Noise reduction device and musical instrument

Abstract

This noise reduction device (dummy coil 1) is attached to a musical instrument (electric guitar 7) having an electromagnetic pickup 72 for detecting a magnetic field change based on vibration of a string 71. The noise reduction device includes a coil 20, a core material 4 made of a soft magnetic material, and an adjustment member 3 for variably adjusting a relative position of the coil 20 and the core material 4. The core material 4 is not magnetized.

Description

Noise reduction devices and musical instruments

[0001] The present invention relates to noise reduction techniques used in musical instruments that have electromagnetic pickups.

[0002] Electric guitars use electromagnetic pickups to convert string vibrations into electrical signals. Electromagnetic pickups are divided into single-coil pickups and humbuckers (humbucking pickups). The output signal of a single-coil pickup contains hum, a type of environmental magnetic noise. Humbuckers have two coils wound in opposite directions and are connected to each other, which allows them to cancel hum. However, humbuckers have a different tone than single-coil pickups. Therefore, there is a demand for pickups that can cancel hum while maintaining the tone of a single pickup coil.

[0003] In the following Patent Document 1, a low-impedance dummy coil is connected to a single-coil pickup. This attempts to cancel hum while maintaining the tone of the single-coil pickup. In Patent Document 1, the size of the dummy coil is increased to ensure an induced electromotive force for canceling the hum. As a result, the dummy coil is large, which places significant restrictions on its installation on a guitar.

[0004] U.S. Patent No. 7,259,318

[0005] Patent Document 1 proposes a mechanism for canceling noise using a dummy coil. However, the hum noise generated in electric guitars varies between products due to manufacturing variations in the components that make them up.

[0006] An object of the present invention is to provide a noise reduction device that can achieve optimal noise cancellation depending on the product.

[0007] A noise reduction device according to one aspect of the present invention is a noise reduction device that is attached to a musical instrument having an electromagnetic pickup that detects magnetic field changes due to string vibrations, and is equipped with a coil, a core material made of a soft magnetic material, and an adjustment member that variably adjusts the relative position of the coil and the core material, and the core material is not magnetized.

[0008] Another aspect of the present invention provides a musical instrument comprising an electromagnetic pickup that detects magnetic field changes due to string vibrations, and a noise reduction device, the noise reduction device having a coil wound in the opposite direction to the electromagnetic pickup coil, a core material made of a soft magnetic material, and an adjustment member that variably adjusts the relative position of the coil and the core material, the core material being unmagnetized.

[0009] Another aspect of the present invention provides a musical instrument that includes an electromagnetic pickup that detects magnetic field changes due to string vibrations, and a noise reduction device. The noise reduction device has a coil wound in the opposite direction to the electromagnetic pickup coil, a core material made of a soft magnetic material, and an adjustment member that variably adjusts the relative position of the coil and the core material, and the noise reduction device does not detect magnetic field changes due to string vibrations at a perceptible level.

[0010] Another aspect of the present invention provides a musical instrument comprising an electromagnetic pickup that detects magnetic field changes due to string vibrations, and a noise reduction device, the noise reduction device having a coil wound in the opposite direction to the electromagnetic pickup coil, a core material made of a soft magnetic material, and an adjustment member that variably adjusts the relative position of the coil and the core material, the noise reduction device being attached to the musical instrument in a second region different from the first region where the electromagnetic pickup is attached, and the second region includes an area that is not affected by magnetic field changes due to string vibrations.

[0011] According to the present invention, it is possible to provide a noise reduction device that can achieve optimal noise cancellation depending on the product.

[0012] FIG. 1 is a perspective view of a dummy coil according to an embodiment. FIG. 2 is a block diagram showing the configuration of an electric guitar. FIG. 3 is a perspective view showing a bobbin of a dummy coil. FIG. 4 is a perspective view showing an adjustment member inserted into the bobbin. FIG. 5 is a perspective view showing a core material inserted into the adjustment member. FIG. 6 is a view showing a method for adjusting the insertion length of the adjustment member. FIG. 7 is a view showing another example of the appearance of a dummy coil. FIG. 8 is a view showing a method for adjusting the insertion length of the adjustment member. FIG. 9 is a view showing the front side of the body of an electric guitar showing the attachment position of a dummy coil. FIG. 10 is a view showing the back side of the body of an electric guitar showing the attachment position of a dummy coil. FIG. 11 is a perspective view of a dummy coil according to a modified example. FIG. 12 is a perspective view of a dummy coil according to a modified example. FIG. 13 is a view showing a dummy coil formed by connecting three coil sets. FIG. 14 is a view showing a dummy coil formed by connecting three coil sets.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A noise reduction device and a musical instrument according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0014] {1. Configuration of the Dummy Coil} The configuration of a dummy coil 1, which is one embodiment of a noise reduction device according to the present invention, will be described. FIG. 1 is a perspective view of the dummy coil 1 according to this embodiment. As shown in the figure, the dummy coil 1 is configured to include a bobbin 2, a coil 20 wound around the bobbin 2, an adjustment member 3, and a core material 4. Although a clear up-down direction is not particularly defined for the dummy coil 1, for convenience, the up-down direction in FIG. 1 will be described as the up-down direction of the dummy coil 1. In the following description, the symbol U in the drawings will be described as the up-down direction of the dummy coil 1, and the symbol D will be described as the down-down direction of the dummy coil 1. Therefore, in FIG. 1 and other figures, the up-down direction of the dummy coil 1 corresponds to the axial direction of the dummy coil 1.

