Rotational resistance device

Abstract

To provide a novel rotational resistance device that allows a rotating body to sufficiently return in an opposite direction after the rotating body completes driven rotation in one direction.SOLUTION: A rotational resistance device comprises: a housing 4 rotatable about a common rotational axis; an operation plate 6 stored in the housing; a compression coil spring 8; and a torque limiter 10. The operation plate 6 is rotatable relative to the housing 4 about the rotational axis o of the rotating body within a predetermined angle range. The compression coil spring 8 is disposed between the operation plate 6 and the housing 4 and generates a relatively small reactive torque when the housing 4 rotates relative to the operation plate 6. The torque limiter 10 has a first member 46 and a second member 48 that are rotatable relative to each other about the rotational axis o, and a connecting member 50 that connects the first member 46 and the second member 48 with a relatively large resistant torque. Either one of the first member 46 and the second member 48 is connected to the operation plate 6, and the other is connected to fixing means.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotational resistance device. [Background technology]

[0002] Rotational resistance devices that apply resistance to a rotating body are widely used. For example, rotational resistance devices are used in a known typesetting printer known as a hot printer. In a hot printer, a long strip of printer tape coated with heat-sensitive ink is used as a printing medium. The printer tape is initially wound around one roller. As the printer tape is wound from one roller to the other roller, it is pressed against the surface being printed on between the first and second rollers. When the printer tape is pressed against the surface being printed on, the ink coated on the printer tape is printed on the surface being printed on. The other roller winds the printer tape from the first roller, and a driving source such as a motor is connected to the other roller. Therefore, the first roller is the driven side, and the other roller is the driving side. If slack occurs in the printer tape between the first and second rollers when the other roller winds the printer tape, the pressure contact becomes insufficient, and the ink coated on the printer tape may not be properly printed on the surface being printed on. To prevent this deflection, a rotation resistance device is incorporated into one of the rollers on the driven side, which rotates against a predetermined resistance torque provided by the rotation resistance device.

[0003] Conventionally, a torque limiter such as that disclosed in Patent Document 1 below has been used as the rotation resistance device. This torque limiter includes a first member and a second member that are rotatable relative to each other around a rotation axis, and a connecting member that connects the first member and the second member with a predetermined resistance torque. The first member has a cylindrical inner circumferential surface, and the second member has a cylindrical outer circumferential surface. The inner circumferential surface of the first member faces the outer circumferential surface of the second member (therefore, the first member corresponds to a so-called outer ring, and the second member corresponds to a so-called inner ring). The connecting member is a torsion coil spring that is composed of a wound portion around which a wire is wound and a pair of hook portions provided on both ends of the wound portion. In a free state, the inner diameter of the wound portion is smaller than the outer diameter of the second member, and the wound portion is attached to the outer circumferential surface of the second member in a slightly expanded state. The pair of hooks are engaged with hook engagement portions formed on the inner circumferential surface of the first member, and when the first member and the second member rotate relative to each other around the rotation axis, one of the pair of hooks is pushed by the hook engagement portion in a direction that weakens the tightening of the torsion coil spring, generating the predetermined resistance torque. Therefore, if one of the first member and the second member is connected to a roller and the other is connected to a fixing means, the one roller that rotates following the rotation will rotate against the predetermined resistance torque of the torsion coil spring, and the required resistance will be applied to the one roller. Note that although the torque limiter shown in Patent Document 1 below is a bidirectional torque limiter having a pair of hooks, a unidirectional torque limiter having a single hook can also be used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-112568 Summary of the Invention [Problem to be solved by the invention]

[0005] When the torque limiter disclosed in Patent Document 1 is applied as a rotation resistance device to the driven roller (one of the rollers) of the hot printer described above, the following problem can occur. Even when the rotation of the other roller (the driving roller) stops, the rotation of the driven roller (one of the rollers) does not stop immediately but stops after a certain delay due to inertia, resulting in slack in the printer tape between the one roller and the other roller. In the torque limiter disclosed in Patent Document 1, the first and second members are connected by a torsion coil spring. When the first and second members rotate relative to each other, one of the pair of hook portions of the torsion coil spring is pressed by the hook engaging portion in a direction that loosens the tightening of the torsion coil spring. Therefore, when the relative rotation stops, the spring force of the torsion coil spring (so-called springback) causes the one roller to rotate in the opposite direction, thereby eliminating some of the slack. However, according to the inventors' experience, the springback alone is not enough to fully eliminate the slack in the printer tape.

