DE102014200004A1 - Motor-driven gate with a safety device - Google Patents

Abstract

The motorized door has a safety device (20), a motor control (22), a movable door leaf (30) and a blanking device. The safety device (20) detects a foreign object (46) which is located in a free part (40) of the movement area (34) below a door edge (32) and prevents a collision. The safety device (20) has a light grid with a large number of channels, each channel being at least partially in the range of motion. The blanking device prevents the light curtain from evaluating the closing door leaf (30), which gradually passes over the individual channels, as a foreign object. The blanking device is normally inactive. It is only activated when there is a closing command for the door leaf (30) in the motor control (22) and at least one of the following features is fulfilled: a) the safety device (20) has been successfully tested, b) it is active a driving signal.

Description

The invention relates to a motor-driven gate according to the preamble of patent claim 1.

Such a gate is from the EP 2 374 985 A1 known. The disclosure of this patent application belongs fully to the disclosure content of the present application.

Out EP 902 157 B1 and EP 902 158 B1 motorized gates are known. In these gates, the light grid of the safety arrangement is arranged in the door guides. The entire door opening width is monitored. The gate guides also serve the mechanical support of the individual light receiver and light transmitter. The light receivers and the light emitters are each arranged in a row. The lateral guide slots in the door guides are also monitored. In this case, that channel of the light grid, which is located in a closing movement of the door leaf immediately below the gate edge, is neither in the on state nor in the off state, but assumes an intermediate state. In this intermediate state, which is a third state, no monitoring takes place. If a foreign object interrupts this channel, no fault is detected. This can lead to consequential accidents.

The light emitters are usually arranged in one of the two door guides. Usually, the light receivers are arranged in the other door guide, but there may also be arranged reflectors, which allows the light receiver can be accommodated in the same door guide as the light emitter. The light receiver and light transmitter can also be arranged elsewhere.

The closing direction of the door leaf can be arbitrary. For example, the gate can close up. When it is spoken of a closing movement of the door leaf down or from a device located immediately below the gate edge, it is to be understood that usually the closing movement takes place downwards. If it is in a different direction, for example laterally or upwards, the corresponding terms should be used.

The blanking device is usually arranged in the safety device. It can also be arranged in the gate control. The blanking device ensures that the closing door leaf, which gradually passes over individual channels of the safety light grid during the closing process, is not evaluated as a foreign object. The blanking devices suppress the function of the safety light grid as long as they are active.

The blanking devices of the prior art have the disadvantage that they can easily be outwitted. Thus, for example, with an open, non-moving door leaf by means of an object, the individual channels in a certain way sequentially or jointly cover, resulting in that the blanking device is activated. It then remains active. However, this means that the safety device can no longer detect foreign objects. If it then comes to a closing movement of the door leaf, this can lead to serious accidents.

Overlapping the blanking device can deliberately, for example, by a targeted manipulation with an object, such as a board done. Overlapping can also be done unconsciously, for example, if the tines of a forklift protrude into channels of the light grid and are lowered or otherwise moved. This may also be an object on the tines. Then the safety device enters the blanking state, in other words the blanking device is activated, but this has not now been achieved by deliberate tricking.

Proceeding from this, the present invention seeks to further develop a motor-driven gate of the type mentioned above and to improve that outbid the blanking device is excluded as much as possible. This should be achieved with the simplest possible measures and with the least possible expenditure of additional hardware and / or software. It should as many, already existing functions, d. H. Hardware and software to be used.

This object is achieved by a motor-driven door with the features of patent claim 1.

The invention makes it possible to actively switch and hold the blanking device only when it is certain that it is the gate edge which interrupts the channels during the closing movement of the door leaf. If it is not the gate edge, but an object that is in the range of the rays of the light grid, no activation of the blanking device. If there is a blanking device, there is always some risk that it will be outsmarted. By means of the invention, the possibilities of outsmarting the blanking device are very clearly restricted and preferably virtually completely eliminated. Since the blanking device is only switched active or released when a Closing command for the door leaf is present and the safety device is tested and / or a driving signal is present, the possibilities of override are very limited. This is further improved in that preferably the blanking device is kept active only as long as there is actually a drive signal of the door leaf and / or the door leaf has not exceeded a set time limit for reaching a detectable position of the door leaf during its closing movement. Detecting takes place in the latter case by means of at least one channel of the safety device.