[0015] In this embodiment, the dummy coil 1 will be described as being attached to an electric guitar 7. FIG. 2 is a block diagram showing the configuration of the electric guitar 7. The electric guitar 7 is equipped with an electromagnetic pickup 72 that detects magnetic field changes due to the vibration of strings 71. The electromagnetic pickup 72 is a single-coil pickup. The dummy coil 1 is connected to the electromagnetic pickup 72 and cancels the hum noise output from the electromagnetic pickup 72. The electromagnetic pickup 72 and the dummy coil 1 are connected in series. To cancel the hum noise, the dummy coil 1 and the electromagnetic pickup 72 are configured so that the coils are wound in opposite directions, resulting in opposite directions of induced electromotive force. By connecting the dummy coil 1 and the electromagnetic pickup 72 in series, which have coils wound in opposite directions, a signal can be obtained by subtracting the output signal of the dummy coil 1 from the output signal of the electromagnetic pickup 72. In this case, the output signals of the dummy coil 1 and the electromagnetic pickup 72 contain signals based on the same noise. Therefore, by subtracting the output signal of the dummy coil 1 from the output signal of the electromagnetic pickup 72, the noise contained in the output signal of the electromagnetic pickup 72 can be canceled.

[0016] 3 is a perspective view showing the bobbin 2 of the dummy coil 1. The bobbin 2 has a cylindrical portion 21 that is substantially cylindrical and extends in the vertical direction. The bobbin 2 has a disk portion 22U located at the upper end of the cylindrical portion 21 and a disk portion 22D located at the lower end. In this embodiment, the cylindrical portion 21 and the disk portions 22U and 22D are integrally molded from resin. As shown in FIG. 1, the coil 20 is wound around the outer periphery of the cylindrical portion 21. As described above, the coil 20 wound around the cylindrical portion 21 is connected to the coil of the electromagnetic pickup 72.

[0017] A cylindrical space 23 is formed in the center of the cylindrical portion 21. The adjustment member 3 is inserted into the space 23. A screw groove 21a is formed in the inner diameter portion of the cylindrical portion 21.

[0018] FIG. 4 is a perspective view showing the adjustment member 3. The adjustment member 3 is a member for variably adjusting the relative position between the coil 20 and the core material 4. The adjustment member 3 is a cylindrical member. In this embodiment, the adjustment member 3 is made of resin. The adjustment member 3 is inserted into the space 23 of the bobbin 2. Three holes 31S are formed in the upper surface 31 of the adjustment member 3. Each of the holes 31S is a cylindrical hole. In this embodiment, the three holes 31S have the same diameter and depth. The core material 4 is inserted into these three holes 31S.

[0019] A screw groove 32a is formed on the outer periphery of the cylindrical portion 32 of the adjustment member 3. The adjustment member 3 is inserted from above the bobbin 2 while aligning it with the space 23 of the bobbin 2, and the screw groove 21a and the screw groove 32a are screwed together, thereby making it possible to adjust the insertion length (insertion depth) of the adjustment member 3 into the space 23. Fig. 1 shows the state in which the adjustment member 3 is completely inserted into the space 23.

[0020] FIG. 5 is a perspective view showing the core material 4. The core material 4 is inserted into the hole 31S of the adjustment member 3. The core material 4 is inserted in the axial direction of the dummy coil 1. As described above, the three holes 31S formed in the adjustment member 3 have the same shape. Therefore, in this embodiment, the three core materials 4 have the same shape. In this embodiment, the core material 4 is made of a soft magnetic material. Also, in this embodiment, the core material 4 is not magnetized. Because the core material 4 is not magnetized, the dummy coil 1 does not pick up string vibrations and can pick up only noise. For example, ferrite can be used as the core material 4. The dummy coil 1 of this embodiment ensures the necessary induced electromotive force by inserting the core material 4 (core) even when the coil is small and has a small number of coil turns.

[0021] In this embodiment, the number of holes 31S formed in the adjustment member 3 is three, but this number is not particularly limited. The number of holes 31S may be one or two, or may be four or more. The number of holes 31S may be determined according to the number of core materials 4 to be inserted. Also, in this embodiment, the three holes 31S have the same cylindrical shape, but the shape is not limited to a cylindrical shape, and the shapes of the holes 31S may be different. The shape of the core materials 4 to be inserted may be determined accordingly.

