Tonearm lateral rotation braking device

Abstract

To brake the lateral rotation of a tone arm which holds a cartridge for reading information from a disc record having a sound groove engraved on the surface via a needle or a cantilever to improve the degree of sound reproduction.SOLUTION: A ferromagnet 20 with a discs-like shape orthogonal to a rotation shaft 9 of a tone arm 5 is fixed to the rotation shaft 9. A magnet block 21 formed by arranging a plurality of magnets in such a manner that N poles and S poles of the magnets are alternately arrayed on a concentric circle of the rotation shaft 9, is provided on a plane oppositely adjacent to the ferromagnet 20 in the axial direction of the rotation shaft 9. The rotation of the ferromagnet 20 which rotates following the rotation of the tone arm 5 is braked by a magnetic friction force caused by magnetic hysteresis, thereby preventing a decrease in the degree of sound reproduction as a result of lateral rotation of the tone arm 5 caused by the movement of a cantilever 8.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a horizontal rotation braking device for a tone arm, and more particularly to a horizontal rotation braking device that applies a braking force to undesirable horizontal rotation of the tone arm in a playback device to improve the sound reproduction quality.

Background Art

[0002] Conventionally, playback devices such as record players for playing back information such as music from a record turntable have been widely used in practical applications. In such a playback device, in many cases, a cartridge holding a cantilever with a needle fixed to follow the sound groove of the record turntable is used for information playback. And that cartridge is generally held by a tone arm and used. The cantilever transmits the movement of the needle corresponding to the shape of the sound groove of the record turntable to a power generation mechanism, and thereby a playback signal of a voltage corresponding to the shape of the sound groove, that is, the recorded information, is obtained from the power generation mechanism.

[0003] Therefore, in order to obtain a playback signal for accurately playing back the recorded information, it is necessary that the movement of the cantilever be accurately transmitted to the power generation mechanism. However, according to the research of the present inventor, it has been found that a part of the movement of the cantilever acts in the direction of horizontally rotating the tone arm, and for this reason, the accuracy of the playback signal may be impaired. The above-mentioned horizontal rotation means rotation centered on the rotation axis of the tone arm parallel to the rotation axis of the record turntable that is rotated for information playback. In order to prevent this problem, it is conceivable to apply a certain braking force to the tone arm so that the tone arm does not move in the direction of horizontal rotation by the degree of movement of the cantilever and only allows the movement of the cantilever that follows the sound groove.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention aims to provide a tonearm lateral rotation braking device that can brake the undesirable lateral rotation of the tonearm of a playback device, thereby improving sound reproduction accuracy and realizing a high-performance playback device. [Means for solving the problem]

[0005] The first tonearm lateral rotation brake device according to the present invention is A braking device that applies a force to a tonearm, which holds a cartridge that reads information from a record disc with grooves engraved on its surface via a needle and cantilever, to prevent lateral rotation. A rotating shaft that holds the tonearm and is capable of rotating laterally integrally with the tonearm, A ferromagnetic material having one surface perpendicular to the axis of rotation and fixed to the axis of rotation, A magnet block comprising a ferromagnetic material having adjacent and opposing surfaces on one surface in the direction of the rotation axis, wherein a plurality of magnets are fixed on the surface in a state where the north poles and south poles are alternately arranged on concentric circles of the rotation axis, and a magnet block fixed at a distance from the rotation axis so as to surround the rotation axis, at a position where magnetic force can act on the ferromagnetic material without mechanical interference, It is equipped with the following features.

[0006] Preferably, the ferromagnetic material described above is a disc-shaped ferromagnetic material fixed to the rotation axis so as to be perpendicular to the rotation axis. Furthermore, both permanent magnets and electromagnets can be used. The shape of each magnet is not limited to a specific shape; round magnets, or a circular arrangement where the magnets are close together at the center and gradually widen towards the outside of the circle (a sector shape with a small central angle), can be used as appropriate. The magnet block may be positioned to face the ferromagnetic material not only from one side of the ferromagnetic material, but also from both sides. Furthermore, the ferromagnetic material may be positioned to face the magnet block from both sides of the magnet block. In other words, multiple sets of ferromagnetic material and magnet block pairs adjacent in the axial direction of the rotation axis may be provided along the axial direction. The same applies to the lateral rotation brake device of the second tonearm described below.