[0006] The present invention has been made in view of the above circumstances, and its main technical object is to provide a new and improved rotational resistance device that can cause a rotating body to fully rotate back in the opposite direction after the rotating body has completed its driven rotation in one direction. It should be noted that the above object is not limited to applications of rotational resistance devices in hot printers. [Means for solving the problem]

[0007] According to the present invention, there is provided a rotational resistance device that solves the above-mentioned main technical problem, which applies resistance to a rotating body, comprising: The torque limiter includes a housing rotatable about a common rotation axis, and an operating plate, a compression coil spring, and a torque limiter housed in the housing, the actuation plate is rotatable around the rotation axis relative to the housing within a predetermined angle range; the compression coil spring is disposed between the actuation plate and the housing and generates a relatively small repulsive torque when the housing rotates relative to the actuation plate; The torque limiter has a first member and a second member that are rotatable relative to each other around the rotation axis, and a connecting member that connects the first member and the second member with a relatively large resistance torque, and one of the first member and the second member is connected to the operating plate, and the other is connected to a fixing means, characterized in that the rotation resistance device is provided.

[0008] Preferably, the housing has an end plate disposed perpendicular to the rotation shaft, the end plate is formed with a sector-shaped locking recess extending around the rotation shaft, and the actuation plate is formed with a sector-shaped locking protrusion extending around the rotation shaft, the circumferential length of the locking protrusion is shorter than the circumferential length of the locking recess, the locking protrusion is fitted into the locking recess, and the locking protrusion is pressed relatively by the housing in the locking recess. In this case, it is preferable that the locking recess and the locking protrusion are both disposed one on each side in the diameter direction. Preferably, the housing has an end plate disposed perpendicular to the rotation shaft, the end plate having a one-side support protrusion formed thereon that protrudes in the axial direction, the operating plate having a base disposed perpendicular to the rotation shaft and an other-side support protrusion formed by locally increasing the outer diameter of the base, and both ends of the compression coil spring are supported by one circumferential side surface of the one-side support protrusion and the other circumferential side surface of the other-side support protrusion. In this case, it is preferable that the one-side support protrusion, the other-side support protrusion, and the compression coil spring are disposed one on each side in the diametrical direction. [Effects of the Invention]

[0009] In a rotation resistance device constructed according to the present invention, when a driving torque is applied to the rotor to rotate it in one direction, the actuating plate is initially held in place by the resistance torque of the connecting member of the torque limiter, and the housing is rotated in one direction relative to the actuating plate against the spring force of the compression coil spring. At this time, the resistance torque of the connecting member is greater than the repulsive torque of the compression coil spring, so the actuating plate is securely held in place by the resistance torque. After the housing rotates a predetermined angle, the housing and the actuating plate are rotated in one direction against the resistance torque. Then, when the driving torque applied to the rotor is released, i.e., when the rotor's rotation in one direction is terminated, the actuating plate is held in place by the relatively large resistance torque of the connecting member of the torque limiter, and the housing is rotated in the opposite direction relative to the actuating plate by the relatively small repulsive torque of the compression coil spring. The distance by which the housing is rotated in the opposite direction can be appropriately adjusted by, for example, the length of the compression coil spring. Therefore, according to the present invention, there is provided a rotation resistance device in which, when the driven rotation of the rotating body in one direction is terminated, the rotating body is caused to rotate fully back in the opposite direction. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing the overall configuration of a preferred embodiment of a rotational resistance device constructed according to the present invention; [Figure 2] FIG. 2 is an exploded perspective view of the rotational resistance device shown in FIG. 1, showing each component part. [Figure 3] FIG. 2 is a view showing the housing of the rotation resistance device shown in FIG. 1 by itself. [Figure 4] FIG. 2 is a view showing the actuation plate of the rotation resistance device shown in FIG. 1 alone. [Figure 5] 2 is a diagram for explaining the operation of the rotation resistance device shown in FIG. 1; DETAILED DESCRIPTION OF THE INVENTION

[0011] A more detailed description of a rotational resistance device constructed according to the present invention will be given below with reference to the accompanying drawings showing preferred embodiments thereof. In the following description, unless otherwise specified, "one axial side" and "other axial side" refer to the left side and "other axial side" respectively, based on the state shown in the AA cross-sectional view of Fig. 1 . Furthermore, in the following description, unless otherwise specified, "one circumferential side" and "other circumferential side" refer to the other axial side, i.e., the clockwise side as viewed from the right side of the AA cross-sectional view of Fig. 1 , and "other circumferential side" refers to the counterclockwise side.