[0022] {2. Adjustment of the Adjusting Member} Figure 6 is a diagram showing a method for adjusting the insertion position of the adjusting member 3 relative to the bobbin 2. As shown in the top diagram of Figure 6, the adjusting member 3 is inserted into the space 23 of the bobbin 2 from above. The top diagram shows a state in which approximately one-third of the vertical length of the adjusting member 3 is inserted into the space 23. The second diagram from the top shows a state in which approximately two-thirds of the vertical length of the adjusting member 3 is inserted into the space 23. The bottom diagram shows a state in which the entire adjusting member 3 is inserted into the space 23. This insertion length of the adjusting member 3 can be adjusted by screwing the adjusting member 3 into the bobbin 2.

[0023] In this way, by adjusting the insertion length (insertion depth) of the adjustment member 3 into the bobbin 2, the relative position of the adjustment member 3 with respect to the dummy coil 1 in the axial direction of the dummy coil 1 is adjusted. This adjusts the core insertion length of the dummy coil 1. In other words, by adjusting the insertion length of the adjustment member 3 into the bobbin 2, the insertion length of the core material 4 in the axial direction of the dummy coil 1 is adjusted. By adjusting the axial insertion length of the core material 4 in the dummy coil 1, the apparent permeability of the dummy coil 1 changes. In this way, since the induced electromotive force is proportional to the permeability, by adjusting the insertion length of the adjustment member 3 to change the apparent permeability of the dummy coil 1, the dummy coil 1 of this embodiment can adjust the magnitude of the induced electromotive force.

[0024] The dummy coil 1 of this embodiment can adjust the insertion length of the adjustment member 3 to suit the electric guitar 7 to which it is attached, thereby adjusting the induced electromotive force of the dummy coil 1. This makes it possible to adjust the induced electromotive force of the dummy coil 1 according to the electromagnetic pickup 72 attached to the electric guitar 7, thereby canceling hum noise of the electromagnetic pickup 72. Although the induced electromotive forces of the electromagnetic pickup 72 and dummy coil 1 attached to electric guitars vary between products, this embodiment makes it possible to effectively cancel hum noise of the electromagnetic pickup 72 by adjusting the induced electromotive force of the dummy coil 1. This makes it possible to cancel hum noise while maintaining the tone of the electromagnetic pickup 72, which is a single-coil pickup.

[0025] {3. Appearance of the Dummy Coil} The dummy coil 1 shown in FIG. 1 has a substantially cylindrical appearance. However, the appearance shape of the dummy coil 1 is not limited to this. For example, as shown in FIG. 7, it may have a horizontally elongated shape. The dummy coil 1A shown in FIG. 7 has a shape similar to a single pickup. In the drawings, the symbol U represents the upward direction of the dummy coil 1A, and the symbol D represents the downward direction of the dummy coil 1A. Furthermore, in the drawings, the symbol L represents the leftward direction of the dummy coil 1A, and the symbol R represents the rightward direction of the dummy coil 1A. In FIG. 7, the vertical direction of the dummy coil 1A corresponds to the axial direction of the dummy coil 1A. The structure of the dummy coil 1A is similar to the structure of the dummy coil 1 shown in FIGS. 3 to 5. The dummy coil 1A includes a bobbin 2 and a coil 20 wound around the bobbin 2. An adjustment member 3 capable of variably adjusting the insertion length is inserted into the bobbin 2. A core material 4 is inserted into the adjustment member 3.

[0026] The appearance of the bobbin 2 and the adjustment member 3 is similar to that of the dummy coil 1A, and is elongated like a single pickup. Unlike the dummy coil 1 shown in FIG. 1 etc., the dummy coil 1A has six core materials 4 inserted into the adjustment member 3. The core materials 4 are also arranged in a substantially linear fashion in the adjustment member 3. However, the number of core materials 4 held by the adjustment member 3 is not particularly limited.

[0027] A dial 5 is provided on the upper part of the adjustment member 3 for adjusting the insertion length of the adjustment member 3 relative to the bobbin 2. By operating the dial 5, the insertion length of the adjustment member 3 relative to the bobbin 2 is adjusted. For example, a shaft with a thread groove is connected to the dial 5, and the adjustment member 3 has a thread groove that screws into the thread groove of the dial 5. By rotating the dial 5, the adjustment member 3, which holds the core material 4, moves up and down.

[0028] FIG. 8 is a diagram showing a method for adjusting the insertion length of the adjustment member 3 relative to the bobbin 2. By operating the dial 5, the insertion position of the adjustment member 3 moves up and down relative to the bobbin 2. By adjusting the insertion length (insertion depth) of the adjustment member 3 relative to the bobbin 2, the relative position of the adjustment member 3 with respect to the dummy coil 1A in the axial direction of the dummy coil 1A is adjusted. This adjusts the core insertion length of the dummy coil 1A. In other words, by adjusting the insertion length of the adjustment member 3 relative to the bobbin 2, the insertion length of the core material 4 in the axial direction of the dummy coil 1A is adjusted. This changes the magnetic permeability of the dummy coil 1A. In this way, by adjusting the insertion length of the adjustment member 3, the dummy coil 1A of this embodiment can change its apparent magnetic permeability and adjust the magnitude of the induced electromotive force.