[0007] Furthermore, the lateral rotation brake device for the second tonearm according to the present invention is A braking device that applies a force to a tonearm, which holds a cartridge that reads information from a record disc with grooves engraved on its surface via a needle and cantilever, to prevent lateral rotation. A rotating shaft that holds the tonearm and is capable of rotating laterally integrally with the tonearm, A magnet block fixed to the rotation axis, wherein multiple magnets are fixed in a state where the north poles and south poles are alternately arranged on concentric circles on a plane perpendicular to the rotation axis, A ferromagnetic material is disposed at a predetermined position spaced away from the rotation axis, in a position where the magnetic force from the magnet block can act without mechanical interference with the magnet block, with one surface oriented perpendicular to the rotation axis and the other surface adjacent to and facing the rotation axis in the axial direction of the magnet block and the rotation axis, thereby surrounding the rotation axis. It is equipped with the following features.

[0008] In the first and second tonearm lateral rotation brake devices according to the present invention, it is desirable that the magnetic block is made up of a plurality of magnets, with north poles and south poles aligned in the axial direction of the rotation axis, embedded in a support, for example, an annular shape, centered on a hole surrounding the rotation axis, such that the north poles and south poles alternate at equal intervals in concentric circles on the side facing the ferromagnetic material. The distance between the north poles and south poles is preferably about 1 mm or less, as an example. The smaller this distance, the stronger the magnetic hysteresis braking force described below can be made. In the first tonearm lateral rotation brake device according to the present invention described above, the hole is naturally sized to create an air gap between it and the rotation axis, while in the other tonearm lateral rotation brake device according to the present invention described above, it is generally sized to fit onto the rotation axis.

[0009] Furthermore, the third tonearm lateral rotation brake device according to the present invention is A braking device that applies a force to a tonearm, which holds a cartridge that reads information from a record disc with grooves engraved on its surface via a needle and cantilever, to prevent lateral rotation. A rotating shaft that holds the tonearm and is capable of rotating laterally integrally with the tonearm, A ferromagnetic material having an outer surface concentric with the axis of rotation and fixed to the axis of rotation, A magnet block comprising a plurality of magnets adjacent to and facing each other from the radially outer surface of the ferromagnetic material, fixed in a state where the north poles and south poles are alternately arranged on the concentric circles of the rotation axis, wherein the magnet block is positioned so that magnetic force can act on the ferromagnetic material without mechanical interference, It is equipped with the following features.

[0010] Furthermore, the fourth tonearm lateral rotation brake device according to the present invention is A braking device that applies a force to a tonearm, which holds a cartridge that reads information from a record disc with grooves engraved on its surface via a needle and cantilever, to prevent lateral rotation. A rotating shaft that holds the tonearm and is capable of rotating laterally integrally with the tonearm, A magnetic block fixed to this rotating shaft, wherein multiple magnets are fixed in a state where north poles and south poles are alternately arranged on concentric circles of the rotating shaft, A ferromagnetic material is provided in a position where the magnetic force from the magnet block can act on the magnet block without mechanical interference, such that its inner surface is concentric with the rotation axis and faces the plurality of magnets adjacent to them from the outer diameter of the rotation axis. It is equipped with the following features.

[0011] Furthermore, the fifth tonearm lateral rotation brake device according to the present invention is A braking device that applies a force to a tonearm, which holds a cartridge that reads information from a record disc with grooves engraved on its surface via a needle and cantilever, to prevent lateral rotation. A rotating shaft that holds the tonearm and is capable of rotating laterally integrally with the tonearm, A ferromagnetic material having an outer surface concentric with the axis of rotation and fixed away from the axis of rotation, A magnet block comprising a plurality of magnets adjacent to and facing each other from the radially outer surface of the ferromagnetic material, fixed on the rotation axis in a state where the north poles and south poles are alternately arranged on the concentric circle of the rotation axis, wherein the magnet block is fixed to the rotation axis at a position where magnetic force can act without mechanical interference with the ferromagnetic material, It is equipped with the following features.

