Pickup device and electric string instrument

Abstract

While maintaining a reduction in hum noise, the coil is made smaller and deterioration in sound quality is suppressed. [Solution] The pickup device 100 comprises a first coil 10 wound in a first direction around a magnetic core close to a string, a second coil 20 connected in series to the first coil 10 and wound in a second direction different from the first direction, a third coil 30 connected in series to the second coil 20 and wound in the second direction, and an adjustment circuit TC, wherein the adjustment circuit includes a first variable resistor Rv1 connected to the first coil 10 and the second coil 20 and adjusting the magnitude of the induced electromotive force of the second coil 20, the first coil 10 being configured to detect vibrations of the string and external magnetic field noise different from the string vibrations, and the second coil 20 and the third coil 30 being configured mainly to detect the external magnetic field noise.

Description

[Technical Field]

[0001] The present invention relates to a pickup device and an electric stringed instrument. [Background technology]

[0002] Electric guitars include pickups. Pickups include single-coil pickups, which convert string vibrations into an electrical signal, and humbucker pickups, which have two coils. When a single-coil pickup is used on an electric guitar, the output tone contains hum noise caused by changes in the external magnetic field. A humbucker pickup can eliminate external magnetic field noise from the output tone. A humbucker pickup includes a coil (hereafter referred to as coil A) that converts string vibrations into an electrical signal, and an additional coil (hereafter referred to as coil B) that is directly connected to coil A, has nearly identical characteristics to coil A, and is wound in the opposite direction. In a humbucker pickup, coils A and B detect string vibrations and external magnetic field noise, and their outputs are added together. This allows the output tone of the string vibrations to be reproduced while eliminating external magnetic field noise.

[0003] In a humbucker pickup, the higher the inductance value of coil B, the lower the peak frequency of the output sound. For this reason, the tone of a humbucker pickup is sometimes described as "rounder" or "mellower" compared to that of a single-coil pickup. However, there is also a desire to eliminate hum while maintaining the tone of a single-coil pickup. To achieve this, for example, to bring the sound quality of a humbucker pickup closer to that of a single-coil pickup, the inductance value of coil B must be reduced. However, in this case, the characteristics of coils A and B are no longer equivalent, making it difficult to eliminate external magnetic field noise. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 7,259,318 Summary of the Invention [Problem to be solved by the invention]

[0005] The pickup device of Patent Document 1 includes a coil A used in a single-coil pickup and another large coil (hereinafter referred to as coil C) connected to coil A via an adjustment circuit. Only coil A detects string vibration, while coils A and C detect changes in the external magnetic field. In the pickup of Patent Document 1, the number of turns of coil C, which is different from coil A (the coil that detects string vibration), is reduced to reduce its inductance (to suppress its impact on the tone). Generally, the fewer the number of turns, the smaller the induced electromotive force generated in the coil. However, in Patent Document 1, the cross-sectional area of ​​coil C is increased to ensure sufficient induced electromotive force to remove external magnetic field noise. Furthermore, the adjustment circuit adjusts the amplitude of the induced electromotive force in coil C (the amplitude of external magnetic field noise), thereby improving the removal performance of external magnetic field noise. This makes it possible to remove hum while maintaining the tone of a single-coil pickup (strictly speaking, the high-frequency characteristics are attenuated due to the influence of coil C).

[0006] On the other hand, if the cross-sectional area of ​​Coil C is large, for example, when mounting it on an electric string instrument such as an electric guitar, the cross-sectional area of ​​the groove formed in the body of the electric guitar to accommodate the coil must be made larger. From the standpoint of both sound quality and design, it is desirable to avoid forming a groove with a large cross-sectional area in the body of an electric guitar. Therefore, there is a demand for miniaturization of the coils used in pickups.

[0007] If you try to reduce the cross-sectional area of ​​Coil C, you need to increase the number of turns of Coil C to ensure the induced electromotive force. However, in this case, as mentioned above, the inductance value of Coil C increases, and the sound quality deteriorates compared to a single-coil pickup (the tone of a single-coil pickup changes, and the high-frequency characteristics in particular become attenuated). Thus, if you want to maintain a reduction in hum noise, there are contradictory requirements to making the coil smaller and minimizing the deterioration in sound quality.