[0012] Referring to Figures 1 and 2, the rotation resistance device, generally designated by the numeral 2, includes a housing 4, an operating plate 6, a compression coil spring 8, and a torque limiter 10, all of which are housed in the housing 4.

[0013] The housing 4 is fixed to a rotating body (not shown), such as a roller, by an appropriate fixing means, and is rotatable around a common rotation axis o. Referring also to FIG. 3, in the illustrated embodiment, the housing 4 is composed of a first housing body 12 shown in FIG. 3(a) and an opposite housing body 14 shown in FIG. 3(b). Both the first housing body 12 and the opposite housing body 14 are formed from an appropriate synthetic resin. Starting with the first housing body 12, the first housing body 12 is composed of a circular first end plate 16 disposed perpendicular to the axial direction and a cylindrical first outer peripheral wall 18 extending from the outer periphery of the first end plate 16 to the other axial direction. A circular through-hole 20 is formed in the center of the first end plate 16, penetrating it in the axial direction. A fan-shaped locking recess 22 extending around the rotation axis o is formed on the other axial side surface of the first end plate 16. In the illustrated embodiment, two locking recesses 22 are formed at equal angular intervals in the circumferential direction, and a fan-shaped locked protrusion 24 remains between the two locking recesses 22. Therefore, there are two locked protrusions 24. A one-side support protrusion 26 extending in the other axial direction is formed at the other circumferential and radially outer corner of the other axial side surface of each of the two locked protrusions 24. A ring-shaped locking groove 28 is formed in the other axial end of the inner peripheral surface of the one-side outer peripheral wall 18.

[0014] The other housing body 14 is composed of a circular other end plate 30 arranged perpendicular to the axial direction and a cylindrical other outer peripheral wall 32 extending axially from the outer periphery of the other end plate 30. The outer diameter of the other end plate 30 is substantially the same as the outer diameter of the one end plate 16. A circular through-hole 34 is also formed in the center of the other end plate 30, penetrating in the axial direction. The outer diameter of one axial end of the other outer peripheral wall 32 is slightly reduced, and a ring-shaped locking ridge 36 is provided on the outer peripheral surface. The locking ridge 36 is elastically locked into the locking groove 28 of the one housing body 12, allowing the other housing body 14 to be assembled to the one housing body 12.

[0015] The actuating plate 6 is rotatable around the rotation axis o relative to the housing 4 within a predetermined angular range. Referring to FIG. 4 along with FIGS. 1 and 2, the actuating plate 6, which is made of synthetic resin, includes a circular base 38 arranged perpendicular to the axial direction and a fan-shaped other-side support protrusion 40 formed by locally increasing the outer diameter of the base 38. In the illustrated embodiment, two other-side support protrusions 40 are formed at equal angular intervals in the circumferential direction. When the actuating plate 6 and the one-side housing body 12 are combined, the two other-side support protrusions 40 and the two one-side support protrusions 26 are aligned in the axial direction, and as shown in the CC cross-sectional view of FIG. 1, each of the two other-side support protrusions 40 is disposed between two one-side support protrusions 26. One circumferential side surface of one of the two other-side support projections 40 faces the other circumferential side surface of one of the two one-side support projections 26 in the circumferential direction, and the other circumferential side surface of one of the two other-side support projections 40 faces the other circumferential side surface of the other of the two one-side support projections 26 in the circumferential direction, via the compression coil spring 8. Also, one circumferential side surface of the other of the two other-side support projections 40 faces the other circumferential side surface of the other of the two one-side support projections 26 in the circumferential direction, and the other circumferential side surface of the other of the two other-side support projections 40 faces the one circumferential side surface of one of the two one-side support projections 26 in the circumferential direction, via the compression coil spring 8. Therefore, both ends of the compression coil spring 8 are supported by one circumferential side surface of the one-side support projection 26 and the other circumferential side surface of the other-side support projection 40. In the illustrated embodiment, the one-side support protrusion 26, the other-side support protrusion 40, and the compression coil spring 8 are arranged one on each side in the diametric direction. On the other axial side of the actuating plate 6, a substantially rectangular engaging recess 42 is formed over the entire radial length of the base 38 or at the radially inner end of each of the two other-side support protrusions 40. Therefore, two engaging recesses 42 are formed, and the two engaging recesses 42 are arranged on both sides in the diametric direction. A fan-shaped locking protrusion 44 extending around the rotation axis o is also formed on one axial side of the actuating plate 6. One locking protrusion 44 is provided corresponding to each of the two other-side support protrusions 40. Therefore, there are two locking protrusions 44.When viewed in the axial direction, the outer peripheral edges and one circumferential side edges of each of the two locking protrusions 44 and the two other-side support protrusions 40 are aligned, and the other circumferential side edges of each of the two locking protrusions 44 are slightly displaced toward the other circumferential side relative to the other circumferential side edges of each of the two other-side support protrusions 40. In other words, the locking protrusions 44 have a longer circumferential length than the other-side support protrusions 40. Furthermore, the inner peripheral edges of each of the two locking protrusions 44 are aligned with the inner peripheral edge of the base 38. When the actuation plate 6 and the housing half 12 are assembled, as shown in the B-B cross-sectional view of FIG. 1 , each of the two locking protrusions 44 is fitted into one of two locking recesses 22 formed in the end plate 16 of the housing half 12. As shown in the same figure, the locking protrusions 44 have a shorter circumferential length than the locking recesses 22. In the illustrated embodiment, the range of movement of the housing 4 relative to the actuating plate 6, i.e., the above-mentioned predetermined angular range, is defined by the locking recess 22 and the locking protrusion 44. When the actuating plate 6 rotates around the rotation axis o relative to the housing 4, a relatively small repulsive torque is generated due to the presence of the compression coil spring 8.

