the transfer time Tf elapses from the time of output, it is possible to reliably discharge foreign matter, and the minimum amount of NG discharge is reduced to the cross-sectional area S × flow velocity V × discharge operation time T1 of the transfer path. The discharge command signal is output during the discharge operation time T1. Therefore, the valve type sorter 14 in the normal operation position starts to be switched to the discharge operation position side from the time when the discharge command signal rises, and is opened after the first switching time ta, and the discharge holding time tb. Is held at the discharge operation position, and is returned from the discharge operation position to the normal operation position from the time when the discharge command signal is turned OFF after the discharge operation time T1 (= first switching time ta + discharge hold time tb). First, when the second switching time tc elapses, the valve is opened at the normal operation position. Although depending on the actuator of the valve type sorter 14, when the NG discharge amount is minimized, the times ta and tc required for valve switching are relatively large, and the holding time tb is often shorter than that. The total discharge time T1 can be suppressed within about several hundred milliseconds.

  As described above, in the present embodiment, the minimum discharge amount that enables reliable foreign matter discharge is variably controlled by the control of the discharge operation time T1, so that the NG discharge amount of the inspection object can be suppressed to the minimum amount with little waste. it can. In addition, the flow velocity measuring unit 21 is between the X-ray detection position where the X-ray detection unit 13 detects X-rays that have passed through the inspection object in the conveyance path and a predetermined discharge position by the valve type sorter 14. Since it is arranged, the flow rate of the inspection object including the foreign object can be accurately measured on the valve type sorter 14 side from the foreign object detection position, and the movement state of the inspection object from the foreign object detection position to the discharge position can be more Accurately grasping the foreign matter can be surely discharged while suppressing the amount of NG discharged at one time to the minimum amount.

  Furthermore, since the flow velocity measuring unit 21 detects the flow velocity of the inspection object in the conveyance path in a non-contact manner, there is no possibility of adversely affecting the inspection object such as food, and the maintenance performance of the X-ray foreign matter detection apparatus is improved. can do.

  In the above-described embodiment, the opening degree of the valve type sorter 14 decreases during the first switching time ta and the second switching time tc (the valve type sorter is intermediate between the discharge operation position and the normal operation position). Therefore, the flow velocity measurement information from the flow velocity measurement unit 21 to the discharge timing control unit 32 is not taken in during that time. However, the foreign object detection is always continued, and when a foreign object detection signal is output during the first switching time ta and the second switching time tc, or a subsequent foreign object is detected within the current transport time Tf. In such a case, the timing at which the discharge command signal is turned OFF is determined with reference to the foreign object detection time. Therefore, there is a case where the discharge time T1 is extended, and in this case, when the flow velocity measurement information cannot be taken in for the inspection object including the subsequent foreign matter, the holding time tb is used using the flow velocity measurement information for the immediately previous inspection object. Is extended, and the discharge operation time T1 is extended accordingly.

As described above, according to the present invention, when a foreign object is detected, the movement state of the inspection object including the foreign object in the transport path is grasped based on the flow velocity of the inspection object, and the arrival timing of the foreign object to the discharge position is detected. The operation of the discharge means can be controlled in response to the above, the discharge amount of the inspection object can be suppressed to the minimum amount with little waste, and the discharge timing is controlled based on the discharge time including the switching operation time of the discharge means As a result, it is possible to achieve an appropriate discharge timing with less waste , and the foreign matter in the fluid inspected object (including the extensible one) is transported (flow path). It is useful for all X-ray foreign matter detection devices that detect X-rays.

It is a block diagram which shows schematic structure of the X-ray foreign material detection apparatus which concerns on the 1st Embodiment of this invention. 1 is a front view showing an overall schematic configuration of a foreign matter inspection system including an X-ray foreign matter detection device according to a first embodiment of the present invention. 1 is a plan view showing an overall schematic configuration of a foreign substance inspection system including an X-ray foreign substance detection apparatus according to a first embodiment of the present invention. It is a timing chart which shows the setting conditions of the operation timing from the foreign material to discharge | emission operation | movement of the X-ray foreign material detection apparatus which concerns on the 1st Embodiment of this invention.

Explanation of symbols

11 Pipe (conveyance path)
11a X-ray inspection section 11c Non-defective discharge pipe section 11d NG discharge pipe section 12 X-ray irradiation section (X-ray irradiation means)
13 X-ray detector (X-ray detector)
14 Valve type sorter (discharge means)
14a Pneumatic rotation actuator 14b Three-way ball valve 15 Input unit 16 Display / recording output unit 21 Flow velocity measuring unit (flow velocity measuring means)
30 control circuit 31 determination unit (determination means)
32 discharge timing control unit (discharge control means)
33 Drive circuit section

Claims (4)

X-ray irradiating means (12) for irradiating X-rays to a fluid inspection object conveyed through a tubular conveyance path (11) or an inspection object mixed with a fluid;
X-ray detection means (13) for detecting X-rays which are irradiated from the X-ray irradiation means onto the inspection object and transmitted through the inspection object;
A determination means (31) for determining whether or not the object to be inspected contains foreign matter based on the transmitted X-ray dose detected by the X-ray detection means;
A discharge means (14) capable of a discharge operation for discharging the inspection object from a predetermined discharge position of the transfer path to the outside of the transfer path;
A discharge control means (32) for outputting a discharge command signal for instructing a discharge operation of the discharge means based on the determination result when the determination means determines that the object to be inspected contains a foreign substance. In the X-ray foreign object detection device,
Transporting in the transport path between the transport path between the position upstream of the predetermined discharge position and detecting the X-rays transmitted through the inspection object by the X-ray detection means and the predetermined discharge position Provided with a flow velocity measuring means (21) for measuring the flow velocity of the object to be inspected,
Based on the discharge time including the measurement information of the flow velocity measuring unit and the switching operation time of the discharge unit, the discharge control unit discharges the inspection object including the foreign matter out of the conveyance path by the discharge unit. In addition, during the switching operation of the discharge means, the inspection object including the foreign matter is discharged out of the conveyance path by the discharge means based on the flow rate measurement information about the inspection object immediately before the switching operation. An X-ray foreign matter detection apparatus characterized by controlling timing . The X-ray foreign object detection device according to claim 1, wherein the discharging unit is configured by a valve type sorter whose opening degree is reduced during the switching operation. The discharge means is switched by the switching operation between a discharge operation position for performing the discharge operation and a normal operation position for passing the inspection object to the downstream side of the transport path, and the discharge operation position and the normal operation. The X-ray foreign object detection device according to claim 2, wherein the X-ray foreign object detection device is in a closed state during a switching operation between positions.   The X-ray foreign object detection device according to claim 1, wherein the flow velocity measuring unit measures the flow velocity of the inspection object in the conveyance path in a non-contact manner.

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