[0029] {4. Mounting Positions of Dummy Coils} The following describes the mounting positions of the above-described dummy coils 1, 1A on the electric guitar 7. Figures 9 and 10 are diagrams showing examples of mounting positions of the dummy coils 1, 1A. Areas 75a to 75f shown in Figures 9 and 10 indicate the mounting positions of the dummy coils 1, 1A.

[0030] As shown in FIG. 9 , three regions 75a, 75b, and 75c are shown on the front side 70F of the body 70 of the electric guitar 7 as examples of attachment positions for the dummy coils 1 and 1A. Also, as shown in FIG. 10 , three regions 75d, 75e, and 75f are shown on the back side 70B of the body 70 of the electric guitar 7 as examples of attachment positions for the dummy coils 1 and 1A. All of the regions 75a to 75f are regions that do not detect magnetic field changes caused by the vibration of the string 71 at a perceptible level. In other words, the regions 75a to 75f are not affected by magnetic field changes caused by the vibration of the string 71. Therefore, the regions 75a to 75f exclude the area directly below and around the string 71. The regions 75a to 75f shown in FIGS. 9 and 10 indicate attachment positions for the dummy coils 1 and 1A that are connected to the electromagnetic pickup 72 (single-coil pickup), which is the front pickup. Similarly, when connecting dummy coils 1 and 1A to the center pickup and rear pickup, the dummy coils 1 and 1A can be attached to areas 75a to 75f, etc. The dummy coil 1 is preferably attached as close to the pickup as possible, as long as the magnetic field change caused by string vibration is not detected at a perceptible level.

[0031] The area where the electromagnetic pickup 72 is attached is an example of the first area according to the present invention, and areas 75a, 75b, 75c, 75d, 75e, and 75f are examples of the second area according to the present invention. The first and second areas are areas that are subject to common environmental magnetic field noise (e.g., hum noise). In other words, by connecting the electromagnetic pickup 72 and the dummy coils 1 and 1A in series and winding them in opposite directions, it is possible to cancel the environmental noise. While FIGS. 9 and 10 illustrate an example in which the dummy coils 1 and 1A are attached to the front or back surface of the body 70, the dummy coils 1 and 1A may also be attached to the side surface of the body 70.

[0032] {5. Modification 1} Next, Modification 1 of the present invention will be described. FIGS. 11 and 12 are diagrams showing the appearance of a dummy coil 1B according to Modification 1. While the up, down, and left, and right directions of the dummy coil 1B are not clearly defined, in FIGS. 11 and 12, the symbol U in the drawings will be referred to as the upward direction of the dummy coil 1B, and the symbol D will be referred to as the downward direction of the dummy coil 1B. Furthermore, the symbol L in the drawings will be referred to as the leftward direction of the dummy coil 1B, and the symbol R will be referred to as the rightward direction of the dummy coil 1B. Therefore, in FIG. 11 and other figures, the upward and downward direction of the dummy coil 1B corresponds to the axial direction of the dummy coil 1B. As shown in FIG. 11, the dummy coil 1B, like the dummy coils 1 and 1A, includes a bobbin 2, a coil 20 wound around the bobbin 2, and a core material 4 inserted into a space 23 in the bobbin 2. In the example shown in the figures, four core materials 4 are inserted into the space 23, but the number of core materials 4 is not particularly limited. The number of core materials 4 may be three or less, or five or more.

[0033] In the above-described dummy coils 1 and 1A, the insertion length of the core material 4 was adjusted in the axial direction of the dummy coils 1 and 1A by adjusting the adjustment member 3. In the dummy coil 1B according to Modification 1, the position of the core material 4 is adjusted in the left-right direction of the dummy coil 1B by operating an adjustment member (not shown). In other words, the relative position of the core material 4 with respect to the dummy coil 1B is adjusted in the direction perpendicular to the coil axial direction. For example, the adjustment member is configured to be able to slide left and right within the space 23 of the bobbin 2 while holding the core material 4.

[0034] Thus, in the dummy coil 1B according to Modification 1, the position of the core material 4 is adjusted in a direction perpendicular to the coil axis. Generally, the closer to the coil, the greater the inductance inside the coil. In other words, the greater the apparent magnetic permeability. Therefore, the closer the core material 4 is to the coil, the greater the induced electromotive force in the dummy coil 1B. The dummy coil 1B in the state shown in FIG. 12 has a greater induced electromotive force than the dummy coil 1B shown in FIG. 11. This allows the dummy coil 1B according to Modification 1 to adjust the induced electromotive force of the dummy coil 1 in accordance with the electromagnetic pickup 72 attached to the electric guitar 7, effectively canceling the hum noise of the electromagnetic pickup 72. The dummy coil 1B can also be attached to the body of the electric guitar 7 in areas 75a to 75f, etc., shown in FIGS. 9 and 10.