[0012] Furthermore, the sixth tonearm lateral rotation brake device according to the present invention is A braking device that applies a force to a tonearm, which holds a cartridge that reads information from a record disc with grooves engraved on its surface via a needle and cantilever, to prevent lateral rotation. A rotating shaft that holds the tonearm and is capable of rotating laterally integrally with the tonearm, A magnetic block fixed away from this axis of rotation, wherein multiple magnets are fixed in a state where north poles and south poles are alternately arranged on concentric circles of the axis of rotation, It is fixed to the rotating shaft at a position where the magnetic force from the magnet block can act without mechanically interfering with the magnet block, and a ferromagnetic body is arranged such that an inner peripheral surface concentric with the rotating shaft faces the plurality of magnets adjacent to the outside of the diameter of the rotating shaft. It comprises the following.

[0013] In the horizontal rotation brake device for the 3rd to 6th tone arms according to the present invention described above, It is desirable to provide a plurality of sets of the ferromagnetic body and the magnet block adjacent to each other in the radial direction of the rotating shaft over the axial direction of the rotating shaft.

Effect of the Invention

[0014] In the horizontal rotation brake device for the 1st and 2nd tone arms according to the present invention, since the disk-shaped ferromagnetic body and the magnet block are arranged adjacent to each other in the direction in which the rotating shaft of the tone arm extends, when the rotating shaft tries to rotate, a magnetic hysteresis braking force (magnetic frictional force) acts between the ferromagnetic body and the magnet block, and a force for braking the horizontal rotation can be applied to the rotating shaft, that is, to the tone arm. And since the ferromagnetic body and the magnet block are arranged adjacent to each other in the direction in which the rotating shaft extends, the horizontal rotation brake device for the 1st and 2nd tone arms according to the present invention is compactly configured around the axis of the tone arm, so that it can be formed in a small size as a device without requiring space in the horizontal direction.

[0015] On the other hand, the horizontal rotation brake device for the 3rd to 6th tone arms according to the present invention arranges the ferromagnetic body and the magnet block as described above adjacent to each other in the radial direction of the rotating shaft. Even in this case, since a magnetic hysteresis braking force acts between the ferromagnetic body and the magnet block, a force for braking the horizontal rotation can be applied to the tone arm.

[0016] Note that as the record turntable rotates, the lateral rotation of the tone arm caused by the needle at the tip of the tone arm moving in the radial direction of the record turntable along the sound groove of the record turntable is extremely slow and incremental even when the position of the needle approaches the center of the record turntable, so the brake by magnetic friction hardly has an impact.

Brief Explanation of Drawings

[0017] [Figure 1] Schematic side view showing the lateral rotation brake device of the tone arm according to the first embodiment of the present invention [Figure 2] Plan view showing a part of the lateral rotation brake device of the tone arm [Figure 3] Schematic side view showing the lateral rotation brake device of the tone arm according to the second embodiment of the present invention [Figure 4] Schematic side view showing the lateral rotation brake device of the tone arm according to the third embodiment of the present invention [Figure 5] Plan view showing a part of the lateral rotation brake device of the tone arm shown in FIG. 4 [Figure 6] Schematic side view showing the lateral rotation brake device of the tone arm according to the fourth embodiment of the present invention [Figure 7] Plan view showing a part of the lateral rotation brake device of the tone arm shown in FIG. 6 [Figure 8] Schematic side view showing the lateral rotation brake device of the tone arm according to the fifth embodiment of the present invention

Modes for Carrying Out the Invention

[0018] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic side view showing the configuration of a tonearm lateral rotation brake device (hereinafter simply referred to as the lateral rotation brake device) 1 according to the first embodiment of the present invention. This lateral rotation brake device 1 is applied to a playback device 10 such as a record player that reproduces information such as music from a record 2, sometimes called an analog disc. First, the outline of this playback device 10 will be described. The playback device 10 has a turntable 3 that is rotated around a central axis C1 by a driving means (not shown). A spindle 4 is provided protruding from the upper surface of the turntable 3, coaxial with the central axis C1.