The invention makes it possible, despite the blanking state, for the channels, which have not yet been run over by the gate edge, to be able to detect any foreign object. They are in the same state as without blanking. The closer the blanking device and door movement are linked, the lower the possibility of outsmarting the blanking device. Advantageously, the door drive is designed so that it generates a position signal of the door leaf. Then the position of the gate edge is known exactly. In this way, the blanking can be done very precisely and a Überlistung practically completely excluded.

The driving signal can be obtained in different ways. It can be derived directly from the movement of the gate itself, for example by means of a sensor associated with the output shaft of the drive motor for the gate. Also, from the engine control, in particular the inverter, such a signal can be derived. A driving signal can also be obtained via the light grid. For this purpose, it is determined when the lower edge of the door covers the individual parallel light beams Kx successively. The gate is thus detected gradually in each case at the points where parallel channels Kx are, from which the driving signal is obtained. Previously, a learn run saves how long the gate takes to move between channels, these values are stored in a look-up table in a memory, so the movement of the door can be tracked on a later trip. There are also other, other ways to generate a driving signal.

The close command is the "Start" command issued by a user. For example, the user presses a button, operates a remote control or the like and thus triggers the door movement.

The testing of the safety device takes place according to the prior art. The testing is regulated in standards.

In this motor-driven door many advantages of the motor-driven gates of the type mentioned are obtained. The light grid can be installed directly in the door opening, namely in the side door guides. It monitors the full door width, including any lateral guide slots. There are no two light grids, one in front of and one behind the gate. There are no requirements made on the nature of the door leaf above the gate edge, d. H. the light rays can be interrupted above the gate edge or not. The area below the gate edge can be monitored with parallel beams, which allows a faster response time, or with oblique beams, in particular cross beams, which allows a finer resolution. The grid of the channels may vary within the light grid, for example, the channels in the lower region and thus in the vicinity of the closed position of the door leaf 40 mm, in the upper region 120 mm spaced from each other in the direction of actuation of the door leaf. The functionality of the door leaf is virtually unlimited, it can stop and start again during opening and closing, even if the direction is reversed, without the safety device reporting an error.

The light beam directly below the gate edge is included in the monitoring of the doorway to the end, so there is no monitoring gap at the most dangerous point.

Preferably, the position of the door is additionally detected. This can be done by means of the safety device by determining which channels the gate has already passed. The position can also be obtained via the sensor. If this z. B. is designed as a Hall sensor, the delivered pulses can be counted. If it is designed as a rotary encoder, one obtains an immediate information about the position.

The invention is not limited to conventional goals by the z. B. trucks or people can pass through limited. Gate can also be understood to mean an opening or closing disc in a motor vehicle, for example in a motor vehicle door, a sliding door or the like. The following description is always based on a lifting gate, which is not intended to be limiting. Other types of gate are included in the present application. The term door leaf is understood to mean any possible embodiment of a closure part, in particular a rigid door leaf, a sectional door, a lattice gate, a glass door, etc.

Preferably, the gate edge, viewed in the direction of movement of the door, is formed so high that it always interrupts at least two adjacent channels, which have parallel rays. Then a edge detection is possible. It takes place with three adjacent monitoring channels and parallel light beams. Parallel means transversely, in particular at right angles to the direction of movement of the door leaf. Preferably, a multiplexing method is used, so the monitoring channels are sampled serially. Parallel scanning is possible. The other channels, which are located in the free part of the range of motion below the gate edge, are monitored with parallel and / or oblique, in particular crossed, light beams. These other channels do not include the three adjacent monitoring channels. If a multiplexing process is performed, the other channels are detected following the detection of the three adjacent monitoring channels. If at least one channel of the other channels or the lowest channel of the three adjacent monitoring channels is interrupted, the safety device gives an error message and the gate is correspondingly stopped or reversed or the like.

When the door has reached its closed position, the light curtain output after a certain time, for. B. after two seconds, operationally interrupted. If the two lowest channels become free again at the next door opening, the output switches on again.

