JP2002258864A - Sensor for detecting string vibration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a string vibration detection sensor which detects string vibration and in which overtone component ratios with respect to fundamental tone components included in its output are relatively large. SOLUTION: This string vibration detection sensor 10 is provided with a base body 11, permanent magnets 21 to 26 and magnetic sensing devices 31 and 32. The permanent magnets 21 to 26 are arranged and fixed to each corner part of two squares S1 and S2 adjacent to each other, so as to form a rectangle RT, the top faces of the permanent magnets 21, 23 and 25 are south poles, and the top faces of the permanent magnets 22, 24 and 26 are north poles. The magnetic sensing devices 31 and 32 are arranged at the centers of gravity of the squares S1 and S2 respectively, and their outputs are to be combined. Thus, an output of the sensor 10 vibrates, while having a frequency which is twice as high as that of a string ST, when the string ST vibrates within an x-y plane, and also, the waveform of the output becomes sharp to include a lot of overtone components to a fundamental tone components, when the string ST goes through over the permanent magnets 22 and 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a string vibration detecting sensor for detecting a vibration of a string of an electronic stringed instrument or the like by detecting a change in a magnetic field (magnetic field) formed by magnetic poles provided.

[0002]

2. Description of the Related Art Conventionally, the same polarity of two magnets (for example,
N poles) are opposed to each other to form a magnetic field, and a magnetically sensitive element such as a Hall element is arranged in a region of a zero magnetic field formed in the same magnetic field, and a change in the magnetic field caused by movement of a detection target is detected. 2. Description of the Related Art A sensor that detects the position and the like of an object to be detected by detecting with a magnetically sensitive element is known. In this conventional sensor, a magnetic field is formed with the same poles facing each other, so that one magnet generates a magnetic field in the opposite direction to the magnetic field generated by the other magnet. Therefore, even if the size of the magnetic charge of both magnets is increased, or both magnets are brought closer,
There has been a problem that the gradient of the magnetic field intensity (density of the lines of magnetic force) near the zero magnetic field region generated in the magnetic field formed by both magnets naturally has a limit, and as a result, the sensitivity of the sensor cannot be improved.

Therefore, as shown in FIG. 32, the applicant has arranged two north poles at corners on one diagonal of a square, and two south poles on another diagonal of the same square. Arranged at the corners, the magnetic sensing element G is arranged at the center of the square, and the string ST supported so as to be able to relatively oscillate with respect to these magnetic poles, the oscillation center of which is at the center line of the square. A sensor arranged so as to exist in a vertical plane has been proposed (Japanese Patent Application No. 2000-341021). According to this, the magnetic field generated from one magnetic pole is less likely to weaken the magnetic field generated from the other magnetic pole than the case where the same poles are opposed to each other, and the strength of the magnetic field near the magnetic field zero region formed by these magnetic poles is reduced. The gradient can be increased. As a result, the magnetic field formed by the N-pole and the S-pole greatly changes with respect to a change in the position of the string ST, which is a detection target, so that vibration of the same string can be detected with high sensitivity.

[0004]

However, according to the proposed string vibration detection sensor, as shown in FIG. 33, the period (frequency) of the string vibration and the period of the change of the magnetic field detected by the magnetic sensing element G ( Frequency) and the change in the magnetic field becomes sinusoidal, so that the fundamental tone component of the string is output larger than the harmonic component. For this reason, for example, when the string vibration detection sensor is replaced with a so-called analog pickup of an electric stringed instrument, and its output is amplified and sounded, there is a problem that a tone with a sense of incongruity becomes large.

[0005]

SUMMARY OF THE INVENTION A string vibration detection sensor according to the present invention addresses the above-mentioned problems, and is characterized in that the absolute value of the magnetic charge is reduced as shown in FIG. 1 which is a schematic perspective view. Magnetic poles (N-pole and S-pole) which are substantially equal to each other at the corners of two squares S1 and S2 which are in contact with each other so that the outer shape becomes a rectangle RT on the same plane, so that the polarities of magnetic poles adjacent to each other at the shortest distance are different. The string is supported so as to be capable of relative vibration with respect to the magnetic pole, and the vibration center is disposed so as to lie in a plane including a tangent of the two squares and being perpendicular to the plane, and the two squares are arranged. A magnetic sensitive element is arranged at each of the central portions of S1 and S2, and the outputs of the two magnetic sensitive elements are combined and output. In this case, the string is preferably a string of an electric stringed instrument.