[0016] Torque limiter 10 includes a first member and a second member that are rotatable relative to each other around rotation axis o, and a connecting member that connects the first member and the second member with a relatively large resistance torque. Torque limiter 10 itself is a well-known mechanical component, and the first member, second member, and connecting member may have any configuration. Referring to FIG. 1 , in the illustrated embodiment, a first member designated by numeral 46 has a cylindrical inner circumferential surface, and a second member designated by numeral 48 has a cylindrical outer circumferential surface, with the inner circumferential surface of first member 46 facing the outer circumferential surface of second member 48 (therefore, first member 46 corresponds to a so-called outer ring, and second member 48 corresponds to a so-called inner ring). The connecting member designated by numeral 50 is a torsion coil spring that includes a winding portion 52 around which a wire is wound and single hook portions 54 provided at both ends of the winding portion 52. The inner diameter of the wound portion 52 in a free state is smaller than the outer diameter of the second member 48, and the wound portion 52 is attached to the outer peripheral surface of the second member 48 in a state in which it is slightly expanded in diameter. The hook portion 54 is inserted into a hook groove 56 formed in the inner peripheral surface of the first member 46, and when the first member 46 and the second member 48 rotate relatively in a predetermined direction around the rotation axis o (the first member 46 rotates to one side in the circumferential direction relative to the second member 48), the hook portion 54 is pressed by the first member 46 in the hook groove 56 in a direction that weakens the tightening of the torsion coil spring, which is the connecting member 50. Two engaging protrusions 58 that protrude to one side in the axial direction are formed on one axial end face of the first member 46, and each of the two engaging protrusions 58 is engaged, one by one, with each of two engaging recesses 42 formed on the other axial side face of the operating plate 6, thereby connecting the first member 46 to the operating plate 6. Although not necessarily clearly shown, two notches 60 are formed in the other axial end surface of the second member 48, and each of the two notches 60 is connected to a fixing means (not shown). Thus, the second member 48 is fixed. If desired, the first member 46 may be connected to a fixing means to connect the second member 48 to the operating plate 6. The other axial end of the first member 46 is closed by a shield member 62.

[0017] Next, the operation of the rotation resistance device 2 will be described with reference to Figures 1 and 5. As described above, the housing 4 is fixed to a rotating body (not shown) and rotates integrally with this rotating body around the rotation axis o.

[0018] Fig. 1 shows a state in which the rotating body, i.e., the housing 4, is stationary. In this state, the operating plate 6 is held in place by the resistance torque of the connecting member 50 of the torque limiter 10. The housing 4 is urged toward the other circumferential direction relative to the operating plate 6 by the spring force of the compression coil spring 8, and as shown in the CC cross-sectional view of Fig. 1, the other circumferential side surfaces of the two one-side support protrusions 26 are brought into contact with one circumferential side surfaces of the two other-side support protrusions 40, and as shown in the BB cross-sectional view of Fig. 1, the other circumferential side surfaces of the two locked protrusions 24 are brought into contact with one circumferential side surfaces of the two locking protrusions 44.