[0035] {6. Modification 2} Next, Modification 2 of the present invention will be described. FIG. 13 is a diagram showing a dummy coil 1C according to Modification 2. The dummy coil 1C has a configuration in which three dummy coils 1Ca, 1Cb, and 1Cc are connected in series. The dummy coils 1Ca, 1Cb, and 1Cc are examples of a coil set according to the present invention. The dummy coils 1Ca, 1Cb, and 1Cc each have a configuration similar to the dummy coil 1 shown in FIG. 1. That is, the core insertion length of each of the dummy coils 1Ca, 1Cb, and 1Cc can be adjusted by adjusting the adjustment member 3. However, the dummy coils 1Ca, 1Cb, and 1Cc have different diameters of the bottom of the bobbin 2. In the example shown in FIG. 13, the diameter of the bottom of the dummy coil 1Ca is larger than that of the dummy coils 1Cb and 1Cc. The diameters of the bottom of the dummy coils 1Cb and 1Cc are approximately the same.

[0036] The dummy coils 1Ca, 1Cb, and 1Cc have different bottom diameters, and therefore different bottom areas of the coil 20. As a result, the magnitude of the induced electromotive force in the dummy coils 1Ca, 1Cb, and 1Cc also differs. If the electric guitar 7 has three electromagnetic pickups (first to third pickups), the hum noise of each of the three electromagnetic pickups is reduced by combining three coil sets as follows. However, the magnitude of the induced electromotive force in each electromagnetic pickup is set to be first < second < third.

[0037] The dummy coil 1Ca is connected to the first pickup. By adjusting the adjustment member 3 of the dummy coil 1Ca, the induced electromotive force of the dummy coil 1Ca is adjusted to match the first pickup. This allows the dummy coil 1Ca to reduce hum noise of the first pickup.

[0038] The composite dummy coil, which is formed by connecting dummy coils 1Ca and 1Cb in series, is connected to the second pickup. By adjusting the adjustment member 3 of the dummy coil 1Cb, the composite induced electromotive force of the dummy coils 1Ca and 1Cb is adjusted to match the second pickup. This allows the dummy coils 1Ca and 1Cb to reduce hum noise in the second pickup.

[0039] A composite dummy coil, consisting of dummy coils 1Ca, 1Cb, and 1Cc connected in series, is connected to the third pickup. By adjusting the adjustment member 3 of the dummy coil 1Cc, the composite induced electromotive force of the dummy coils 1Ca, 1Cb, and 1Cc is adjusted to match the third pickup. This allows the dummy coils 1Ca, 1Cb, and 1Cc to reduce hum noise in the third pickup.

[0040] In this way, by using the dummy coil 1C according to Modification 2, the dummy coil 1C can be made smaller. One method for reducing hum noise from multiple electromagnetic pickups is to attach individual dummy coils 1, 1A, 1B, etc., in one-to-one correspondence with each electromagnetic pickup. However, with the dummy coil 1C according to Modification 2, the second and third pickups can ensure induced electromotive force by combining multiple dummy coils, making it possible to reduce the size of the dummy coils 1Cb and 1Cc. The dummy coil 1C can also be attached to the body of the electric guitar 7 in areas 75a to 75f shown in Figures 9 and 10. While Modification 2 configures the dummy coils 1Ca, 1Cb, and 1Cc to have different bottom diameters, another modification would be to configure the dummy coils 1Ca, 1Cb, and 1Cc to have different axial lengths.

[0041] {7. Modification 3} Next, Modification 3 of the present invention will be described. Fig. 14 is a diagram showing a dummy coil 1D according to Modification 3. The dummy coil 1D has a configuration in which three dummy coils 1Da, 1Db, and 1Dc are connected in series. The dummy coils 1Da, 1Db, and 1Dc are an example of a coil set according to the present invention. Unlike the dummy coil 1C according to Modification 2, the dummy coil 1D according to Modification 3 has a configuration in which three dummy coils 1Da, 1Db, and 1Dc are stacked one above the other.

[0042] As shown in the figure, the three dummy coils 1Da, 1Db, and 1Dc share five core materials 4a to 4e. The dummy coil 1D is equipped with adjustment members that can individually adjust the positions of the core materials 4a to 4e in the vertical direction (coil axial direction), making it possible to adjust the core insertion length of each of the dummy coils 1Da, 1Db, and 1Dc. However, the dummy coils 1Da, 1Db, and 1Dc have different lengths in the vertical direction (axial direction) of the bobbin 2. In the example shown in FIG. 14, the axial length of the dummy coil 1Da is longer than that of the dummy coils 1Db and 1Dc. The axial lengths of the dummy coils 1Db and 1Dc are approximately the same.