FIG. 2 is a schematic plan view showing the relative positions of such a string vibration detection sensor and a string.
(A) → FIG. 2 (B) → FIG. 2 (A) → FIG. 2 (C) → FIG.
It vibrates as shown in FIG. FIG. 3A shows a square S which is a position at which the magnetically sensitive element is disposed due to the string vibration.
FIGS. 3A and 3B are graphs showing a change in the magnetic field at the center of S1 and S2 by a broken line and an alternate long and short dash line, respectively. FIG. 3B shows each output of the magnetically sensitive element and the above string obtained by combining the outputs of the magnetically sensitive element. The output of the vibration detection sensor is indicated by a broken line,
And a graph respectively showing the results by practice.

As is apparent from this graph, the output of the string vibration detection sensor has a period that is half the vibration period of the string ST (the frequency is twice the vibration frequency of the string ST). It shows a sharp change when passing through the position shown in FIG. Thereby, the ratio of the harmonic component to the fundamental component in the output of the string vibration detection sensor increases. Therefore, if the string vibration detection sensor is used for an electric stringed musical instrument and is configured to amplify the output of the sensor and emit a sound, it is possible to obtain a tone color with a small sense of incongruity in hearing.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a string vibration detection sensor according to the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a perspective view, FIG. 4 is a front view, and FIG. 5 is a plan view of a string vibration detection sensor 10 according to a first embodiment of the present invention. Magnet 2
1 to 26 and magnetically sensitive elements 31 and 32.

The base 11 is made of a material having high magnetic permeability such as permalloy, and has a rectangular shape having a short side and a long side along the x-axis and the y-axis, respectively, which are perpendicular to each other.
It is a thin plate having a thickness in the z-axis direction orthogonal to the axis.

Each of the permanent magnets 21 to 26 has the same magnetic charge, has the same cylindrical shape having a height in the z-axis direction, and is fixed to the upper surface of the base 11.
The center (magnetic pole) of the upper surface of each of the permanent magnets 21 to 26 is shown in FIG.
As shown in the figure, the shortest distance (square) is set at each corner of two squares S1 and S2 contacted on one side so as to form a rectangle RT having short sides and long sides along the x-axis and the y-axis, respectively. The magnetic poles adjacent to each other across the length of each side of S1 and S2, that is, the length of the short side of the rectangle RT, are arranged to be different from each other. In this example, the permanent magnets 21 and
The permanent magnets 3, 24, and 26 are disposed such that their upper surfaces become N poles. In addition, the shape of the permanent magnets 21 to 26 is not limited to a cylindrical shape.

As shown in FIGS. 1 and 5, the magnetically sensitive element 31 is disposed at the center of the square S1 (position near the center of gravity). This position is a region in the square S1 where the magnetic field generated by the magnetic poles formed by the permanent magnets 21, 22, 25, 26 is substantially zero. In addition, the magnetic sensitive element 3
As shown in FIG. 6, reference numeral 1 denotes a pair of magnetoresistive elements (hereinafter, referred to as GMR elements) 31a and 3 for obtaining a giant magnetoresistive effect by utilizing scattering depending on the spin direction of electrons.
1b and first to third three terminals 31c to 31e.

Each of the GMR elements 31a and 31b has a pinned layer whose magnetization direction is fixed (pinned), a free layer whose magnetization direction changes according to an external magnetic field, and is sandwiched between the pinned layer and the free layer. It is a well-known device having a conductive spacer layer, and is formed as a thin film having a predetermined pattern shape on the upper surface of the substrate S. These GMR elements 31a and 31b
The fixed magnetization directions of the pinned layers are fixed in the negative x-axis direction and the positive x-axis direction, respectively, as indicated by arrows in FIG. Both directions are in the negative y-axis direction (the direction orthogonal to the direction of the fixed magnetization of each of the pinned layers) in a state where they are not present. As shown in FIG. 7, each of the GMR elements 31a and 31b exhibits a different resistance value R depending on the angle θ between the fixed magnetization direction of the pinned layer and the magnetization direction of the free layer. When no external magnetic field is applied, they have the same resistance value R0.