When the door is first put into operation, at least one learning run is carried out at the normal speed with which the door is also operated later. The speed of the gate is detected at each location and stored in a memory. The gate edge may later pass through the light grid maximally with this location-dependent speed plus and / or minus a specified tolerance. A minimum opening and closing speed is preferably required only at the top between the uppermost channels K1 and K2 and between the lowest channels Kn-1 and Kn. The maximum tolerance can z. B. calculated from half speed and twice the speed of the door and selected.

Further advantages and features of the invention will become apparent from the other claims and the following description of a non-limiting embodiment of the invention, which is explained in more detail with reference to the drawings. In this drawing show:

1 1 is a schematic representation of a front view of a motorized door with a movable door leaf, a safety device with associated control circuit, a motor control door drive (controller) and a drive motor,

2 : a top view of the illustration after 1 , now with door guides and without control circuit, motor control door operator and drive motor,

3 : a schematic representation of a front view of a motorized door like 1 but now during closing, the gate is already partially closed,

4 : a flowchart for a blanking procedure with anti-trap protection with detection of the gate by the light grid and with timeout gate movement and timeout light curtain achieved for the training after the 1 to 3 .

5 : a flowchart similar 4 , but without the gate being recognized by the light curtain and without door movement timeout and light curtain timeout,

6 : a flowchart similar 4 , but without the gate being detected by the light curtain and without timeout light curtain, but with timeout door movement, and

7 : a flowchart similar 4 only with monitoring of the driving signal.

The motor-driven gate has a safety device 20 with a control circuit 21 , The control circuit 21 is with a motor control (controller) 22 connected, in turn, via an inverter 23 with a drive motor 24 communicates. The engine control 22 , the inverter 23 and the drive motor 24 are formed according to the prior art, they need not be discussed in detail here. The control circuit 21 is a store 25 assigned. The engine control 22 is a storage unit 27 assigned.

Out 2 are a left gate guide 26 and a right door guide 28 apparent, both are in 1 and 3 not shown in detail to better understand the drawing, in particular to show the light rays. The gate guides 26 . 28 lead a gate leaf 30 , This has a gate edge 32 with a lower door edge. The gate leaf 30 moves within a range of motion 34 , In 1 is the door leaf 30 drawn in the upper position, in 3 It is in an intermediate position, it is on the way down and has already covered about 1/2 of its way. The direction of movement is by an arrow 36 shown. When closed, the door leaf touches 30 with his Torunterkante a floor 38 , Between the ground 38 and the current position of the door leaf is in the representation of 1 a free part 40 of the range of motion 34 , This free part has the value zero if the bottom of the goal with the ground 38 is in contact.

The two gate guides 26 . 28 have z. B. a U-profile. This one has a base and two lateral thighs. In the base, a recess is provided. Behind this is at the left gate 26 a bar 42 for arranged in a row light emitter S1, S2 ... Sn arranged. On the opposite side, in the right door guide, behind the recess is a bar 44 for light receiver E1, E2 ... En arranged. The light emitter Sx and the light receiver Ex can work together in different pairs and form a channel in a certain pairing Sx with Ey. All channels together form a light grid.

The channels are hereinafter referred to on the one hand with transmitter S and receiver E, on the other hand, they are numbered. For example, the top channel is channel S1E1, and the bottom channel is channel SnEn. The channels with parallel light rays are called Kx in addition to the name SxEx. Out 1 It can be seen that the channels K1 to K5 are gleichabständig, their distance is D, D in the exemplary embodiment has the value 120 mm. The channels K5 to Kn are also equally spaced, with them the distance d = 40 mm. All light emitters and all light receivers are with the control circuit 21 connected, in 1 and 3 the connections are not shown.

The channels with parallel light beams advantageously run parallel to the lower door edge and / or to the floor 38 and / or at right angles to the direction of movement 36 , There are also channels with oblique beams of light, for example, the channels S4E5 and S5B4 are drawn. They cross each other.

In the direction of movement 36 has the gate edge 32 a dimension that has the value H. H is always greater than the distance between two adjacent parallel light emitters, here as d, the difference is at least 10%, in particular at least 20%. This covers the gate edge 32 always at least two parallel channels Kx - 1 and Kx from, in the embodiment shown, there are the channels K1 and K2. The gate edge 32 definitely covers two parallel channels K.

In the currently free part 40 of the range of motion 34 is an object 46 shown schematically. It interrupts channel K3. This channel is in the representation of 1 immediately below the lower edge of the gate.