[0008] In consideration of the above circumstances, one aspect of the present disclosure is a pickup device that can achieve a smaller coil and suppress deterioration in sound quality while maintaining a reduction in hum noise. [Means for solving the problem]

[0009] A pickup device according to one aspect of the present invention is a pickup device that detects vibrations of the strings of an electric stringed instrument, and includes: a magnetic core located near the strings; a first coil wound in a first direction relative to the magnetic core; a second coil connected in series to the first coil and wound in a second direction different from the first direction; a third coil connected in series to the second coil and wound in the second direction; and a variable resistor connected to the first coil and the second coil for adjusting the magnitude of the induced electromotive force in the second coil, wherein the first coil is configured to detect vibrations of the strings and external magnetic field noise other than string vibrations, and the second coil and third coil are configured to mainly detect external magnetic field noise.

[0010] An electric stringed instrument according to another aspect of the present invention includes the above pickup device. [Effects of the Invention]

[0011] It is possible to reduce the size of the coil that mainly detects external magnetic field noise and suppress deterioration in sound quality while maintaining a reduction in hum noise. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic plan view for explaining the configuration of a pickup device according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing an equivalent circuit of the pickup device according to the first embodiment. [Figure 3] FIG. 10 is a diagram showing an equivalent circuit of a pickup device according to a second embodiment. [Figure 4] 10 is an equivalent circuit diagram showing a pickup device according to another embodiment. [Figure 5] FIG. 10 is a perspective view showing a second coil and a third coil according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] A pickup device and an electric stringed instrument according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0014] (1) First embodiment FIG. 1 is a schematic plan view illustrating the configuration of a pickup device according to a first embodiment. To clarify the positional relationships, arrows are attached in FIG. 1 to indicate the mutually orthogonal X, Y, and Z directions. The X and Y directions are orthogonal to each other in a horizontal plane, and the Z direction corresponds to the vertical direction. The pickup device 100 includes a single-coil pickup SP1 having a first coil 10, a second coil 20, and a third coil 30, and an adjustment circuit TC. The pickup device 100 is incorporated into a stringed instrument. In this embodiment, the pickup device 100 is incorporated into an electric guitar and converts string vibrations into electrical signals.

[0015] The first coil 10 has a bobbin 11. A coil wire (not shown) is wound around the bobbin 11 in a first direction. Six holes 12 corresponding to the strings of an electric guitar are formed at equal intervals in the bobbin 11. Each hole 12 extends in the Z direction. A pole piece 13 is inserted into each hole 12. The pole piece 13 is a cylindrical member made of steel. Each pole piece 13 is magnetized by itself or is magnetically charged by contact with a magnet (not shown). The first coil 10 is composed of the bobbin 11, the pole piece 13, and the coil wire. The number of turns of the first coil 10 is appropriately selected from the range of 5,000 to 10,000. The number of turns of the first coil 10 is, for example, 7,000.

[0016] The second coil 20 and the third coil 30 are connected to the first coil 10 via an adjustment circuit TC. The adjustment circuit TC will be described later. Each of the second coil 20 and the third coil 30 is formed, for example, by winding a coil wire around an insulating structure (e.g., a bobbin). The number of turns of the third coil 30 is greater than that of the second coil 20. The number of turns of the first coil 10 is also greater than that of the third coil 30. Depending on the cross-sectional area of ​​the coil, the number of turns of the second coil 20 is appropriately selected from 200 to 700, taking into account implementation in a guitar. The number of turns of the second coil 20 is, for example, 450. The number of turns of the third coil 30 is appropriately selected from 1000 to 2000. The number of turns of the third coil 30 is, for example, 1500. The coil wire of each of the second coil 20 and the third coil 30 is wound in a second direction opposite to the direction (first direction) in which the coil wire is wound around the bobbin 11 of the first coil 10.

[0017] In this embodiment, string vibrations are detected by the first coil 10, and changes in the external magnetic field are detected by the first coil 10, the second coil 20, and the third coil 30. The first coil 10 can output a first signal containing string vibrations and external magnetic field noise, and the second coil 20 and the third coil 30 can output a second signal containing external magnetic field noise. Because the coil wires of the first coil 10, the second coil 20, and the third coil 30 are wound in opposite directions, the external magnetic field noise in the first signal and the external magnetic field noise in the second signal are 180 degrees out of phase. Therefore, by adding the first signal and the second signal while making the amplitude of the external magnetic field noise in the second signal the same as or similar to the amplitude of the external magnetic field noise in the first signal, the external magnetic field noise generated in the first coil 10 can be canceled out. This reduces hum.

[0018] In this embodiment, the second coil 20 and the third coil 30 each have an air core. The second coil 20 and the third coil 30 may each have a structure in which a core is inserted. The first coil 10 and the third coil 30 are connected to an amplifier 200. The amplifier 200 has a commonly used configuration, so a description thereof will be omitted.

