Joint structure between cantilever and stylus of cartridge

Abstract

To provide a joint structure between a cantilever and a stylus of a cartridge to solve the problems such as the cartridges for playing analog records need to transmit the displacement of the record groove picked up by the stylus to the cantilever without attenuation or absorption, recently, some cartridges have used hard materials such as diamond for the cantilever, but a resin-based adhesive has been required to join the stylus and cantilever, and because this resin-based adhesive exists between the stylus and the cantilever, the elasticity of the resin-based adhesive layer becomes an obstacle, making it difficult to accurately transmit the subtle displacement of the record groove to the cantilever.SOLUTION: In a joint structure between a stylus that follows record grooves and a cantilever that holds the stylus of a cartridge that extracts sound signals from a record, by using a resin mixed with hard powder as the resin used to join the stylus attached to the hole at the tip of the cantilever, it is possible to minimize the effects of the resin absorbing the displacement of the record grooves due to the mixed resin and to achieve good sound reproduction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a joint structure between a cantilever and a stylus in a cartridge used for playing analog records (hereinafter simply referred to as records). [Background technology]

[0002] To play a record, the record is placed on the turntable of the record player and a needle at the tip (hereafter referred to as a stylus) traces the signal grooves on the surface of the record, converting the changes in the record grooves into an electrical signal, which is then amplified and played through the speakers.

[0003] The part that converts the changes in the record groove into an electrical signal is usually called the cartridge. The cartridge is attached to a tone arm and is able to move in accordance with the grooves on the surface of the record.

[0004] The part of the cartridge that comes into contact with the record groove is a cylindrical or rod-shaped cantilever with a record needle called a stylus attached to the tip, which is held movable by a rubber damper in most cases. A tiny magnet or coil is attached to the other side of the cantilever's stylus, where the physical displacement of the record groove is electromagnetically converted to an electrical output.

[0005] Figure 2 shows an example of the structure of a so-called moving coil type cartridge, which generates electricity by moving a fine coil in a fixed magnetic field. The present invention can also be applied to electrostatic, photoelectric, and piezoelectric cartridges.

[0006] In the example shown in the figure, yokes 12 made of iron or the like are attached to both ends of a rod-shaped magnet 11, with the opposite ends of the yoke 12 facing each other, and a columnar metal member 13 protrudes from the end of one of the yokes 12 to form a gap 14. On the other hand, the cantilever 1 is made of a lightweight, rigid metal material such as aluminum alloy and is tubular in shape to reduce weight, and is held by a rubber damper 15 located at its end, with the tip flattened for attachment to the stylus 4 and angled to be nearly parallel to the record surface.

[0007] The stylus 4 is made of a hard material called a jewel, such as diamond, ruby, or sapphire, and has a convex tip that follows the grooves of a record. A hole is drilled in the flat surface at the tip of the cantilever 1, and the stylus 4 is attached by press-fitting, snapping, or adhesive.

[0008] The cantilever 1 is positioned so as to pass through a gap 14 in the yoke 12, and two sets of coils 17, made of thin wire wound vertically around a plate-like member 16, are formed at the position where the cantilever 1 passes through the gap 14. The displacement of the record groove picked up by the stylus 4 is followed by the cantilever 1, which moves around the rubber damper 15 as a fulcrum, and the coil 17 in the magnetic field also moves in response, generating an electromotive force. As two sets of coils 17 are formed vertically, a stereo signal from the record groove can be picked up.

[0009] As described above, the cantilever of the cartridge is generally made of a highly rigid and lightweight material such as an aluminum alloy in order to faithfully transmit minute changes in the record groove picked up by the stylus. The stylus is made of a hard material with high wear resistance because it comes into contact with the groove of the record and transmits the change in the groove to the cantilever. Generally, a precious stone such as diamond, ruby, or sapphire is polished into a small needle shape.

[0010] The cantilever and stylus are connected by bending the tip of the cylindrical cantilever so that it is nearly parallel to the record surface, forming a flat section, and drilling a hole in this flat section with a diameter smaller than that of the stylus, and then pressing and fitting the stylus into the hole to connect them. Generally, with this type of connection structure, the stylus is pressed in and held in place by the elasticity of the aluminum alloy metal, so there is no need to use adhesive at the joint. Therefore, the changes in the record groove picked up by the stylus are transmitted directly to the cantilever without passing through an adhesive layer.

[0011] In order to reproduce sound with higher fidelity, various considerations are being made regarding the material of the cantilever. Diamond is attracting attention as a lightweight and highly rigid material. With recent improvements in crystal growth technology, it is now possible to easily form diamonds in relatively large shapes.

[0012] If a crystal-grown material such as diamond is used for the cantilever of a cartridge, it is lightweight and highly rigid, so that the displacement of the record groove can be faithfully transmitted to the electrical conversion part, enabling highly accurate playback. Furthermore, one-piece diamond cantilevers have been proposed in recent years, in which the cantilever and stylus are formed as one unit and the tip of the stylus is polished. However, even though it has become easier to form them, it is not easy to manufacture a unit with a stylus and cantilever, and in addition to the difficulty of processing, the price is extremely high. Mass production is also difficult and impractical.

[0013] With metal materials such as aluminum alloys, the elasticity of the metal can be utilized to drill a hole slightly smaller than the diameter of the stylus and press the stylus into it to fit it in. However, when a hard material such as diamond is used for the cantilever, it is difficult to use a press-fit or fit connection method because the hard material has no elasticity, so it is necessary to drill a hole slightly larger in diameter than the stylus and inject adhesive into it to fix the stylus in place.