[0043] The dummy coils 1Da, 1Db, and 1Dc have different axial lengths, and therefore different numbers of turns of the coil 20. As a result, the magnitude of the induced electromotive force in the dummy coils 1Da, 1Db, and 1Dc also differs. If the electric guitar 7 is equipped with three electromagnetic pickups (first to third pickups), the hum noise of each of the three electromagnetic pickups is reduced by combining three coil sets as follows. However, the magnitude of the induced electromotive force in each electromagnetic pickup is set to be first < second < third.

[0044] The dummy coil 1Da is connected to the first pickup. The composite dummy coil, which is formed by connecting dummy coils 1Da and 1Db in series, is connected to the second pickup. The composite dummy coil, which is formed by connecting dummy coils 1Da, 1Db, and 1Dc in series, is connected to the third pickup. By individually adjusting the core insertion lengths of the core materials 4a to 4e, the induced electromotive force of the dummy coil 1Da is adjusted to match the first pickup, the combined induced electromotive force of the dummy coils 1Da and 1Db is adjusted to match the second pickup, and the combined induced electromotive force of the dummy coils 1Da, 1Db, and 1Dc is adjusted to match the third pickup. As a result, the dummy coil 1Da reduces the hum noise of the first pickup, the dummy coils 1Da and 1Db reduce the hum noise of the second pickup, and the dummy coils 1Da, 1Db, and 1Dc reduce the hum noise of the third pickup.

[0045] In this way, by using the dummy coil 1D according to Modification 3, it is possible to reduce the size of the dummy coil 1D. As a method for reducing hum noise from multiple electromagnetic pickups, the dummy coil 1D according to Modification 3 ensures induced electromotive force in the second and third pickups by combining multiple dummy coils, making it possible to reduce the size of the dummy coils 1Db and 1Dc. The dummy coil 1D can also be attached to the body of the electric guitar 7 in areas 75a to 75f shown in Figures 9 and 10.

[0046] {8. Other Embodiments} In the above embodiment, an electric guitar 7 was used as an example of a musical instrument that uses the dummy coils 1, 1A, 1B, 1C, and 1D, but the dummy coil of the present invention can be used in other musical instruments that have an electromagnetic pickup. For example, it can also be used in an electric bass. The dummy coil 1 of the present invention has adjustable magnetic permeability and can detect environmental magnetic field noise but not detect magnetic field changes caused by string vibrations. Within the scope of its purpose, the dummy coil 1 of the present invention is not limited to the above embodiment and can be modified as appropriate.

[0047] {9. Features and Effects of the Embodiments} (1) A noise reduction device according to one aspect of the present invention is a noise reduction device that is attached to a musical instrument having an electromagnetic pickup that detects magnetic field changes due to string vibrations, and includes a coil, a core made of a soft magnetic material, and an adjustment member that variably adjusts the relative position between the coil and the core, and the core is not magnetized.

[0048] By incorporating a core material, the apparent magnetic permeability can be increased, enabling the noise reduction device to be compact while still maintaining the necessary induced electromotive force. Furthermore, the relative position of the coil and core material can be variably adjusted, allowing the induced electromotive force to be controlled appropriately for the instrument to which it is attached. This effectively reduces noise from the electrical signal output by the electromagnetic pickup.

[0049] (2) In the noise reduction device described in (1), the noise reduction device does not need to detect changes in the magnetic field caused by the vibration of the strings at a perceptible level.

[0050] Noise can be effectively reduced from the electrical signal output from the electromagnetic pickup.

[0051] (3) In the noise reduction device described in (1), the noise reduction device may be attached to the musical instrument in a region that is not affected by changes in magnetic field due to vibration of the strings.

[0052] Noise can be effectively reduced from the electrical signal output from the electromagnetic pickup.

[0053] (4) In the noise reduction device described in (1), the core material may be inserted in the axial direction inside the coil, and the adjustment member may adjust the insertion length of the core material in the axial direction of the coil.

[0054] By adjusting the position of the core material within the coil, it is possible to adjust the induced electromotive force to reduce noise depending on the instrument.

[0055] (5) In the noise reduction device described in (4), the adjustment member may be capable of holding the core material, and the insertion length of the core material in the axial direction of the coil may be adjusted by adjusting the relative position of the adjustment member in the axial direction of the coil.

[0056] By adjusting the position of the core material within the coil, it is possible to adjust the induced electromotive force to reduce noise depending on the instrument.

[0057] (6) In the noise reduction device according to (5), the adjustment member may hold a plurality of core materials.

[0058] The apparent permeability can be adjusted.

[0059] (7) In the noise reduction device described in (1), the core material may be inserted into the coil in the axial direction of the coil, and the adjustment member may adjust the relative position of the core material in a direction perpendicular to the axial direction of the coil.

[0060] By adjusting the position of the core material within the coil, it is possible to adjust the induced electromotive force to reduce noise depending on the instrument.

[0061] (8) In the noise reduction device according to (1), the core material may include ferrite.