As shown in FIGS. 1 and 5, the magnetically sensitive element 32 is disposed at the center of the square S2 (position near the center of gravity). This position is within the square S2, where the magnetic field generated by the magnetic poles formed by the permanent magnets 22, 23, 24, 25 is substantially zero. In addition, the magnetic sensitive element 3
2 are GMR elements 32a and 32b as shown in FIG.
And the first to third three terminals 32c to 32e, and have the same structure and the same function as the above-described magnetically sensitive element 31.

FIG. 8 is an equivalent circuit diagram of the string vibration detection sensor 10 using the magnetically sensitive elements 31 and 32. The arrows in the figure indicate the GMR elements 31a, 31b, 32a and 32b.
3 shows the fixed magnetization direction of the pinned layer. In this circuit, a constant voltage VB is applied to terminals 31c and 32e, and terminals 31e and 32c are grounded. G
A connection point P1 between the MR element 31a and the GMR element 31b is connected to an inverting amplification terminal of an operational amplifier 34 via a resistor 33 having a resistance value r1, and the GMR elements 32a and G
A connection point P2 of the MR element 32b is connected to a non-inverting amplification terminal of the operational amplifier 34 via a resistor 35 having a resistance value r1. The output terminal of the operational amplifier 34 and its inverting amplification terminal are connected via a resistor 36 having a resistance value r2, and the resistor 35 and the non-inverting input terminal of the operational amplifier 34 are grounded via a resistor 37 having a resistance value r2.

With this circuit, the operational amplifier 34 functions as a differential amplifier that amplifies and outputs the difference between the voltages at the inverting input terminal and the non-inverting input terminal, and its output Vout is connected to the connection point P.
1, when the potential of the connection point P2 is VP1 and VP2, respectively, it is expressed by the following equation (1). That is, the string vibration detection sensor 10 forms a full bridge circuit by the magnetically sensitive elements 31 and 32 each forming a half bridge circuit.

[0017]

## EQU1 ## Vout = (r2 / r1). (VP2-VP1)

The string ST is supported so as to be able to relatively vibrate with respect to the magnetic poles of the permanent magnets 21 to 26, and the position when the string ST is stationary, that is, the vibration center is the two squares S
It is arranged so as to include a tangent line of 1 and S2 (the center line in the longitudinal direction of the rectangle RT) and exist in a plane perpendicular to the xy plane.

Next, the operation of the string vibration detecting sensor 10 will be described, starting from the case where the string ST vibrates in the horizontal direction (vibrates in a plane parallel to the xy plane).

FIGS. 2A to 2C are schematic plan views of the string vibration detection sensor 10 and the string ST for indicating the relative positions of the string ST. FIG. FIG. 2B shows a state where the string ST vibrates and moves to the magnetically sensitive element 32 side, and FIG. 2C shows a state where the string ST vibrates and moves to the magnetically sensitive element 31 side. The state is shown. Hereinafter, the state shown in each of FIGS. 2A and 2B is expressed as the string ST being at the position (A), the position (B), and the position (C), respectively. According to this, the string ST vibrates in the order of position (A) → position (B) → position (A) → position (C) → position (A).

On the other hand, FIG. 3A shows the magnetically sensitive elements 31, 3
2 (A) to 2 (C) show the change in the magnetic field at the position of FIG.
It is the graph shown by the broken line L31 and the dashed-dotted line L32 according to the position of the string ST shown to (C), respectively. Note that FIG.
In (A), the downward direction (positive x-axis direction) in FIG. 2 is defined as the positive direction of the magnetic field. FIG. 3B shows the voltages VP1 and VP2 of the magnetically sensitive elements 31 and 32 as shown in FIGS.
3C is a graph showing the output voltage Vout of the string vibration detection sensor 10 as a solid line, as indicated by a dashed line and an alternate long and short dash line according to the position of the string ST shown in FIG.

