JP6632196B2 - Electric blinds - Google Patents

Description

  The present invention relates to an electric blind.

  In the electric blind, a plurality of slats are rotatably supported by rotation of the electric motor by a ladder cord hanging from the head box, and a lifting cord hanging from the head box is rotated by the electric motor. There is a type in which a bottom rail is supported so as to be able to move up and down by being wound or unwound on a winding shaft arranged in a head box with the above (for example, see Patent Document 1).

JP 2008-127890 A

  When the electric blind of Patent Literature 1 is arranged between two glass plates, a phenomenon occurs in which the bottom rail collides with the glass when the bottom rail is raised or lowered. Investigation of the cause revealed that the bottom rail may swing back and forth when the bottom rail is raised or lowered.

  The present invention has been made in view of such circumstances, and provides an electric blind capable of suppressing the bottom rail from swinging in the front-rear direction when the bottom rail is raised or lowered.

  According to the present invention, a plurality of slats are rotatably supported by the rotation of the electric motor by the slat support cords suspended from the head box, and the lifting cords suspended from the head box are provided by the slat support cords of the electric motor. In an electric blind configured such that the bottom rail is supported so as to be able to move up and down by being wound or unwound on a winding shaft arranged in the head box with rotation, the rotation of the electric motor is controlled. The control unit, wherein the second rotation speed of the electric motor during rotation of the slat accompanying the raising or lowering operation of the bottom rail, the bottom rail without rotating the slat Controlling the electric motor to be lower than a first rotation speed of the electric motor when raising or lowering the motor Configured so that, electric blind is provided.

  A more detailed investigation of the cause of the bottom rail swaying in the front-rear direction revealed that the rotation speed of the electric motor during rotation of the slats due to the raising or lowering operation of the bottom rail caused the bottom rail to rise or fall without rotating the slat. Since the rotation speed of the electric motor at the time of lowering is the same as that of the electric motor, the rotation speed of the slat is increased, which leads to the swinging of the bottom rail in the front-rear direction. Based on such knowledge, the rotation speed of the electric motor during rotation of the slats due to the raising or lowering operation of the bottom rail, the rotation of the electric motor when raising or lowering the bottom rail without rotating the slats By controlling the electric motor to be slower than the speed, it has been found that the swing of the bottom rail can be suppressed, and the present invention has been completed.

Hereinafter, various embodiments of the present invention will be exemplified. The various embodiments described below can be combined with each other.
Preferably, three or more lifting cords are provided apart from each other in the longitudinal direction of the slat, and two lifting cords at both ends are arranged at positions biased to one side in the front-rear direction of the slat, and the remaining The lifting cord is arranged at a position deviated to the other side in the front-rear direction of the slat.
Preferably, the control unit rotates the electric motor at a second rotation speed when determining that the inclination angle of the slat is within a predetermined range when receiving a command to raise or lower the bottom rail. It is configured to rotate at the first rotation speed without causing the rotation.
Preferably, the control unit controls the electric motor such that a third rotation speed of the electric motor when rotating the slat based on the rotation command of the slat is equal to or less than a second rotation speed. Configured to control.

1 shows an electric blind 1 according to an embodiment of the present invention, in which (a) is a front view and (b) is a right side view. FIG. 2 is an enlarged view showing a configuration near a drum unit 19 at a left end in FIG. (A) is a cross-sectional view of the uppermost slat 7 as viewed from above, (b) is a cross-sectional view of the second slat 7 as viewed from above, and (c) is a three-level view from above. It is sectional drawing seen from the upper part of the slat 7 after eyes. In (a) and (b), the slat retainer 31 is omitted. FIGS. 3A and 3B are cross-sectional views taken along the line AA in FIG. 3C, wherein FIG. 3A shows a fully closed state and FIG. 3B shows a reverse fully closed state. It is explanatory drawing of the principle which the looseness detection switch 36 operates, (a)-(b) shows the state in which tension is added to the raising / lowering tape 11, (c)-(d) is the state in which the raising / lowering tape 11 was loosened. Is shown. 2A and 2C are schematic views of a cross section taken along line BB in FIG. 2, and FIGS. 2B and 2D are sliders 35 and a slack detection switch of FIGS. 2A and 2C, respectively. 36 shows a state when viewed from above. FIG. 2 is a block diagram illustrating a configuration of a control unit 20 and members connected to the control unit 20. (A) to (d) are graphs showing the relationship between the elapsed time after the control unit 20 receives a command to raise or lower the bottom rail 9 and the rotation speed of the electric motor 2, and (a) is a conventional technique. , (B)-(d) show three embodiments of the present invention. 6 is a flowchart illustrating a control flow when the control unit 20 receives a command to raise or lower the bottom rail 9. 9 is a flowchart illustrating a control flow when the control unit receives a rotation command of the slat.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Various features in the embodiments described below can be independently established and combined with each other.