It is not necessary the last 42 and 44 with the base of the gate guides 26 . 28 to connect, but advantageous. Alternatively, the strips 42 . 44 also elsewhere with the gate guide 26 respectively. 28 get connected. For example, a strip can be arranged on one side, for example on the flange of the outside of the door, while the other strip is arranged on a flange on the inside of the door. In this case, the gate edge interrupts 32 no longer the light rays across the entire width of the door leaf 30 but only on a part of this width. As before, the requirement is met that each light beam of a particular channel at least partially in the range of motion 34 located or from the gate edge 32 can be interrupted.

It is not necessary that the light emitter and light receiver on different sides of the door leaf 30 are arranged. At the place of the receiver E in 1 it is also possible to arrange mirrors, and the receivers can be arranged next to the transmitters.

The safety device 20 monitors, inter alia, three individual parallel channels K which are adjacent and with the gate edge 32 progressively. They are called adjacent monitoring channels. You always have the number three. Two of these monitoring channels are usually through the door leaf 30 covered, in 3 it is the channels K2 and K3. The third monitoring channel K4 is located near the lower edge of the door. He is the channel K with parallel beam, which is inside the free part 40 closer to the bottom edge of the door than any other parallel channels. This applies both to the gate opening and the gate closing. When opening the gate, the blanking device is normally without function, but it can also be used when opening the gate.

The three adjacent monitoring channels are each monitored together, this is done serially or in parallel. When the gate is moving, for example when the gate is out of position 3 moves upwards, the gate edge releases the channel K3 after a short distance. Once this is the case, a new grouping is formed, the three monitoring channels are then formed by the channels K1 and K2, see in particular 3 , as well as K3.

When the door is first put into operation, a learning run is carried out at maximum speed. The safety device 20 captures and stores the speed of the door leaf 30 at the location of each single channel K. The gate edge 32 the light grid may later pass through at a maximum of this location-dependent speed plus a defined tolerance v _max . A minimum opening and closing speed is required only at the top between the channels K1 and K2, there with the value v _minO and between the channels Kn - 1 and Kn, there with the value v _minU . The position of the gate is monitored with a timer. If the door stops automatically in a position where it interrupts the channels K1 or Kn-1, this results in an error signal. The time out on interruption of the channel K1 advantageously corresponds to a v _minO of z. B. 0.05 m / s, the time-out on interruption of the channel Kn - 1 corresponds to a speed v _minU of z. B. 0.01 m / s.

The polling of the individual light receivers preferably takes place in the multiplex method. Following the monitoring of the three monitoring channels will be the other channels that are in the free section 40 are located, queried and monitored. If at least one light beam of these further channels or the lower light beam of the three adjacent monitoring channels is interrupted, the safety device outputs 20 an error signal and stops the door leaf or the door, reverses or makes another safety movement.

The uppermost parallel channel K1 is mainly used for edge detection. An interruption of the light beam of this channel with objects other than the gate edge 32 only switches off the light curtain output and outputs an error signal with a time delay. K1 is therefore not directly intended for monitoring, but can be specified accordingly.

If the door remains open during opening and closing or by interruption of a light beam of a channel, the motor control can 22 set a test output before closing again from this position.

If an interruption occurs during a closing movement, the safety device remembers 20 the current butt edge position, it is in memory 25 abgespreichert. The safety device 20 counts each of the gate edge 32 run over parallel channels K. In the execution according to 3 these are the channels K1 to K3. The door movement is only released again when all light rays below this position are free. If this is the case, the new edge edge position is determined by the two upper monitoring channels.

If the gate is closed, the safety device interrupts 20 after two seconds of operation. If at the next door opening the lowest two channels K become free again, the output switches on again. If the door is closed, the light transmitters can be switched off for energy saving reasons and the test input can be set. The receiver should remain switched on. However, if the receiver is switched off, the output of the safety device remains after restarting 20 interrupted until all channels K are free. Only from this point on the gate recognition works again.