First, when the string ST is at the position (A),
Since the lines of magnetic force from the magnet 22 to the magnet 25 pass through the string ST much, the density of the lines of magnetic force from the magnet 22 to the magnet 25 at the positions of the magnetically sensitive elements 31, 32 decreases. As a result, a strong magnetic field from the magnet 26 to the magnet 21 and from the magnet 24 to the magnet 23 appears at the positions of the magnetic sensing elements 31 and 32, respectively. Therefore, the downward magnetic field in FIG. It is larger than in some cases.

Next, when the string reaches the position (B), the magnet 22
Of the lines of magnetic force passing through the string ST from among the lines of magnetic force directed toward the magnet 25 from the position of the string ST at the position (A). The number increases. As a result, the magnetic field from the magnet 26 to the magnet 21 is weakened at the position of the magnetically sensitive element 31, so that the downward magnetic field at the same position is smaller than when the string ST is at the position (A). Also, at the position of the magnetically sensitive element 32, due to the presence of the string ST, the number of upward lines of magnetic force from the magnet 22 to the magnet 25 becomes larger than at the position of the magnetically sensitive element 31. As a result, the downward magnetic field at the position of the magnetically sensitive element 32 is smaller than the downward magnetic field at the position of the magnetically sensitive element 31.

Similarly, when the string reaches the position (C), the magnet 2
Since the number of lines of magnetic force passing through the string ST among the lines of magnetic force from 2 to the magnet 25 is smaller than when the string ST is at the position (A), the lines of magnetic force from the same magnet 22 toward the same magnet 25 at the position of the magnetically sensitive element 32 Increases. As a result, the magnetic field from the magnet 23 to the magnet 24 is weakened at the position of the magnetically sensitive element 32, so that the downward magnetic field at the same position is smaller than when the string ST is at the position (A). Further, at the position of the magnetically sensitive element 31, due to the presence of the string ST, the number of upward lines of magnetic force from the magnet 22 to the magnet 25 is larger than at the position of the magnetically sensitive element 32. As a result, the downward magnetic field at the position of the magnetically sensitive element 31 is smaller than the downward magnetic field at the position of the magnetically sensitive element 32.

Therefore, focusing on the magnetically sensitive element 31,
As shown in FIG. 3B, the voltage VP1 at the connection point P1 shown in FIG. 8 decreases as the downward magnetic field applied to the magneto-sensitive element 31 increases. Focusing on the magnetic sensitive element 32, the fixed layer of the GMR elements 32a and 32b is such that the voltage VP2 at the connection point P2 shown in FIG. 8 is applied to the magnetic sensitive element 32 as shown in FIG. It increases as the applied downward magnetic field increases. Then, the string vibration detection sensor 10
Output Vout is equal to voltage VP2 and voltage V
Since it is proportional to the difference of P1, as shown in FIG.
When the string ST passes through the position (A), it changes while having a sharp peak, and its oscillation period is half of the oscillation period of the string ST (string
Twice the ST vibration frequency). As a result, the output Vout of the string vibration detection sensor 10 becomes a signal containing a relatively large number of harmonic components with respect to the fundamental component.

Next, the operation of the string vibration detecting sensor 10 when the string ST vibrates in the vertical direction (vibrates in a plane parallel to the xz plane) will be described with reference to FIGS. 9 and 10. . FIG. 9 is a schematic front view of the string vibration detection sensor 10 and the string ST for indicating the relative position of the string ST.
The positions of the same string ST due to the vibration of are indicated by symbols X, Y, and Z. The position indicated by the symbol X (hereinafter, referred to as position X. The same applies to position Y and position Z) is the vibration center of the string ST, and the position Y and position Z are the string vibration detection sensor 1.
These are the lowest and highest positions of normal vibration as viewed from 0 (the base 11 of). That is, the string ST is represented by a position X → position Y → position X →
Vibrates like position Z → position X.

On the other hand, FIG.
The change of the magnetic field at the arrangement position of No. 32 is shown in FIG.
It is the graph shown by the curve L1 according to the position of ST.
In FIG. 10A, the downward direction (positive x-axis direction) in FIG. 2 is defined as the positive direction of the magnetic field. FIG.
(B) shows the voltages VP1 and VP2 of the magnetic sensing elements 31 and 32.
Are indicated by broken lines and alternate long and short dash lines according to the position of the string ST shown in FIG. 9, and the output voltage Vout of the string vibration detection sensor 10 is indicated by a solid line.