[0019] When playing music or other information from record 2, the record 2 is placed on the top surface of the turntable 3 with the spindle 4 inserted through a through-hole in its center. In most cases, the record 2 has two sides, known as "side A" and "side B," which are recording surfaces, but the record 2 is placed with the side to be played facing upwards.

[0020] For example, the tonearm 5, which is made of a hollow tubular member, holds the cartridge 6 at its tip, that is, the right end in the diagram. The cartridge 6 holds a cantilever 8 to which the stylus 7 is fixed. The tonearm 5 is held at the upper end of a vertically extending rotating shaft 9, near its base, that is, near the left end in the diagram. A balance weight 11 is also attached to the base of the tonearm 5 to adjust the tracking force, that is, the pressure of the stylus 7 on the record 2.

[0021] The rotating shaft 9 is rotatably held by a cylindrical holding member 13, which is fixed on a base 12 fixed to the bottom of the regeneration device 10, via a pair of upper and lower bearings 14, 14. The lower end of the rotating shaft 9 is also held on the base 12 so as to rotate smoothly via a thrust bearing 15.

[0022] The tonearm 5 is held on the rotation axis 9 via a support mechanism 16. In many conventional tonearms 5, a gimbal mechanism or the like is applied to this support mechanism 16, allowing the tonearm 5 to rotate relative to the rotation axis 9 in the directions of arrow A and arrow B (around the long axis C2 of the rotation axis 9). However, in this embodiment, relative rotation in the direction of arrow B is not possible. In other words, when the tonearm 5 rotates in the direction of arrow B, the rotation axis 9 rotates integrally with it. This rotation of the tonearm 5 in the direction of arrow B, that is, rotation around the rotation axis of the tonearm which is parallel to the rotation axis of the turntable 3 that rotates the record 2, is referred to as lateral rotation in this disclosure.

[0023] When playing music or other information from a record 2 placed on the top surface of the turntable 3, as shown in Figure 1, the needle 7 is slowly dropped onto the surface of the record 2, or more specifically, into the groove engraved on this surface, and the turntable 3 rotates in this state. As the record 2 rotates, the needle 7 moves according to the shape of the groove, and this movement is transmitted via the cantilever 8 to the power generation mechanism in the cartridge 6. From this power generation mechanism, a voltage signal corresponding to the shape of the groove, that is, corresponding to the recorded information, is obtained.

[0024] As is well known, the groove engraved on the record 2 is a single spiral groove that runs between the inner and outer edges of the record 2. Therefore, when information is continuously reproduced from the record 2, the tonearm 5 rotates laterally in response to the movement of the needle 7 along the groove. On the other hand, the movement of the cantilever 8 also corresponds to the movement of the needle 7 along the groove, and therefore includes a radial component of the record on the surface of the record 2. This movement of the cantilever 8 can cause the tonearm 5 to rotate laterally. However, if the tonearm 5 actually rotates laterally in this way, the movement of the cantilever 8, which should ideally all be converted into the aforementioned voltage signal, is also used for the lateral rotation of the tonearm 5, thus impairing the reproduction accuracy of the recorded information.

[0025] The lateral rotation brake device 1 is provided to prevent the occurrence of the above-mentioned malfunction. The lateral rotation brake device 1 will be described in detail below. In this embodiment, the lateral rotation brake device 1 is configured to include, in addition to the rotation shaft 9 described above, a disc-shaped ferromagnetic body 20 fixed to the rotation shaft 9 so as to be perpendicular to the rotation shaft 9, and a magnet block 21 fixed to a holding member 13 also provided at a predetermined position within the device. The ferromagnetic body 20 is formed in a disc shape using ferrite as an example.