  The “elevating cord” in the claims is a cord used for elevating the bottom rail, and its cross-sectional shape is not limited. Therefore, the "elevating cord" may be either an elevating tape in the form of a thin and wide tape or a string-shaped elevating string. Further, the "winding shaft" in the claims may be any of a winding drum for stacking and winding the elevating tape and a winding cone for spirally winding the elevating string. In the following embodiment, a horizontal blind of a type in which an elevating tape is stacked and wound on a winding drum will be described as an example, but a horizontal blind of a type in which an elevating string is spirally wound around a winding cone is also basically used. A similar operation and effect can be achieved.

Hereinafter, an electric blind 1 according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the electric blind 1 includes a head box 3, a ladder cord 5 suspended from the head box 3, and a lifting tape 11. As shown in FIG. 3, the ladder cord 5 includes a plurality of wefts 5b between a pair of warps 5a. A slat 7 is supported on each weft yarn 5b. The ladder cord 5 is fixed to the uppermost slat 7 and the next slat 7 with a slat retainer 31. The ladder code 5 corresponds to a “slat support code” in the claims. The configuration of the “slat support cord” is not limited as long as it can support and rotate the slat 7. For example, the “slat support cord” includes two warps separated from each other, and one warp is attached to one edge of the slat. It may be so configured that the other warp is attached to the other edge of the slat. The elevating tape 11 is a thin and wide tape.

  As shown in FIG. 1, the electric motor 2, the motor bracket 33, the motor joint 34, the drive shaft 23, the drum unit 19, the upper limit switch 4, the encoder 38, the power supply board 41 and a control board 43 are arranged.

  A switching power supply circuit is mounted on the power supply board 41, and this circuit converts AC power input from the external power input unit 42 into DC power. The various parts (the electric motor 2, the control board 43, etc.) of the electric blind 1 are driven by the converted DC power. An electronic circuit for configuring the control unit 20 shown in FIG. 6 is mounted on the control board 43. As shown in FIG. 6, the control unit 20 is realized by the CPU 25 executing various processes according to a program stored in the storage unit 26. The CPU 25 drives the electric motor 2 via the motor drive circuit 2a. The CPU 25 is communicably connected to the encoder 38 via the encoder connection circuit 38a. Further, the CPU 25 is communicably connected to the upper limit switch 4 and the looseness detection switch 36.

  The control unit 20 is configured to be able to receive commands from a wired remote controller 46, an infrared remote controller 47, a wireless remote controller 48, or a PC (personal computer) 49. The control unit 20 communicates with the infrared remote controller 47 through the infrared light receiving unit 47a, and communicates with the wireless remote controller 48 through the wireless receiver 48a. Examples of the commands that can be received by the control unit 20 include a command to start the raising or lowering operation of the bottom rail 9, a command to rotate the slat in the forward or backward fully closing direction, a command to stop the operation, and the like.

  The electric motor 2 is fixed to the head box 3 via a motor bracket 33. The rotation of the electric motor 2 is transmitted to the drive shaft 23 via the motor joint 34. The upper limit switch 4 is a switch that detects whether the slat 7 has been raised to the upper limit. The switch 4 has a protruding portion 4a that protrudes downward from the headbox 3. When the uppermost slat 7 pushes up the protruding portion 4a of the switch 4, the switch 4 outputs a detection signal. The control unit 20 is configured to stop the rotation of the drive shaft 23 when receiving the detection signal from the switch 4.