When the string ST moves from the position X to the position Y by vibration in the vertical direction, the lines of magnetic force from the magnet 22 passing through the string ST to the magnet 25 increase. Therefore, the lines of magnetic force from the magnet 22 to the magnet 25 at the positions of the magnetically sensitive elements 31 and 32 are reduced, and the magnets 26 to 21
Also, a magnetic field from the magnet 24 toward the magnet 23 appears strongly. As a result, as shown in FIG. 10A, the downward magnetic field in FIG. 2 increases at the positions of the magnetically sensitive elements 31 and 32.

On the other hand, when the string ST moves from the position X to the position Z due to the vertical vibration, the lines of magnetic force from the magnet 22 passing through the string ST to the magnet 25 decrease. Therefore, the line density of the magnetic force from the magnet 22 to the magnet 25 at the position of the magnetic sensing elements 31 and 32 increases, and the magnetic field from the magnet 26 to the magnet 21 and from the magnet 24 to the magnet 23 are canceled. As a result, at the positions of the magnetically sensitive elements 31 and 32, as shown in FIG.
The downward magnetic field in FIG. 2 is reduced.

Therefore, focusing on the magnetically sensitive element 31,
The voltage VP1 at the connection point P1 in FIG. 8 becomes minimum when the string ST is at the position Y and becomes maximum when the string ST is at the position Z, as shown in FIG. On the other hand, focusing on the magnetically sensitive element 32, the voltage VP2 at the connection point P2 in FIG. 8 becomes maximum when the string ST is at the position Y and minimum when the string ST is at the position Z, as shown in FIG. Become. Since the output Vout of the string vibration detection sensor 10 is proportional to the difference between the voltage VP2 and the voltage VP1 as shown in the above equation (1), as shown in FIG. It changes smoothly with the cycle. As described above, the string vibration detection sensor 10 can also detect the vertical vibration of the string ST. In the string vibration detection sensor of the present applicant shown in FIG. 32,
Because the change in the magnetic field due to the vertical oscillation of the string ST is small,
The component of the output of the vertical vibration of the same string ST with respect to the output of the horizontal vibration of the string ST is small, and as a result, the sound volume may not be sufficient depending on the picking direction of the string ST. Since a sufficient output can be obtained not only by the horizontal vibration of the string ST but also by the vertical vibration of the same string ST, a large volume can be obtained.

FIG. 11 is a graph showing the result of comparison between the output of the string vibration detecting sensor 10 and the output of another string vibration detecting sensor. FIG. 11A shows a single string used in a conventional electric stringed musical instrument. FIG. 11B shows a string vibration detection sensor of the present applicant shown in FIG. 32, and FIG. 11C shows a frequency component ratio (FFT) of the output of the string vibration detection sensor 10 by Fourier transform. Each is shown. In each drawing of FIG. 11, the horizontal axis “1” represents the frequency of the fundamental tone, and the horizontal axis “n” represents the frequency of the harmonic that is n times the frequency of the fundamental tone. As is apparent from FIG. 11, the output Vout of the string vibration detection sensor 10 includes a higher harmonic component ratio to the fundamental tone component than that of the string vibration detection sensor shown in FIG. 32, and the output of the conventional single coil pickup. And similar frequency characteristics.

As described above, the string vibration detection sensor 10 according to the first embodiment can obtain an output Vout containing a harmonic component appropriately with respect to the fundamental component based on the vibration of the string ST. If this is used as a string vibration pickup device of an electric stringed instrument, it is possible to obtain a tone with a little unpleasant audibility. Further, the string vibration detection sensor 10 can increase the magnetic field in the vicinity of the position where the magnetically sensitive elements 31 and 32 are provided without the magnetic poles formed by the permanent magnets 21 to 26 cancel each other out. ,
A slight change in the position of the string ST can be detected sensitively.
Further, since the sensor 10 uses a GMR element as a magnetically sensitive element, it is small in size, simple in structure, and can be manufactured at low cost.

(Second Embodiment) Next, a second embodiment of the string vibration detection sensor according to the present invention will be described. In the second embodiment, the string vibration detection sensor 10 is applied to a string vibration pickup device of an electric stringed instrument (in this example, an electric guitar).