[0026] On the other hand, the magnet block 21, as shown in Figure 2, has a planar shape in which a plurality of permanent magnets 23 are preferably embedded and fixed in an annular support 22. The support 22 has a circular hole 22a that penetrates through its center, and its outer surface 22b is circular and coaxial with the circular hole 22a. As an example, eight permanent magnets 23 are fixed in such a state that their upper end surfaces, which face the lower surface of the ferromagnetic material 20, are flush with each other, and their north and south poles alternate along the concentric circle of the rotation axis 9. The magnet block 21 is attached to the regeneration device 10 by fixing the outer surface 22b of the support 22 to the holding member 13, with the rotation axis 9 inserted through the circular hole 22a of the support 22.

[0027] Furthermore, when the magnetic block 21 is attached to the playback device 10 in this manner, the magnetic block 21 does not mechanically interfere with the ferromagnetic material 20, allowing the ferromagnetic material 20 to rotate together with the rotation axis 9. In this state, the magnetic force from each permanent magnet 23 of the magnetic block 21 can act on the ferromagnetic material 20.

[0028] In the playback device 10 with the above configuration, when the tonearm 5 rotates laterally, the ferromagnetic body 20, which is integrated with the tonearm 5 via the rotation axis 9, also rotates. The ferromagnetic body 20, which is positioned facing the magnet block 21, is magnetized by the magnet block 21, but as the ferromagnetic body 20 rotates, the magnetization direction of each magnetized part reverses in accordance with the magnetic poles of the eight permanent magnets 23. As a result, a magnetic friction force (hysteresis braking force) acts on the ferromagnetic body 20, and the lateral rotation of the rotation axis 9 and the tonearm 5 is braked. In this way, the lateral rotation of the tonearm 5 due to the movement of the cantilever 8 is suppressed, and only the lateral movement of the cantilever 8 following the sound groove is permitted. In other words, the movement of the cantilever 8 is used basically only for the aforementioned power generation without causing the tonearm 5 to rotate laterally, thus improving the accuracy of information reproduction. In addition, the lateral rotation braking device 1 also suppresses unwanted vibrations of the tonearm 5, which also improves the accuracy of information reproduction.

[0029] Conversely to this embodiment, even if the magnetic block 21 is fixed to the rotating shaft 9 and the ferromagnetic material 20 is fixed to the main body of the playback device 10, the lateral rotation of the tonearm 5 can still be damped in the same manner as described above. In other words, depending on the type of ferromagnetic material selected, patterns that are lighter or heavier than the magnet are possible. Also, depending on the installation of magnetic shielding to prevent magnetic field lines from escaping, it may be possible to change which is better to use as the magnet from a design perspective. Furthermore, it is also possible to fix the magnetic block to the tonearm side based on the idea that a heavier tonearm is better.

[0030] Next, with reference to Figure 3, a lateral rotation brake device 31 according to a second embodiment of the present invention will be described. In Figure 3, elements equivalent to those in Figures 1 and 2 described earlier are given the same numbers, and their explanations will be omitted unless particularly necessary (the same applies hereafter). The lateral rotation brake device 31, whose schematic side shape is shown in Figure 3, is applied to a regeneration device 30 similar to the regeneration device 10 described above.

[0031] The lateral rotation brake device 31 of this embodiment differs from the lateral rotation brake device 1 shown in Figure 1 in that it has two sets of ferromagnetic material 20 and magnet block 21 arranged in the axial direction. By providing multiple sets of ferromagnetic material 20 and magnet block 21 in this way, a stronger braking force can be generated compared to the case where only one set is provided.

[0032] In this embodiment, two sets of one ferromagnetic material 20 and one magnet block 21 are provided. However, it is also possible to configure two sets of ferromagnetic material 20 and magnet block 21 by arranging two magnet blocks 21 so that one ferromagnetic material 20 is sandwiched from above and below. Conversely, it is also possible to configure two sets of ferromagnetic material 20 and magnet block 21 by arranging two ferromagnetic material 20 so that one magnet block 21 is sandwiched from above and below. Such configurations can be appropriately adopted even when three or more sets of ferromagnetic material 20 and magnet block 21 are provided.