  The encoder 38 is configured to detect the rotation angle of the drive shaft 23. Specifically, the encoder 38 outputs a pulse signal each time the drive shaft 23 rotates a predetermined angle. The control unit 20 detects the rotation angle of the drive shaft 23 by counting the number of pulses. The control unit 20 can control the electric motor 2 to rotate the drive shaft 23 at a preset speed by using a pulse signal from the encoder 38. Further, the control unit 20 can calculate the inclination angle of the slat 7 at any time by detecting the rotation angle of the drive shaft from the time when the slat 7 is in the forward or reverse fully closed state. Has become.

  As shown in FIG. 2, the drum unit 19 includes a support member 21 fixed to the head box 3, a ladder cord suspension member 27 and a winding drum 29 rotatably supported by the support member 21, and a support member 21. The slider 35 includes a slider 35 slidably supported by the support member 21 and a slack detection switch 36 fixed to the support member 21.

  One end of a pair of warp threads 5 a of the ladder cord 5 is attached to a ladder cord suspension member 27, and the ladder cord suspension member 27 rotates with the rotation of the drive shaft 23, whereby the inclination angle of the slat 7 is increased. Are configured to change. The ladder cord suspension member 27 moves with the rotation of the drive shaft 23 until the slat 7 is in the fully closed state as shown in FIG. 4A or the reverse fully closed state as shown in FIG. 4B. After that, the drive shaft 23 rotates idly with respect to the ladder cord suspension member 27. The other ends of the pair of warps 5 a of the ladder cord 5 are attached to a bottom rail 9. In addition, as shown in FIG. 4A, the fully closed state means a state in which the slat 7 is rotated in a direction in which the outside of the room of the slat 7 is lowered until the drive shaft 23 idles. The closed state means a state in which the slat 7 is rotated until the drive shaft 23 idles in a direction in which the outside of the room of the slat 7 rises, as shown in FIG. 4B.

  The lifting tape 11 has one end attached to the bottom rail 9 and the other end attached to the winding drum 29. When the winding drum 29 rotates with the rotation of the drive shaft 23, the lifting tape 11 is wound or unwound with respect to the winding drum 29, so that the bottom rail 9 is moved up and down.

  The slider 35 is supported by the support member 21 so as to be slidable in the front-back direction of the head box 3. When the bottom rail 9 has not reached the lower limit, as shown in FIGS. 5A and 5B, the lifting tape 11 is tensioned and the force F1 shown in FIG. Is pressed. In this state, no detection signal is output from the switch 36. On the other hand, when the bottom rail 9 reaches the lower limit or collides with an obstacle while the bottom rail 9 is descending, as shown in FIGS. As a result, the force F1 becomes smaller, so that the urging force F2 applied to the slider 35 by the protrusion 36a becomes larger than the force F1. As a result, as shown in FIG. 5D, the slider 35 is pushed by the protrusion 36a and moves in the direction of arrow DF, and the switch 36 outputs a detection signal. The control unit 20 is configured to stop the rotation of the drive shaft 23 when receiving the detection signal from the switch 36 while the bottom rail 9 is descending.

  As shown in FIG. 3, three lifting tapes 11 are provided apart from each other in the longitudinal direction LS of the slat 7. As shown in FIGS. 3A and 3B, the two lifting tapes 11 at both ends are suspended along the edge 7 f inside the room of the slats 7 for the slats 7 at the uppermost stage and the next stage, As shown in FIG. 3C, the slats 7 in the third and subsequent stages from the top are inserted into the insertion holes 7a provided in the slats 7. The insertion hole 7a is arranged at a position deviated inside the room of the slat 7 (one side in the front-rear direction). Specifically, the insertion hole 7a is disposed near the edge 7f inside the room of the slat 7. With such a configuration, the two elevating tapes 11 at both ends are arranged at positions deviated more toward the inside of the room than the center of the slat 7 in the front-rear direction. The insertion hole 7a has an elongated shape, and is arranged such that the longitudinal direction of the insertion hole 7a is parallel to the longitudinal direction LS of the slat 7. Since the insertion holes 7a are arranged in this manner, as shown in FIG. 4A, when the slats 7 are fully closed, the insertion holes 7a are shielded by the slats 7 on the near side, and external light is blocked. Since S is prevented from entering the room through the insertion hole 7a, light leakage in the fully closed state is reduced.