Based on 4 Now, the process of closing from the position according to 1 described. The gate leaf 30 is located above the light grid. The closing process starts with a closing command being entered at the Start position. This can be done via a button, a remote control or the like. The close command is also referred to as a trip signal for door closing. The closing command is located in the engine control 22 in front. After starting, the gate starts to move, it initially moves in the unmonitored area. At the same time, a test of the safety device 20 carried out. Testing is understood to mean complete testing, which not only checks whether the light grid is interrupted by an object, but also checks the functions of the light grid. Above an output line 31 reports the safety device 20 the test result. Only if the test is successful, the blanking is released. If the test is unsuccessful, a new test is performed. This until the test is successful. Blanking remains enabled only for a specified period of time. Within this time, the gate must reach the top channel K1. Reached the gate sheet 30 This top channel K1 is not within the specified period, it comes to a timeout and the blanking is stopped again. However, if the door reaches the channel K1 in the time span, ie below the timeout time, the blanking remains active. Just like the channel K1, the other channels are monitored one after the other. The gate edge 32 next interrupts channel K2. If this also happens within a specified time window, the blanking remains active. This goes on with all other channels. In the storage room 25 Among other things, a value table is stored, there is included when the learning run (determination from several learning trips), the individual channels Kx are run over one after the other. If the individual channels are reached in the specified time period, no timeout takes place. However, if this is not the case, the blanking stops. Thereafter, a new test takes place. If successful, the program jumps back up to the position 60 , so the output of the box "light curtain reached?" back. If the test is negative, at least one channel is cleared, the gate moves upwards. If the light curtain has detected this, the program jumps back to the position 60 , Blanking is active. But if the at least one channel is not cleared, the program jumps back to the position 62 , ie between "Timeout door movement?" and "Blanking stop". All channels still under the door edge are monitored. If an object is detected in them, the gate movement stops, the blanking is switched off.

In the execution after 4 a driving signal is determined by means of the light grid. Only a driving signal in the area of the light grid itself can be obtained via the light grid.

Alternatively, the drive signal can not be obtained via the light grid, but also on the drive itself, for example by means of a sensor 29 , the drive motor 24 assigned. Typically, Hall sensors are used to detect the rotation of the motor or its output shaft. Other sensors, such as rotary encoders, perforated discs with light scanning etc. are possible. By means of such a sensor, a driving signal is also obtained in the region above the light grid.

5 shows an embodiment in which the driving signal via such a sensor 29 is achieved as he is in 3 is drawn. The light grid is then used only insofar as the uppermost channel, the channel K1, is monitored to determine whether the door leaf 30 has reached this channel or not. The dual function of the other channels K2 to Kn, to be responsible for detecting a foreign object in the region of the light grid as well as for detecting the gate movement, is then not necessary. The door movement is no longer checked and detected by the channels K2 to Kn. In an advantageous development, the driving signal can be both via a sensor 29 as well as via the channels K1 to Kn.

The following will be 5 described: After the closing command "Start" the drive motor starts to turn, it becomes a driving signal over the sensor 29 output. If the drive signal is present, then (only then) the blanking is enabled. If there is no drive signal, the blanking remains stopped. If the drive signal is present, the blanking is now released until the light grid is reached, ie the channel K1 is interrupted. As long as this is not the case, the program jumps back to the position 62 So to the link immediately below "Start". However, once the light curtain has been reached, blanking remains active. Blanking remains active only as long as the drive signal is present. If the drive signal is present, see "yes", the blanking remains active. If the drive signal is not present, see "no", the blanking is stopped.

In training 6 is also, as in training after 5 monitoring the driving signal. In this case, however, it is not the uppermost channel of the light grid, ie the channel K1, which is monitored to see if the door reaches this channel. As long as the drive signal is present, the blanking remains enabled or active. If there is no travel signal, it is monitored whether a predetermined minimum time for timed door movement has already expired. If this is the case, the blanking is stopped. As long as this is not the case and a drive signal is present, the blanking remains active.

The execution after 7 corresponds to the execution after 6 , but now the monitoring of "Timeout door movement" is omitted. As long as there is a drive signal after the start command, ie the sensor 29 sends a signal, the blanking remains active. If there is no drive signal, blanking is stopped.