[0019] 2 is a diagram showing an equivalent circuit of the pickup device 100 according to the first embodiment. The equivalent circuit of the first coil 10 is represented by a power source V1 for induced electromotive force v1, a resistor R1, a coil L1, and a capacitor C1. The equivalent circuit of the second coil 20 is represented by a power source V2 for induced electromotive force v2, a resistor R2, a coil L2, and a capacitor C2.

[0020] The adjustment circuit TC includes a variable resistor (volume) Rv1. The variable resistor Rv1 is, for example, a rotary volume. The variable resistor Rv1 of the adjustment circuit TC is connected in series with the second coil 20 and adjusts the amplitude of the induced electromotive force v2 in the second coil 20.

[0021] The variable resistor Rv1, coil L2, and capacitor C2 act as a low-pass filter for the induced electromotive force v2 in the second coil 20. Therefore, for example, if the inductance of the second coil 20 is large, its cutoff frequency will be low. In this case, the amplitude will decrease and the phase will shift, making it impossible to cancel out the external magnetic field noise. As a result, the timbre of the output sound will contain the external magnetic field noise. To eliminate the external magnetic field noise, it is necessary to reduce the inductance of the second coil 20, which is connected to the first coil 10 via the variable resistor Rv1.

[0022] Here, we will explain the inductance L of the coil. The first to third coils 10 to 30 are solenoid coils, and when the axial length of the coil is l, the cross-sectional area of ​​the coil is S, the number of turns of the coil is N, and the (apparent) magnetic permeability of the core is μ, the inductance L of the coil is expressed by the following formula (1).

number

[0023] Next, we will explain the induced electromotive force of a coil. If the magnetic field is a constant sine wave regardless of location, with an amplitude of α and a frequency of ω, the magnetic flux density B(t) is expressed by the following equation (2).

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[0024] Therefore, the pickup device 100 uses a third coil 30 that is different from the second coil 20. The equivalent circuit of the third coil 30 is represented by a power source V3 for induced electromotive force v3, a resistor R3, a coil L3, and a capacitor C3. The third coil 30 is connected in series with the second coil 20. This allows the induced electromotive force v3 of the third coil 30 to compensate for the shortage of induced electromotive force v2 of the second coil 20.

[0025] According to the pickup device 100 of the above embodiment, the cross-sectional area of ​​the second coil 20 can be reduced while also reducing the inductance value of the second coil 20. Furthermore, the cross-sectional area of ​​the third coil 30 need only be large enough to compensate for the shortage of the induced electromotive force v2 of the second coil 20. Therefore, the cross-sectional area of ​​the third coil 30 can be reduced. As a result, it is possible to reduce the size of the coils in the pickup device 100 and suppress deterioration in sound quality while maintaining a reduction in hum noise.

[0026] Furthermore, since the second coil 20 has an air core, the magnetic permeability is small within the second coil 20. Therefore, the inductance value of the second coil 20 can be further reduced.

[0027] (2) Second embodiment Here, the resonant frequency of the coil will be explained. If the inductance of the coil is L and the capacitance of the coil is C, the resonant frequency f0 is expressed by the following equation (4).

number

[0028] FIG. 3 is a diagram showing an equivalent circuit of pickup device 100A according to the second embodiment. The pickup device 100A according to the second embodiment differs from pickup device 100 according to the first embodiment in the following respects: A filter FT is connected to third coil 30, which may be involved in the generation of resonance and antiresonance. Filter FT is a low-pass filter including resistor RA and capacitor CA. In this case, filter FT functions as a filter for improving high-frequency characteristics, thereby stabilizing fluctuations in the amplitude of string vibration in the high wavelength band, thereby suppressing degradation in sound quality.

[0029] (3) Third embodiment In the above embodiment, an example is shown in which pickup device 100 includes one single-coil pickup SP1 (first coil 10), but pickup device 100 may include multiple single-coil pickups. FIG. 4 is an equivalent circuit diagram showing pickup device 100B according to another embodiment. Pickup device 100B differs from pickup device 100 in the following respects. Pickup device 100B includes single-coil pickups SP2 and SP3 that are different from single-coil pickup SP1, and a pickup selector PS. Single-coil pickups SP2 and SP3 are fourth coil 40 and fifth coil 50.

[0030] The adjustment circuit TC further includes variable resistors Rv2 and Rv3 corresponding to the fourth coil 40 and fifth coil 50. The variable resistors Rv2 and Rv3 are, for example, rotary potentiometers. The fourth coil 40 is connected to the variable resistor Rv2, and the fifth coil 50 is connected to the variable resistor Rv3. The equivalent circuits of the fourth coil 40 and the fifth coil 50 are similar to the equivalent circuit of the first coil 10 and are therefore not shown. The first coil 10, the fourth coil 40, and the fifth coil 50 are connected to a pickup selector PS. The pickup selector PS switches the single-coil pickups connected to the amplifier 200.