  As shown in FIG. 3A, the elevating tape 11 at the center is inserted into the insertion hole 7c provided in the slat 7 with respect to the uppermost slat 7, and as shown in FIG. The slats 7 of the tier are suspended along the outer edge 7b of the room of the slats 7, and as shown in FIG. Is inserted through the annular portion 5c. It is not necessary to insert the lifting tape 11 into the annular portion 5c provided at a position corresponding to all the slats 7. In the present embodiment, the lifting tape 11 is not inserted into the annular portion 5c at the position corresponding to the slats 7 of the first to fifth stages, and the annular portion 5c provided at the position corresponding to the slat 7 of the sixth stage is not inserted. The lifting tape 11 is inserted therethrough. The insertion hole 7c of the uppermost slat 7 is arranged at a position biased toward the outside of the room of the slat 7 (the other side in the front-rear direction). Specifically, the insertion hole 7c is arranged near the outer edge 7b of the room of the slat 7. With such a configuration, the elevating tape 11 at the center is disposed at a position deviated to the outside of the room from the center of the slat 7 in the front-rear direction. The insertion hole 7c has an elongated shape, and is arranged such that the longitudinal direction of the insertion hole 7c is parallel to the longitudinal direction LS of the slat 7. Since the insertion hole 7c is arranged in this manner, when the slat 7 is fully closed, the portion of the insertion hole 7c overlaps the second-stage slat 7, so that the light passing through the insertion hole 7c Reflected by the tiered slats. For this reason, since the outside light S is prevented from entering the room through the insertion hole 7c, light leakage in the fully closed state is reduced.

  Next, the raising and lowering operation of the electric blind 1 will be described. The following description will be made on the assumption that the initial state of the electric blind 1 is a state in which the bottom rail 9 is at the lower limit position and the slat 7 is in a horizontal state as shown in FIG.

  When the control unit 20 receives a command to raise the bottom rail 9 in the state of FIG. 1, the control unit 20 rotates the electric motor 2 so that the drive shaft 23 rotates in the direction of the arrow U in FIG. Then, the raising operation of the bottom rail 9 is started. When the drive shaft 23 rotates in the direction of the arrow U, the winding drum 29 and the ladder cord suspension member 27 also rotate in the direction of the arrow U, and the winding of the elevating tape 11 is started. 4 (b) is rotated in the reverse fully closed direction indicated by the arrow RT. When the ladder cord suspension member 27 is rotated until the slat 7 is in the reverse fully closed state, the drive shaft 23 idles with respect to the ladder cord suspension member 27 thereafter, and the rotation of the slat 7 is completed. . Thereafter, only the take-up drum 29 rotates and the lifting tape 11 is taken up by the take-up drum 29, so that the slat 7 does not rotate and the bottom rail 9 rises. For example, when the control unit 20 receives a command to stop the rotation of the drive shaft 23 when the bottom rail 9 has risen to near the center in the height direction, the control unit 20 stops the rotation of the electric motor 2.

  Next, when the control unit 20 receives a command to lower the bottom rail 9, the control unit 20 rotates the electric motor 2 so that the drive shaft 23 rotates in the direction of arrow D in FIG. Start the lowering operation. When the drive shaft 23 rotates in the direction of the arrow D, the winding drum 29 and the ladder cord suspension member 27 also rotate in the direction of the arrow D, and the rewinding of the elevating tape 11 is started. 4 (a) is rotated in the forward and fully closed direction indicated by the arrow NT. When the ladder cord suspension member 27 is rotated until the slat 7 is fully closed, the drive shaft 23 idles with respect to the ladder cord suspension member 27 thereafter, and the rotation of the slat 7 is completed. . Thereafter, only the take-up drum 29 rotates and the elevating tape 11 is rewound from the take-up drum 29, so that the slat 7 does not rotate and the bottom rail 9 descends.

  Conventionally, as shown in FIG. 7A, when the control unit 20 receives a command to raise or lower the bottom rail 9, the electric motor 2 immediately starts rotating at the rotation speed V1, and the slats 7 move forward or backward. Before and after the fully closed state, the rotation speed of the electric motor 2 was substantially the same. That is, the rotation speed of the electric motor 2 during the rotation of the slat 7 is substantially the same as the rotation speed of the electric motor 2 after the rotation of the slat 7 is completed. For this reason, the rotation speed of the slats 7 increases, causing the bottom rail 9 to swing back and forth. Note that such a phenomenon occurs regardless of the arrangement method of the lifting tape 11. However, as in the present embodiment, the two lifting tapes 11 at both ends are biased to one side in the front-rear direction of the slat 7. When the slat 7 is rotated, the center of gravity of the slat 7 is shifted in the front-rear direction when the remaining lifting tape 11 is disposed in a position deviated to the other side in the front-rear direction of the seven slats. Since the bottom rail 9 is easily moved, the swing of the bottom rail 9 is more likely to be remarkable than that of an electric blind in which the lifting tape 11 is inserted substantially at the center of the slat 7 in the front-rear direction. The need to adopt means is particularly great.