LIST OF REFERENCE NUMBERS

20

safety device

21

control circuit

22

Controller, engine control

23

inverter

24

drive motor

25

Memory (from 21 )

27

storage unit

26, 28

door guides

29

sensor

30

door leaf

31

output line

32

door edge

34

range of motion

36

movement direction

38

ground

40

free part

42, 44

Afford

60

position

62

position

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2374985 A1 [0002]
• EP 902157 B1 [0003]
• EP 902158 B1 [0003]

Claims (14)

Motor-driven gate, which is a safety device ( 20 ), a gate guide ( 26 . 28 ), a motor control ( 22 ), a movable door leaf ( 30 ) and a blanking device, the door leaf ( 30 ) has a gate edge ( 32 ) and moves within a range of motion ( 34 ), the safety device ( 20 ) detects a foreign object ( 46 ), which is in a free part ( 40 ) of the movement range ( 34 ) below the gate edge ( 32 ) and prevents a collision, the safety device ( 20 ) has a light grid, the light grid has a number of light emitters and a number of light receivers, the light grid has a plurality of channels, each channel is at least partially in the movement area, one of the light emitters Sx and one of the light receivers Ey each form a channel SxEy , the blanking device prevents the light grid from closing the closing door, which gradually passes over the individual channels ( 30 ) is evaluated as a foreign object, characterized in that the blanking device is normally inactive and is only activated when a closing command for the door leaf ( 30 ) in the engine control ( 22 ) and at least one of the following characteristics is met: a) a test of the safety device ( 20 ) successfully performed, b) there is a drive signal. Motor-driven door according to claim 1, characterized in that the blanking device is then activated when, after the closing command for the door leaf ( 30 ) both a test of the safety device ( 20 ) has been carried out successfully and a drive signal is present. Motor-driven door according to one of the preceding claims, characterized in that the driving signal via the individual parallel channels K of the safety device ( 20 ) and / or via a sensor ( 29 ), which is a drive motor ( 24 ) is assigned. Motor-driven gate according to one of the preceding claims, characterized in that the blanking device is active only as long as the door leaf ( 30 ) and / or a set time limit for reaching a detectable position of the door leaf ( 30 ) is not exceeded during its closing movement. Motor-driven gate according to one of the preceding claims, characterized in that the drive motor ( 24 ) drives the door at a location-dependent speed, that an expectation value for the interruption or release of the movement direction ( 36 ) the gate edge ( 32 nearest channel is calculated on the basis of the speed calculated, and that the safety device ( 20 ) only an error message is issued if the channel within the expected value plus and / or minus a tolerance value is reached. Motor-driven gate according to one of the preceding claims, characterized in that the door drive generates a drive signal of the door leaf, and that the drive signal at the safety device ( 20 ) is present. Motor-driven door according to one of the preceding claims, characterized in that the door drive generates a position signal of the door leaf, and that the position signal at the safety device ( 20 ) is present. Motor-driven gate according to one of the preceding claims, characterized in that the gate edge ( 32 ) within the range of movement ( 34 ) has a height which is greater than the distance of two adjacent channels, that the individual channels either the value zero, that is interrupted or the value 1, that is free, and that three adjacent monitoring channels are each monitored together, of which two in the area of the gate edge ( 32 ) and one below the gate edge ( 32 ) are located. Motor-driven gate according to claim 6, characterized in that the three adjacent monitoring channels are each channels K with parallel rays. Motor-driven gate according to one of claims 6 and 7, characterized in that when a closing movement of the gate down the three adjacent monitoring channels normally provides the bit pattern 001, and that when the lower of the three adjacent monitoring channels provides the value zero, a new grouping of the three adjacent monitoring channels takes place, in which now the previously upper channel is omitted and a channel has been added below the previously lower channel. Motor-driven gate according to one of the preceding claims, characterized in that the free part ( 40 ) of the movement range ( 34 ) below the gate edge ( 32 ) is also monitored with oblique channels SxEy, in particular with cross beams. Motor-driven gate according to one of the preceding claims, characterized in that the safety device ( 20 ) has a counting circuit which detects how many channels the gate edge ( 32 ) during the closing movement already has covered or has not yet released at the opening movement. Motor-driven gate according to one of the preceding claims, characterized in that in the fully open position of the door leaf ( 30 ) of the gate edge ( 32 ) nearest channel K1, which has a parallel beam, is not part of the monitoring height of the light grid and is preferably used only for edge detection. Motor-driven gate according to one of the preceding claims, characterized in that the blanking device in the safety device ( 20 ) is arranged.

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