[0062] The magnetic permeability of the core material can be increased.

[0063] (9) In the noise reduction device described in (1), the noise reduction device may have a plurality of coil sets each composed of a coil, a core material, and an adjustment member, and may generate a plurality of induced electromotive forces by combining the plurality of coil sets.

[0064] The size of the noise reduction device for generating multiple induced electromotive forces can be reduced.

[0065] (10) In the noise reduction device described in (9), the musical instrument may have a plurality of electromagnetic pickups, and the noise of each of the plurality of electromagnetic pickups may be reduced by combining a plurality of coil sets.

[0066] The size of the noise reduction device for multiple pickups can be reduced.

[0067] (11) Another aspect of the present invention provides a musical instrument that includes an electromagnetic pickup that detects magnetic field changes due to string vibrations, and a noise reduction device. The noise reduction device includes a coil wound in the opposite direction to the coil of the electromagnetic pickup, a core material made of a soft magnetic material, and an adjustment member that variably adjusts the relative position of the coil and the core material, and the core material is not magnetized.

[0068] By incorporating a core material, the apparent magnetic permeability can be increased, ensuring the necessary induced electromotive force while miniaturizing the noise reduction device. Furthermore, the relative position of the coil and core material can be variably adjusted, allowing for the appropriate induced electromotive force to be controlled for each instrument. This effectively reduces noise from the electrical signal output by the electromagnetic pickup.

[0069] (12) Another aspect of the present invention provides a musical instrument that includes an electromagnetic pickup that detects magnetic field changes due to string vibrations, and a noise reduction device. The noise reduction device has a coil wound in the opposite direction to the electromagnetic pickup coil, a core material made of a soft magnetic material, and an adjustment member that variably adjusts the relative position of the coil and the core material. The noise reduction device does not detect magnetic field changes due to string vibrations at a perceptible level.

[0070] Noise can be effectively reduced from the electrical signal output from the electromagnetic pickup.

[0071] (13) Another aspect of the present invention provides a musical instrument comprising an electromagnetic pickup that detects magnetic field changes due to string vibrations, and a noise reduction device, the noise reduction device having a coil wound in the opposite direction to the coil of the electromagnetic pickup, a core material made of a soft magnetic material, and an adjustment member that variably adjusts the relative position of the coil and the core material, the noise reduction device being attached to the musical instrument in a second region different from the first region where the electromagnetic pickup is attached, and the second region includes an area that is not affected by magnetic field changes due to string vibrations.

[0072] Noise can be effectively reduced from the electrical signal output from the electromagnetic pickup.

[0073] (14) In the musical instrument described in (13), the first area and the second area may be areas that are subject to a common environmental magnetic field noise.

[0074] Noise can be effectively reduced from the electrical signal output from the electromagnetic pickup.

[0075] (15) In the musical instrument described in any one of (11) to (13), the core material may be inserted into the coil in the axial direction of the coil, and the adjustment member may adjust the insertion length of the core material in the axial direction of the coil.

[0076] By adjusting the position of the core material within the coil, it is possible to adjust the induced electromotive force to reduce noise depending on the instrument.

[0077] (16) In the musical instrument described in (15), the adjustment member may be capable of holding the core material, and the insertion length of the core material in the axial direction of the coil may be adjusted by adjusting the relative position of the adjustment member in the axial direction of the coil.

[0078] By adjusting the position of the core material within the coil, it is possible to adjust the induced electromotive force to reduce noise depending on the instrument.

[0079] (17) In the musical instrument described in (16), the adjustment member may hold a plurality of core materials.

[0080] The apparent permeability can be adjusted.

[0081] (18) In the musical instrument described in any one of (11) to (13), the core material may be inserted axially inside the coil, and the adjustment member may adjust the relative position of the core material in a direction perpendicular to the axial direction of the coil.

[0082] By adjusting the position of the core material within the coil, it is possible to adjust the induced electromotive force to reduce noise depending on the instrument.

[0083] (19) In the musical instrument according to any one of (11) to (13), the core material may contain ferrite.

[0084] The magnetic permeability of the core material can be increased.

[0085] (20) In the musical instrument described in any one of (11) to (13), the noise reduction device may have a plurality of coil sets each consisting of a coil, a core material, and an adjustment member, and the musical instrument may have a plurality of coil sets, and a plurality of induced electromotive forces may be generated by combining the plurality of coil sets.

[0086] The size of the noise reduction device for generating multiple induced electromotive forces can be reduced.

[0087] (21) In the musical instrument described in (20), the musical instrument may have a plurality of electromagnetic pickups, and noise from each of the plurality of electromagnetic pickups may be reduced by combining a plurality of coil sets.

[0088] The size of the noise reduction device for multiple pickups can be reduced.