[0031] In pickup device 100B, the induced electromotive force in first coil 10 is designated v11, the induced electromotive force in fourth coil 40 is designated v12, and the induced electromotive force in fifth coil 50 is designated v13. In pickup device 100B, the induced electromotive force in second coil 20 is designated v2, and the induced electromotive force in third coil 30 is designated v3. In pickup device 100B, induced electromotive force v2 is smaller than the minimum value of induced electromotive forces v11 to v13, and the sum of induced electromotive forces v2 and v3 is larger than the maximum value of induced electromotive forces v11 to v13. When pickup device 100B according to the third embodiment is mounted on a guitar, single-coil pickups SP1 to SP3 can be switched, allowing the player to enjoy multiple tones. While pickup device 100B according to the third embodiment has three single-coil pickups, the number of single-coil pickups provided in pickup device 100B is not limited to this. The pickup device 100B may include two or more single coil pickups.

[0032] (4) Other embodiments In the pickup device 100 of the above embodiment, an example in which the second coil 20 and the third coil 30 are provided separately has been described, but the present invention is not limited to this. FIG. 5 is a perspective view showing the second coil 20 and the third coil 30 according to another embodiment. As shown in FIG. 5, the second coil 20 and the third coil 30 may be integrally fixed (stacked) so as to be aligned in the vertical direction (Z direction). In this case, the pickup device 100 becomes compact, making it easier to mount the pickup device 100 on a guitar.

[0033] (5) Correspondence between each component of the claims and each part of the embodiment Below, an example of the correspondence between each component of the claims and each element of the embodiments will be described. In the above embodiments, the pole piece 13 is an example of a magnetic core, the first coil 10 is an example of a first coil, the second coil 20 is an example of a second coil, the third coil 30 is an example of a third coil, and the fourth coil 40 is an example of a fourth coil. The adjustment circuit TC is an example of an adjustment circuit, the variable resistor Rv1 is an example of a first variable resistor, the variable resistor Rv2 is an example of a second variable resistor, and the filter FT is an example of a filter.

[0034] (6) Summary of implementation form (Item 1) The pickup device according to the present invention is A pickup device for detecting vibrations of strings of an electric stringed instrument, comprising: a magnetic core adjacent to the string; a first coil wound in a first direction around the magnetic core; a second coil connected in series to the first coil and wound in a second direction different from the first direction; a third coil wound in the second direction and connected in series with the second coil; an adjustment circuit; the adjustment circuit includes a first variable resistor connected to the first coil and the second coil and configured to adjust the magnitude of the induced electromotive force in the second coil; the first coil is configured to detect vibrations of the string and external magnetic field noise different from the vibrations of the string; The second coil and the third coil are configured to detect the external magnetic field noise.

[0035] According to the pickup device described in paragraph 1, the first coil, the second coil, and the third coil are wound in opposite directions, so that external magnetic field noise detected by the first coil can be canceled out, thereby reducing hum noise.

[0036] In the pickup device described in paragraph 1, the first variable resistor and the second coil function as a low-pass filter. When the inductance value of the second coil is large, the cutoff frequency is lowered. This results in a decrease in amplitude and a phase shift, which can result in external magnetic field noise being included in the timbre of the output sound. To eliminate external magnetic field noise, it is necessary to reduce the inductance value of the second coil connected to the first coil via the first variable resistor. In this case, it is possible to reduce the cross-sectional area of ​​the second coil. On the other hand, if the cross-sectional area of ​​the second coil is reduced, there may be insufficient induced electromotive force to cancel out the component of the induced electromotive force v1 generated in the first coil due to changes in the external magnetic field.

[0037] In the pickup device of paragraph 1, the second coil and the third coil are connected in series. Therefore, the third coil can compensate for the insufficient induced electromotive force, allowing the inductance value of the second coil constituting the low-pass filter to be reduced. Furthermore, the cross-sectional area of ​​the third coil need only be large enough to compensate for the insufficient induced electromotive force in the second coil. As a result, it is possible to achieve a smaller coil size and minimize degradation in sound quality while maintaining a reduction in hum noise.

[0038] (Item 2) The pickup device according to item 1, the first coil outputs a first signal including the external magnetic field noise; the second coil and the third coil output a second signal including the external magnetic field noise; The first signal and the second signal are added together while the amplitude of the second signal is made the same as or close to the amplitude of the first signal by the first variable resistor, thereby removing the external magnetic field noise detected by the first coil from the first signal.