  In this embodiment, the rotational speed of the electric motor 2 is controlled as shown in FIG. 7B to suppress the swing of the bottom rail 9. In FIG. 7B, the electric motor 2 rotates at the rotation speed V2 (<V1) from when the control unit 20 receives the command to raise or lower the bottom rail 9 until the rotation of the slat 7 is completed. When the rotation of the slat 7 is completed, the electric motor 2 is controlled to rotate at the rotation speed V1. According to such a control method, since the slat 7 is rotated at a lower speed than in the related art, the swing of the bottom rail 9 due to the rotation of the slat 7 is suppressed. Here, V2 = α · V1, and α is, for example, 0.1 to 0.9, preferably 0.3 to 0.7.

Here, a control flow when the control unit 20 receives a command to raise or lower the bottom rail 9 will be described with reference to FIG.
First, in step SA1, the control unit 20 determines whether or not the inclination angle of the slat 7 is within a predetermined range. The predetermined range is set to a range in which the slats 7 can be said to be substantially reverse fully closed when the bottom rail 9 is raised, and the slats 7 are substantially fully closed when the bottom rail 9 is lowered. It is set in the range that can be said to be. Specifically, for example, when the bottom rail 9 is raised, the predetermined range is set within a predetermined range (eg, ± 20 degrees or ± 10 degrees) from the inclination angle of the slat 7 in the reverse fully closed state. When the slat 7 is lowered, the slat 7 is set to a predetermined range (eg, ± 20 degrees or ± 10 degrees) from the inclination angle of the slat 7 in the fully closed state.

  If the tilt angle of the slat 7 is out of the predetermined range when the control unit 20 receives the command to raise or lower the bottom rail 9 (N in step SA1), in step SA2, the control unit 20 executes the process shown in FIG. As shown in b), the electric motor 2 is rotated at the rotation speed V2 to rotate the slats 7 and start winding or rewinding the elevating tape 11.

  Next, in step SA3, the control unit 20 checks whether the rotation of the slat 7 has been completed. Whether or not the rotation of the slat has been completed can be determined based on whether or not the inclination angle of the slat 7 is within a predetermined range, as in step SA1. If the rotation of the slat 7 has not been completed (N in step SA3), the process returns to step SA2, and the rotation of the electric motor 2 at the rotation speed V2 is continued. On the other hand, when the rotation of the slat 7 is completed (Y in step SA3), in step SA4, the control unit 20 increases the rotation speed of the electric motor 2 to V1 and moves up and down as shown in FIG. The winding or rewinding of the tape 11 is continued.

  On the other hand, when the inclination angle of the slat 7 when the controller 20 receives the command to raise or lower the bottom rail 9 is within a predetermined range (Y in step SA1), the slat 7 is substantially rotated. The controller 20 rotates the electric motor 2 at the rotation speed V1 in step SA4 without rotating the electric motor 2 at the rotation speed V2, so that the bottom rail 9 starts ascending or descending. The winding or rewinding of the tape 11 is started.

  Next, in step SA5, the control unit 20 determines whether or not the bottom rail 9 has reached the upper or lower limit position, and when the bottom rail 9 has reached the upper or lower limit position (Y in step SA5). Then, the rotation of the electric motor 2 is stopped. On the other hand, if the bottom rail 9 has not reached the upper or lower limit position (N in step SA5), in step SA7, the control unit 20 receives a stop command to stop the raising or lowering operation of the bottom rail 9. Check if it is. When the stop input is input (Y in step SA7), the control unit 20 stops the electric motor 2 in step SA6. On the other hand, when the stop input has not been input (N in step SA7), the process returns to step SA4.