[0089] 1, 1A, 1B, 1C, 1D... dummy coil, 2... bobbin, 20... coil, 21... (bobbin) cylindrical portion, 21a... screw groove, 22... (bobbin) disc portion, 23... space, 3... adjustment member, 31... (adjustment member) upper surface, 31S... hole (for inserting core material), 32... cylindrical portion, 32a... screw groove, 4, 4a to 4e... core material, 5... dial, 7... electric guitar, 70... body, 70F... front side of body, 70B... rear side of body, 71... string, 72... electromagnetic pickup, 75a to 75f... dummy coil mounting area, U... up direction, D... down direction, L... left direction, R... right direction

Claims

1. A noise reduction device to be attached to a musical instrument having an electromagnetic pickup that detects magnetic field changes due to string vibrations, comprising: a coil; a core material made of a soft magnetic material; and an adjustment member that variably adjusts the relative position between the coil and the core material, wherein the core material is not magnetized.

2. The noise reduction device of claim 1, wherein said noise reduction device does not detect appreciable changes in the magnetic field due to vibration of said string.

3. The noise reduction device according to claim 1, wherein said noise reduction device is attached to said musical instrument in an area that is not affected by magnetic field changes due to vibration of said strings.

4. A noise reduction device as claimed in claim 1, wherein the core material is inserted axially inside the coil, and the adjustment member adjusts the insertion length of the core material in the axial direction of the coil.

5. A noise reduction device as described in claim 4, wherein the adjustment member is capable of holding the core material, and the insertion length of the core material in the axial direction of the coil is adjusted by adjusting the relative position of the adjustment member in the axial direction of the coil.

6. The noise reduction device according to claim 5, wherein said adjustment member holds a plurality of cores.

7. A noise reduction device as described in claim 1, wherein the core material is inserted inside the coil in the axial direction of the coil, and the adjustment member adjusts the relative position of the core material in a direction perpendicular to the axial direction of the coil.

8. The noise reduction device of claim 1, wherein the core material comprises ferrite.

9. The noise reduction device according to claim 1, comprising a plurality of coil sets each consisting of the coil, the core material, and the adjustment member, and wherein a plurality of induced electromotive forces are generated by combining the plurality of coil sets.

10. The noise reduction device of claim 9, wherein the musical instrument has a plurality of electromagnetic pickups, and the combination of the plurality of coil sets reduces noise from each of the plurality of electromagnetic pickups.

11. A musical instrument equipped with an electromagnetic pickup that detects magnetic field changes due to string vibrations, and a noise reduction device, wherein the noise reduction device has a coil wound in the opposite direction to the coil of the electromagnetic pickup, a core material made of a soft magnetic material, and an adjustment member that variably adjusts the relative position of the coil and the core material, wherein the core material is not magnetized.

12. A musical instrument equipped with an electromagnetic pickup that detects magnetic field changes due to string vibrations, and a noise reduction device, wherein the noise reduction device has a coil wound in the opposite direction to the coil of the electromagnetic pickup, a core material made of a soft magnetic material, and an adjustment member that variably adjusts the relative position of the coil and the core material, and wherein the noise reduction device does not detect magnetic field changes due to string vibrations at a perceptible level.

13. A musical instrument comprising an electromagnetic pickup that detects magnetic field changes due to string vibration, and a noise reduction device, wherein the noise reduction device has a coil wound in the opposite direction to the coil of the electromagnetic pickup, a core material made of a soft magnetic material, and an adjustment member that variably adjusts the relative position of the coil and the core material, wherein the noise reduction device is attached to the musical instrument in a second region different from a first region in which the electromagnetic pickup is attached, and the second region includes an area that is not affected by magnetic field changes due to string vibration.

14. The musical instrument of claim 13, wherein the first area and the second area are areas subject to a common environmental magnetic field noise.

15. A musical instrument as claimed in any one of claims 11 to 13, wherein the core material is inserted inside the coil in the axial direction of the coil, and the adjustment member adjusts the insertion length of the core material in the axial direction of the coil.

16. The musical instrument according to claim 15, wherein the adjustment member is capable of holding the core material, and the insertion length of the core material in the axial direction of the coil is adjusted by adjusting the relative position of the adjustment member in the axial direction of the coil.

17. The musical instrument of claim 16, wherein the tuning member holds a plurality of cores.

18. A musical instrument as claimed in any one of claims 11 to 13, wherein the core material is inserted axially inside the coil, and the adjustment member adjusts the relative position of the core material in a direction perpendicular to the axial direction of the coil.

19. The musical instrument according to any one of claims 11 to 13, wherein the core material comprises ferrite.

20. A musical instrument as described in any one of claims 11 to 13, wherein the noise reduction device has a plurality of coil sets each consisting of the coil, the core material, and the adjustment member, and the musical instrument has the plurality of coil sets, and a plurality of induced electromotive forces are generated by combining the plurality of coil sets.

21. The musical instrument of claim 20, wherein the musical instrument has a plurality of electromagnetic pickups, and the combination of the plurality of coil sets reduces noise for each of the plurality of electromagnetic pickups.

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