[0033] Next, with reference to Figure 4, a lateral rotation brake device 41 according to a third embodiment of the present invention will be described. The lateral rotation brake device 41, whose schematic side shape is shown in Figure 4, is applied to a regeneration device 40 similar to the regeneration device 10 described above. In the first and second embodiments, the ferromagnetic material 20 and the magnet block 21 are arranged facing each other in the axial direction of the rotation shaft 9, whereas the lateral rotation brake device 41 of this embodiment is fundamentally different in that the ferromagnetic material and the magnet block are arranged facing each other in the radial direction of the rotation shaft 9.

[0034] In other words, in the lateral rotation brake device 41 of this embodiment, a ferromagnetic material 50 similar to the ferromagnetic material 20 described above is fixed to the rotating shaft 9, and a magnet block 51 is arranged so as to surround this ferromagnetic material 20 from the radially outer side of the rotating shaft 9. As shown in the plan view in Figure 5, the disc-shaped ferromagnetic material 50 has an outer peripheral surface 50a concentric with the rotating shaft 9, and as an example, 16 permanent magnets 53 are fixed to the magnet block 51 so as to surround this outer peripheral surface 50a. Each permanent magnet 53 is positioned such that one end is adjacent to and facing the outer peripheral surface 50a of the ferromagnetic material 50 from the radially outer side of the rotating shaft 9, and the other end is located further radially outward than this one end. The 16 permanent magnets 53 are fixed so that the north poles and south poles are alternately arranged on the one end side (i.e., on a concentric circle of the rotating shaft 9).

[0035] The magnet block 51, arranged as described above, does not mechanically interfere with the ferromagnetic material 50, allowing the ferromagnetic material 50 to rotate together with the rotation axis 9. In this state, the magnetic force from each permanent magnet 53 of the magnet block 51 can act on the ferromagnetic material 50.

[0036] When the tonearm 5 rotates laterally in the playback device 40, the ferromagnetic body 50, which is integrated with the tonearm 5 via the rotation axis 9, also rotates. The ferromagnetic body 50, which is positioned facing the magnet block 51, is magnetized by the magnet block 51, but as the ferromagnetic body 50 rotates, the magnetization direction of each magnetized part reverses in accordance with the magnetic poles of the 16 permanent magnets 53. As a result, a magnetic friction force (hysteresis braking force) acts on the ferromagnetic body 50, and the lateral rotation of the rotation axis 9 and the tonearm 5 is braked.

[0037] In this way, the tonearm 5 is prevented from rotating laterally due to the movement of the cantilever 8, and only the lateral movement of the cantilever 8 following the groove is permitted. In other words, the movement of the cantilever 8 is used basically only for the aforementioned power generation without rotating the tonearm 5 laterally, thus improving the accuracy of information reproduction. In addition, the lateral rotation brake device 41 also suppresses unwanted vibrations of the tonearm 5, which further improves the accuracy of information reproduction.

[0038] Conversely to this embodiment, even if the magnet block is fixed to the rotating shaft 9 and the ferromagnetic material is fixed to the main body of the playback device 40, the lateral rotation of the tonearm 5 can be controlled in the same manner as described above. In that case, the ferromagnetic material can be shaped to have an inner surface concentric with the rotating shaft 9, while the magnet block can be fixed with multiple permanent magnets arranged alternately with north and south poles along the inner surface of the ferromagnetic material.

[0039] Next, with reference to Figure 6, a lateral rotation brake device 61 according to the fourth embodiment of the present invention will be described. The lateral rotation brake device 61, whose schematic side shape is shown in Figure 6, is applied to a regeneration device 60 similar to the regeneration device 40 shown in Figure 4. Similar to the lateral rotation brake device 41 of the third embodiment applied to the regeneration device 40, the lateral rotation brake device 61 of this embodiment also has a ferromagnetic material and a magnet block arranged facing each other in the radial direction of the rotation axis 9. However, the third embodiment rotates the ferromagnetic material, while this embodiment rotates the magnet block, which is a fundamental difference.