[0039] According to the pickup device described in paragraph 2, the first coil, the second coil, and the third coil are wound in opposite directions, so the first signal and the second signal are 180 degrees out of phase with each other. By adding the first signal and the second signal while the amplitudes of the first signal and the second signal are the same or similar, it becomes possible to output an appropriate string vibration signal with external magnetic field noise removed from the first signal.

[0040] (Item 3) The pickup device according to item 1 or 2, a fourth coil wound in the first direction about a magnetic core adjacent to the string; The adjustment circuit further includes a second variable resistor connected to the fourth coil and the second coil, for adjusting the magnitude of the induced electromotive force in the second coil.

[0041] According to the pickup device described in paragraph 3, since it includes a plurality of coils that detect vibrations of the strings, when it is mounted on a stringed instrument, the player can enjoy a variety of tones.

[0042] (4) The pickup device according to any one of the first to third aspects, a filter connected to the third coil; The filter includes a capacitor and a resistor.

[0043] According to the pickup device described in paragraph 4, a first variable resistor is connected to the second coil, and a filter is connected to the third coil. The filter includes a capacitor and a resistor, and functions as a filter for improving high-frequency characteristics. This stabilizes the fluctuations in the amplitude of the string vibration output in the high-frequency band.

[0044] (Item 5) In the pickup device according to any one of items 1 to 4, The second coil is air-core.

[0045] According to the pickup device described in paragraph 5, the magnetic permeability inside the coil can be reduced, so that the inductance of the second coil can be easily reduced.

[0046] (Item 6) In the pickup device according to any one of items 1 to 5, The third coil is an air core.

[0047] According to the pickup device described in paragraph 6, the magnetic permeability inside the coil can be reduced, so that the inductance of the third coil can be easily reduced.

[0048] (Item 7) In the pickup device according to any one of items 1 to 6, The second coil and the third coil are integrally stacked in the vertical direction.

[0049] According to the pickup device described in paragraph 7, a compact configuration can be achieved.

[0050] (Item 8) An electric stringed instrument equipped with the pickup device according to any one of items 1 to 7.

[0051] According to the electric stringed instrument described in paragraph 8, it is possible to provide an electric stringed instrument including a pickup device that can realize a miniaturized coil and suppress the influence on sound quality of a single coil pickup. [Explanation of symbols]

[0052] 10...first coil, 11...bobbin, 12...hole, 13...pole piece, 20...second coil, 30...third coil, 40...fourth coil, 50...fifth coil, 100, 100A, 100B: pickup device, 200...amplifier, C1 to C3, CA...capacitor, FT...filter, L...inductance, L1 to L3...coil, PS...pickup selector, R1 to R3, RA...resistance, Rv1 to Rv3...variable resistor, S...cross-sectional area, SP1 to SP3...single coil pickup, TC...adjustment circuit, V1 to V3, V11 to V13...equivalent power supply (induced electromotive force)

Claims

1. A pickup device for detecting vibrations of strings of an electric stringed instrument, comprising: a first coil wound in a first direction about a magnetic core adjacent to the string; a second coil connected in series to the first coil and wound in a second direction different from the first direction; a third coil wound in the second direction and connected in series with the second coil; an adjustment circuit; the adjustment circuit includes a first variable resistor connected to the first coil and the second coil and configured to adjust the magnitude of the induced electromotive force in the second coil; the first coil is configured to detect vibration of the string and external magnetic field noise different from the vibration of the string; The pickup device, wherein the second coil and the third coil are configured to mainly detect the external magnetic field noise.

2. the first coil outputs a first signal including the external magnetic field noise; the second coil and the third coil output a second signal including the external magnetic field noise; 2. The pickup device according to claim 1, wherein the external magnetic field noise detected by the first coil is removed from the first signal by adding the first signal and the second signal while the amplitude of the second signal is made the same as or similar to the amplitude of the first signal by the first variable resistor.

3. a fourth coil wound in the first direction about a magnetic core adjacent to the string; 3. The pickup device according to claim 1, wherein the adjustment circuit further includes a second variable resistor connected to the fourth coil and the second coil, for adjusting the magnitude of the induced electromotive force in the second coil.

4. a filter connected to the third coil; 3. The pickup device according to claim 1, wherein the filter includes a capacitor and a resistor.

5. 3. The pickup device according to claim 1, wherein the second coil has an air core.

6. 3. The pickup device according to claim 1, wherein the third coil has an air core.

7. 3. The pickup device according to claim 1, wherein the second coil and the third coil are integrally stacked in the vertical direction.

8. 3. An electric stringed instrument comprising the pickup device according to claim 1.

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