[0014] Epoxy resin adhesives are generally used as adhesives. Epoxy resins are widely used because the curing time can be controlled by selecting a curing assistant, they are easy to handle, and they have high strength after curing. However, in this bonding structure, a bonding resin layer is interposed between the stylus and the cantilever. For this reason, even if a material with high rigidity and hardness is used for the stylus and cantilever, the slight elasticity of the resin material means that the displacement of the record groove picked up by the stylus is not accurately transmitted to the cantilever, and high-fidelity sound reproduction is not possible. Summary of the Invention [Problem to be solved by the invention]

[0015] The object of this invention is to improve the sound quality of playback by improving the joint structure between the cantilever and stylus of a record playback cartridge. [Means for solving the problem]

[0016] The first invention is a joining structure between a stylus that follows the grooves of a record and a cantilever that holds the stylus, characterized in that the resin used to join the stylus attached to the hole at the tip of the cantilever is a resin mixed with a hard powder.

[0017] Next, in the second invention, the hard powder mixed into the resin used to bond the stylus attached to the hole at the tip of the cantilever is preferably one of diamond, ruby, sapphire, zirconia, boron, hard glass, or a mixture of these, and is preferably a material that does not impede the transmission of light. However, hard and inexpensive materials used in sandpaper can also be used, and are not limited to the above-mentioned materials.

[0018] A third aspect of the present invention is characterized in that the resin used to bond the cantilever to the stylus attached to the hole at the tip of the cantilever is an ultraviolet curing resin. Effect of the Invention According to this invention, a hard powder is mixed into the bonding resin that is interposed at the joint between the stylus and the cantilever of the cartridge, thereby improving the hardness of the bonding resin layer and reducing absorption of displacement from the stylus at the joint, allowing the displacement of the stylus to be faithfully transmitted to the cantilever.

[0019] The hard powder to be mixed with the bonding resin is made of gemstone materials such as diamond, ruby, sapphire, etc., or hard material powders such as boron, zirconia, hard glass, etc. These hard powders may be used alone or in combination. The mixing ratio of the hard powder is preferably as high as the ratio of the hard powder, since the ratio of the bonding resin decreases as the ratio increases, but if the ratio is too high, the adhesive function decreases, so the mixing ratio is determined taking into consideration the strength of the adhesive after it hardens.

[0020] The resin used for bonding may be a conventional epoxy resin adhesive, but it is more preferable to use an ultraviolet-curing resin that is cured by irradiating ultraviolet light. The ultraviolet-curing resin is suitable for the purpose of the present invention because it contains few components such as curing assistants and has high hardness after curing. However, if the ultraviolet light does not penetrate sufficiently into the resin during the curing process, it will take a long time to cure or sufficient curing will not be achieved. However, the hard powder used in the present invention is basically a material that easily transmits ultraviolet light, so it is compatible with the ultraviolet-curing resin. [Brief description of the drawings]

[0021] [Figure 1] 4 is a partial cross-sectional view showing a joint structure between a cantilever and a stylus of the cartridge of the present invention. FIG. [Diagram 2] FIG. 1 is a perspective view showing a structure of a typical cartridge. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described with reference to FIG.

[0023] In Fig. 1, the cantilever 1 is made of diamond or the like that has been crystallized into a rod shape. Therefore, it is not cylindrical like metal, but is a so-called solid member that is filled with a substance. Although not shown, the cantilever 1 is designed to move around a rubber damper or the like attached to the back of the cantilever, and a coil or magnet is attached midway to generate electromotive force, which is the same as a conventional cartridge structure.

[0024] The tip of the cantilever 1 is nearly parallel to the record surface and needs to have a flat surface 2 for mounting the stylus 4. However, because the material is solid diamond, it is not possible to crush the tip to form a flat section. For this reason, the tip of the cantilever 1 is polished with diamond powder of the same hardness to form the flat section 2.

[0025] A through hole 3 slightly larger in diameter than the stylus 4 is formed in the formed flat portion 2, the stylus 4 is attached here, and adhesive resin is injected between the through hole 3 and the stylus 4 and solidified to form an adhesive resin layer 5, thereby bonding the cantilever 1 and the stylus 4.

[0026] With this configuration, the displacement picked up by the stylus 4 from the groove of the record is transmitted to the cantilever 1 via the adhesive resin layer 5 .

[0027] As described above, the present invention can minimize displacement of the record groove picked up by the stylus 4 during record playback, such as that absorbed by the adhesive resin layer 5, making it possible to faithfully transmit the displacement to the cantilever 1.

[0028] Furthermore, when an ultraviolet curable resin is used as the adhesive resin, the resin has a high hardness and the hard powder mixed into the resin has excellent ultraviolet transmittance, so that the resin layer can be cured reliably all the way to the inside. [Explanation of symbols]

[0029] 1 Cantilever 2 Plane part 3 Through holes 4. Stylus 5 Adhesive resin layer 11. Magnets 12 York 13 Metallic materials 14. Gap 15 Rubber damper 16 Plate-shaped member 17 Coil

Claims

1. This is a joint structure between a stylus that follows the record groove and a cantilever that holds the stylus in a cartridge that extracts an acoustic signal from a record, characterized in that the resin used to join the stylus attached to the hole at the tip of the cantilever is a resin mixed with hard powder.

2. 2. A joint structure for a cantilever and a stylus according to claim 1, wherein the hard powder is any one of diamond, ruby, sapphire, boron, zirconia, hard glass, or a mixture thereof.

3. 3. The joint structure between a cantilever and a stylus according to claim 1, wherein an ultraviolet-curable resin is used as the resin used to join the cantilever and the stylus.

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