[0040] In other words, in the lateral rotation brake device 61 of this embodiment, the center of a rotating connecting member 72, for example, is fixed to the rotating shaft 9, and a magnet block 71 is fixed to this rotating connecting member 72. As shown in the plan view in Figure 7, the magnet block 71, like the magnet block 51 shown in Figures 4 and 5, consists of, for example, 16 permanent magnets 73 fixed to it. On the other hand, the outer circumference of a stationary connecting member 74, for example, is fixed to a cylindrical holding member 13, and a ferromagnetic material 70, similar to the ferromagnetic material 50 shown in Figures 4 and 5, is fixed to this stationary connecting member 74, away from the rotating shaft 9.

[0041] Figure 7 shows the planar positional relationship between the ferromagnetic material 70 and the magnet block 71, omitting the rotating connecting member 72 and the stationary connecting member 74 described above. As shown in Figure 7, the annular ferromagnetic material 70 has an outer peripheral surface 70a concentric with the rotation axis 9, and the 16 permanent magnets 73 of the magnet block 71 are arranged such that one end faces adjacent to the outer peripheral surface 70a of the ferromagnetic material 70 from the radially outward side of the rotation axis 9, and the other end is located further radially outward than this one end. The 16 permanent magnets 73 are fixed so that the north poles and south poles are alternately arranged on the one end side (i.e., on a concentric circle of the rotation axis 9).

[0042] The magnet block 71, arranged as described above and fixed to the rotating shaft 9 via the rotating connecting member 72, can rotate together with the rotating shaft 9 without mechanically interfering with the ferromagnetic material 70. In this state, the magnetic force from each permanent magnet 73 of the magnet block 71 can act on the ferromagnetic material 70.

[0043] When the tonearm 5 rotates laterally in the playback device 60, the magnet block 71, which is integrated with the tonearm 5 via the rotation axis 9 and the rotation connecting member 72, also rotates. The ferromagnetic material 70, which is positioned opposite the magnet block 71, is magnetized by the magnet block 71, but as the magnet block 71 rotates, the magnetization direction of each magnetized portion reverses in accordance with the magnetic poles of the 16 permanent magnets 73. As a result, a magnetic friction force (hysteresis braking force) acts on the ferromagnetic material 70, and the lateral rotation of the rotation axis 9 and the tonearm 5 is braked. This improves the accuracy of information playback by the playback device 60, as in the third embodiment.

[0044] Conversely to this embodiment, even if the magnet block 71 is kept stationary while the ferromagnetic material 70 is made rotatable with the rotation shaft 9, the lateral rotation of the tonearm 5 can be braked in the same manner as described above. Figure 8 shows a schematic side view of the lateral rotation brake device 81 according to the fifth embodiment of the present invention, configured in this way and applied to the playback device 80. In Figure 8, the inner circumferential surface of the ferromagnetic material 70 is shown as 70b. [Explanation of symbols]

[0045] 1, 31, 41, 61, 81 Tonearm lateral rotation brake device 2 vinyl records 3 Turntables 4 spindles 5 Tonearm 6 cartridges 7 needles 8 Cantilever 9 Rotation axis 10, 30, 40, 60, 80 playback device 13 Retaining member 20, 50, 70 ferromagnetic material 21, 51, 71 Magnetic Blocks 22 Support 23, 53, 73 permanent magnets 50a, 70a Outer surface of ferromagnetic material 70b Inner surface of ferromagnetic material 72 Rotating connecting member 74 Static connecting member

Claims

1. A braking device that applies a force to a tonearm, which holds a cartridge that reads information from a record disc with grooves engraved on its surface via a needle and cantilever, to prevent lateral rotation. A rotating shaft that holds the tonearm and is capable of rotating laterally integrally with the tonearm, A ferromagnetic material having a plane perpendicular to the rotation axis and directly fixed to the rotation axis, A magnet block provided adjacent to the ferromagnetic material along the direction in which the rotation axis extends, having a surface facing the ferromagnetic material, on which a plurality of magnets are fixed in a state where N poles and S poles are alternately arranged in concentric circles of the rotation axis, and fixed at a distance from the rotation axis so as to surround the rotation axis, in a position where magnetic force can act on the ferromagnetic material without mechanical interference, A tonearm lateral rotation brake device equipped with the following.