  When the slat 7 is rotated based on the rotation command of the slat 7 irrespective of the elevation of the bottom rail 9, the electric motor 2 is controlled to rotate at a rotation speed V3 (≦ V2). Is preferred. In this case, there is an advantage that the inclination angle of the slat 7 can be easily adjusted. V3 = β · V2, β is, for example, 0.1 to 1, and preferably 0.3 to 0.7.

Here, a control flow when the control unit 20 receives a rotation command of the slat 7 will be described with reference to FIG.
First, in step SB1, the control unit 20 rotates the electric motor 2 at the rotation speed V3 to rotate the slat 7.

  Next, in step SB2, the control unit 20 checks whether the rotation of the slat 7 has been completed. Whether or not the rotation of the slat 7 has been completed can be determined based on whether or not the inclination angle of the slat 7 is within a predetermined range, as in step SA1. If the rotation of the slat 7 has not been completed (N in Step SB2), in Step SB3, the control unit 20 checks whether a stop command to stop the rotation of the slat 7 has been input. If the stop input has not been input (N in step SB3), the process returns to step SB1.

  On the other hand, when the rotation of the slat 7 is completed (Y in step SB2) or when a stop input is input (Y in step SB3), the control unit 20 stops the electric motor 2 in step SB4.

This embodiment can be implemented in the following modes.
From the viewpoint of quickly raising and lowering the bottom rail 9, it is preferable to increase the rotation speed of the electric motor 2 to V1 immediately after the rotation of the slat 7 is completed as shown in FIG. In this case, it is necessary to determine whether or not the rotation of the slat 7 has been completed, and determine the rotation speed of the electric motor 2, so that the control is complicated. In order to simplify the control, in FIG. 7C, the rotation speed of the electric motor 2 is controlled so as to increase the rotation speed of the electric motor 2 after a predetermined time t has elapsed. The predetermined time t is preferably the same as the time t1 required for the slat 7 to rotate from one of the forward fully closed state and the reverse fully closed state to the other, or a time t2 longer than t1. With this setting, the swing of the bottom rail 9 can be suppressed with simple control. The upper limit of t2 is not particularly limited, but is, for example, five times t1.

7 (b) to 7 (c), the rotation speed V2 of the electric motor 2 is controlled to be substantially constant during the rotation of the slat 7, but as shown in FIG. The rotation speed of the electric motor 2 may be gradually increased during the rotation of the motor 7. In this case, since the rotation speed of the electric motor 2 changes slowly, the swing of the bottom rail 9 can be more effectively suppressed.

1: Horizontal blind, 2: Electric motor, 3: Head box, 4: Upper limit switch, 5: Ladder code, 7: Slat, 9: Bottom rail, 11: Elevating tape, 19: Drum unit, 21: Support member, 23 : Drive shaft, 25: CPU, 26: storage unit, 27: ladder cord suspension member, 29: winding drum, 31: slat retainer, 33: motor bracket, 34: motor joint, 35: slider, 36: looseness detection Switch, 38: encoder

Claims (2)

A plurality of slats are rotatably supported by the rotation of the electric motor by the slat support cords hanging from the head box, and the lifting / lowering cords hanging from the head box are rotated by the rotation of the electric motor. In an electric blind configured such that the bottom rail is supported so as to be able to move up and down by being wound or unwound on a winding shaft arranged in a box,
A control unit for controlling the rotation of the electric motor,
The second rotation speed of the electric motor during the rotation of the slats accompanying the raising or lowering operation of the bottom rail, when the control unit raises or lowers the bottom rail without rotating the slats The electric motor is configured to be controlled to be lower than a first rotation speed of the electric motor,
The lifting cord is provided in three or more spaced apart in the longitudinal direction of the slat,
The two lifting cords at both ends are arranged at positions biased to one side in the front-back direction of the slat,
The remaining lifting / lowering cords are arranged at positions biased to the other side in the front-rear direction of the slats ,
The control unit controls the electric motor such that a third rotation speed of the electric motor when rotating the slat based on the rotation command of the slat is equal to or less than a second rotation speed. configured Ru, electric blind to. The control unit, when determining that the inclination angle of the slat is within a predetermined range when receiving the command of the raising or lowering operation of the bottom rail, without rotating the electric motor at a second rotation speed The electric blind of claim 1, configured to rotate at a first rotational speed.