[0019] When a driving torque is applied to the rotor from the state shown in FIG. 1 and the rotor rotates in one circumferential direction, the housing 4 is also rotated in one circumferential direction. This rotation of the housing 4 in one circumferential direction also rotates the one-side support protrusion 26 in one circumferential direction, and the one-side support protrusion 26 presses the other-side support protrusion 40 of the actuating plate 6 in one circumferential direction via the compression coil spring 8. As described above, the resistance torque of the connecting member 50 of the torque limiter 10 is greater than the repulsive torque of the compression coil spring 8. Therefore, the actuating plate 6 is held in place by the resistance torque without being rotated in one circumferential direction by the compression coil spring 8. Therefore, as shown in the CC cross-sectional view of FIG. 5, the one-side support protrusion 26 rotates in one circumferential direction relative to the actuating plate 6 while compressing the compression coil spring 8, i.e., against the spring force of the compression coil spring 8. At this time, the locking recess 22 of the housing 4 also rotates in one circumferential direction relative to the locking protrusion 44 of the actuating plate 6. Then, when the housing 4 rotates circumferentially to one side by a predetermined angle, as shown in the B-B cross-sectional view of Figure 5, the other circumferential end face of the locking recess 22, i.e., the one circumferential end face of the locked protrusion 24, abuts against the other circumferential end face of the locking protrusion 44, and thereafter the one circumferential end face of the locked protrusion 24 presses the other circumferential end face of the locking protrusion 44 to one circumferential side, and the housing 4 rotates to one circumferential side together with the operating plate 6. The first member 46 of the torque limiter 10 is connected to the operating plate 6, and the second member 48 is fixed, so when the first member 46 connected to the operating plate 6 rotates in one circumferential direction relative to the second member 48, the hook portion 54 of the connecting member 50 is pressed by the first member 46 in the hook groove 56 in a direction that loosens the tightening of the torsion coil spring, and the housing 4, operating plate 6, and first member 46 of the torque limiter 10 together with the rotor are rotated in one circumferential direction against the relatively large resistance torque. Then, when the driving torque applied to the rotor is released, the operating plate 6 and first member 46 are held in place by the relatively large resistance torque of the connecting member 50 of the torque limiter 10, and the housing 4 and rotor are rotated in the other circumferential direction relative to the operating plate 6 due to the relatively small repulsive torque of the compression coil spring, returning to the state shown in FIG. 1.

[0020] Therefore, in the rotation resistance device constructed according to the present invention, when a driving torque is applied to the rotor to rotate it in one direction, the operating plate 6 is initially held by the resistance torque of the connecting member 50 of the torque limiter 10, and the housing 4 is caused to rotate in one direction relative to the operating plate 6 against the spring force of the compression coil spring 8. At this time, the resistance torque of the connecting member 50 is greater than the repulsive torque of the compression coil spring 8, so the operating plate 6 is securely held by the resistance torque. After the housing 4 has rotated a predetermined angle, the housing 4 is caused to rotate in one direction together with the operating plate 6 against the resistance torque. Then, when the driving torque applied to the rotor is released, that is, when the driving torque applied to the rotor is released, the operating plate 6 is held by the relatively large resistance torque of the connecting member 50 of the torque limiter 10, and the housing 4 is caused to rotate in the opposite direction relative to the operating plate 6 by the relatively small repulsive torque of the compression coil spring 8. The distance by which the housing 4 is rotated in the opposite direction can be adjusted as needed by adjusting the length of the compression coil spring 8, etc. Therefore, according to the present invention, a rotation resistance device is provided in which, when the driven rotation of the rotor in one direction is terminated, the rotor is caused to rotate sufficiently back in the opposite direction. While it is possible to use other spring means such as a torsion coil spring instead of the compression coil spring 8, torsion coil springs are far less durable than compression coil springs. This is because the load is concentrated on the hook portion of a torsion coil spring.