2. A braking device that applies a force to a tonearm, which holds a cartridge that reads information from a record disc with grooves engraved on its surface via a needle and cantilever, to prevent lateral rotation. A rotating shaft that holds the tonearm and is capable of rotating laterally integrally with the tonearm, A ferromagnetic material having one surface perpendicular to the rotation axis and fixed to the rotation axis, A magnet block comprising a ferromagnetic material having adjacent and opposing surfaces on one surface in the direction of the rotation axis, wherein a plurality of magnets are fixed on the surface in a state where the north poles and south poles are alternately arranged on concentric circles of the rotation axis, and a magnet block fixed at a distance from the rotation axis so as to surround the rotation axis, at a position where magnetic force can act on the ferromagnetic material without mechanical interference, Equipped with, A tonearm lateral rotation brake device, wherein the ferromagnetic material is a disc-shaped ferromagnetic material fixed to the rotation axis so as to be perpendicular to the rotation axis.

3. A braking device that applies a force to a tonearm, which holds a cartridge that reads information from a record disc with grooves engraved on its surface via a needle and cantilever, to prevent lateral rotation. A rotating shaft that holds the tonearm and is capable of rotating laterally integrally with the tonearm, A magnet block fixed to the rotation axis, wherein multiple magnets are fixed in a state where the north poles and south poles are alternately arranged on concentric circles on a plane perpendicular to the rotation axis, A ferromagnetic material is disposed at a position where the magnetic force from the magnet block can act on the magnet block without mechanical interference, with one surface oriented parallel to the axis of rotation, and the one surface facing the magnet block and the axis of rotation adjacent to each other in the radial direction, and spaced apart from the axis of rotation, surrounding the axis of rotation. Equipped with, This system does not apply braking force to the rotating shaft using a viscous liquid sealed in a tightly sealed container. A lateral rotation braking device for the tonearm.

4. The tonearm lateral rotation brake device according to any one of claims 1 to 3, wherein the plurality of magnets in the magnet block are arranged with a distance of 1 mm or less between the north pole and the south pole.

5. A tonearm lateral rotation brake device according to any one of claims 1 to 4, wherein a plurality of sets of the ferromagnetic material and the magnet block, adjacent to each other in the axial direction of the rotation axis, are provided along the axial direction.

6. A braking device that applies a force to a tonearm, which holds a cartridge that reads information from a record disc with grooves engraved on its surface via a needle and cantilever, to prevent lateral rotation. A rotating shaft that holds the tonearm and is capable of rotating laterally integrally with the tonearm, A ferromagnetic material having an outer surface concentric with the rotation axis and fixed to the rotation axis, A magnet block comprising a plurality of magnets adjacent to and facing each other from the outer circumferential surface of the ferromagnetic material, fixed in a manner in which the north poles and south poles are alternately arranged on the concentric circle of the rotation axis, wherein the magnet block is positioned so that magnetic force can act on the ferromagnetic material without mechanical interference, Equipped with This system does not apply braking force to the rotating shaft using a viscous liquid sealed in a tightly sealed container. A lateral rotation braking device for the tonearm.

7. A braking device that applies a force to a tonearm, which holds a cartridge that reads information from a record disc with grooves engraved on its surface via a needle and cantilever, to prevent lateral rotation. A rotating shaft that holds the tonearm and is capable of rotating laterally integrally with the tonearm, A ferromagnetic material having an outer surface concentric with the rotation axis and fixed away from the rotation axis, A magnet block comprising a plurality of magnets adjacent to and facing each other from the outer circumferential surface of the ferromagnetic material, fixed on the rotation axis in a state where the north poles and south poles are alternately arranged on the rotation axis, wherein the magnet block is fixed to the rotation axis at a position where magnetic force can act on the ferromagnetic material without mechanical interference, A tonearm lateral rotation brake device equipped with the following.

8. A tonearm lateral rotation brake device according to claim 6 or 7, wherein a plurality of sets of the ferromagnetic material and the magnet block, adjacent to each other in the radial direction of the rotation axis, are provided along the axial direction of the rotation axis.

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