[0021] In the illustrated embodiment, one end plate 16 of the housing 4 is formed with a sector-shaped locking recess 22 extending around the rotation axis o, and the actuating plate 6 is formed with a sector-shaped locking protrusion 44 extending around the rotation axis o, the circumferential length of the locking protrusion 44 being shorter than the circumferential length of the locking recess 22, the locking protrusion 44 being fitted into the locking recess 22, and when the housing 4 rotates beyond the above-mentioned predetermined angle range with respect to the actuating plate 6, the locking protrusion 44 is pressed relatively by the housing 4. Therefore, by appropriately adjusting the circumferential length of the locking protrusion 44 relative to the locking recess 22, it is possible to adjust the distance by which the housing 4 is rotated in the opposite direction when the driven rotation of the rotor has finished. Furthermore, since the locking recess 22 and the locking protrusion 44 are arranged one on each side in the diametric direction, and since the one-side support protrusion 26, the other-side support protrusion 40, and the compression coil spring 8 are arranged one on each side in the diametric direction, the housing 4 can press the operating plate 6 in a balanced manner, and the housing 4 can rotate stably.

[0022] Although the rotation resistance device constructed according to the present invention has been described in detail above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiment, and appropriate modifications and variations are possible without departing from the scope of the present invention. For example, in the illustrated embodiment, two locking recesses 22 and two locking protrusions 44, two one-side support protrusions 26 and two other-side support protrusions 40, and two compression coil springs 8 are provided, but one of each may be provided, or three or more may be provided. When three or more are provided, it is preferable that they are disposed at equal angular intervals in the circumferential direction. Furthermore, the locking recess 22 (locked protrusion 24) and the locking protrusion 44 are not necessarily required. They may be omitted, and the one-side support protrusion 26 may press the other-side support protrusion 40 in the circumferential direction via the compression coil spring 8. However, having the locked protrusion 24 press the locking protrusion 44 in the circumferential direction is preferable because (1) the repulsive load of the compression coil spring 8 is constant, stabilizing the transmitted drive, and (2) the amount of rotation of the housing in the opposite direction caused by the compression coil spring is constant, stabilizing operation. As described above, the torque limiter 10 may be of any type, and may be a one-way torque limiter or a bidirectional torque limiter. The connecting member 50 is also not limited to a torsion coil spring, but may be a leaf spring, a tolerance ring, a so-called ring spring, or the like. The rotation resistance device constructed according to the present invention is applicable not only to hot printers but also to various other mechanical devices. [Explanation of symbols]

[0023] 2:Rotational resistance device 4: Housing 6: Operating plate 8: Compression coil spring 10: Torque limiter 46: First member 48: Second member 50: Connection member o: Rotation axis of the rotating body

Claims

1. In a rotation resistance device that applies resistance to a rotating body, The torque limiter includes a housing rotatable about a common rotation axis, and an operating plate, a compression coil spring, and a torque limiter housed in the housing, the actuation plate is rotatable around the rotation axis relative to the housing within a predetermined angle range; the compression coil spring is disposed between the actuation plate and the housing and generates a relatively small repulsive torque when the housing rotates relative to the actuation plate; a torque limiter including a first member and a second member that are rotatable relative to each other around the rotation axis, and a connecting member that connects the first member and the second member with a relatively large resistance torque, wherein one of the first member and the second member is connected to the operating plate, and the other is connected to a fixing means.

2. 2. The rotation resistance device according to claim 1, wherein the housing has an end plate arranged perpendicular to the rotation shaft, the end plate having a sector-shaped locking recess extending around the rotation shaft, and the actuation plate having a sector-shaped locking protrusion extending around the rotation shaft, the circumferential length of the locking protrusion being shorter than the circumferential length of the locking recess, the locking protrusion being fitted into the locking recess, and the locking protrusion being pressed relatively by the housing in the locking recess.

3. The rotation resistance device according to claim 2 , wherein the locking recess and the locking protrusion are both disposed one on each side in the diametrical direction.

4. The housing has an end plate disposed perpendicular to the rotation shaft, and the end plate is formed with a one-side support protrusion protruding in the axial direction, the actuation plate includes a base portion disposed perpendicular to the rotation shaft and a support protrusion on the other side formed by locally increasing the outer diameter of the base portion, 2. The rotation resistance device according to claim 1, wherein both ends of said compression coil spring are supported by one circumferential side surface of said one-side support protrusion and the other circumferential side surface of said other-side support protrusion.

5. 5. The rotation resistance device according to claim 4, wherein the one-side support protrusion, the other-side support protrusion, and the compression coil spring are arranged one on each side in the diametrical direction.

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