More specifically, as shown in FIG. 12, the electric stringed instrument 40 has a wooden solid body 41.
And a neck 42 fixed to the body 41. A head 43 is integrally provided at an end of the neck 42, and a bridge 44 is provided on the body 41.
Are fixed, and between the head 43 and the bridge 44 are six steel strings (not shown) (not shown in FIG. 13).
1 to ST6). Further, the electric stringed musical instrument 40 includes a string vibration detection sensor 45.

FIG. 13 is a perspective view, FIG. 14 is a partial front view, and FIG. 1 is a plan view.
As shown in FIG. 5, a plurality of sensors having the same configuration (excluding the detection circuit) as the string vibration detection sensor 10 of the first embodiment are joined in parallel in the y-axis direction in the same direction, and 50, permanent magnets 51 to 66, and magnetically sensitive elements 71 to 77.

The base 50 is made of a high magnetic permeability material such as permalloy like the base 11, and has a rectangular shape having a short side and a long side along the x-axis and the y-axis which are orthogonal to each other. This is a thin plate member having a thickness in a z-axis direction orthogonal to the y-axis.

Each of the permanent magnets 51 to 66 has the same magnetic charge, has the same cylindrical shape with a height in the z-axis direction, and is fixed to the upper surface of the base 50.
The center (magnetic pole) of the upper surface of these permanent magnets 51 to 66 is
As shown in FIG. 15, a rectangle having a short side and a long side along the x-axis and the y-axis on the same plane, respectively.
The polarity of the magnetic poles adjacent to each corner of the seven squares Sq1 to Sq7 that are in contact so as to form RT1 with the shortest distance (the length of one side of the square length Sq1 to Sq7, the length of the short side of the square RT1) Are arranged differently from each other. Specifically, the upper surface of each of the permanent magnets 51, 53, 55, 57, 59, 61, 63, 65 becomes an S pole, and the permanent magnets 52, 54, 56, 5
The upper surfaces of 8, 60, 62, 64 and 66 are N poles.

Each of the magnetically sensitive elements 71 to 77 has a square Sq1.
To Sq7. This position is
The magnetic field generated by the magnetic poles formed by the four permanent magnets arranged at the respective corners of the squares Sq1 to Sq7 is a region where the magnetic field is substantially zero. The magnetically sensitive elements 71 to 77 have the same configuration as the magnetically sensitive element 31 shown in FIG.

The string vibration detecting sensor 45 includes strings ST1 to ST6.
When the electric stringed musical instrument 40 is not playing, the permanent magnets 52, 65, 53, 64, 54, 63, 55, 6
Upper surfaces of the permanent magnets 51 to 66 in a plane parallel to an xz plane including a line segment (each common side of the squares Sq1 to sSq7) connecting the central portions of 2, 56, 61, and 57, 60 It is arranged on the upper surface of the body 41 so as to pass through a position separated by a predetermined distance in the z-axis direction from a plane formed by the body 41.

FIG. 16 shows an equivalent circuit 80 of the string vibration detection sensor 45. In the figure, arrows attached to the magnetically sensitive elements 71 to 77 indicate a pair of GMs of the respective elements 71 to 77.
FIG. 9 schematically shows the direction of fixed magnetization of a fixed layer of an R element. That is, in FIG. 16, the arrows pointing right obliquely upward and obliquely right indicate the directions of magnetization of the pinned layer of the GMR element to which the arrows are directed upward (X-axis negative direction) and downward (X-axis positive direction) in FIG. Respectively.

As shown in FIG. 16, each pair of magnetically sensitive elements 71, 72, 73, 74, 75, 76
And the same full bridge circuits 81 to 83 as the circuit of the string vibration detection sensor 10 shown in FIG.
The magnetic sensitive element 77 forms a half bridge circuit 84 using fixed resistors 78 and 79, and the outputs of these circuits 81 to 84 are put together to generate the output Vout of the string vibration detection sensor 45. . Note that the resistors and the like shown in FIG. 16 are examples, and may be further added according to the required amplification factors of the circuits 81 to 84.

Next, the operation of the string vibration detection sensor 45 will be described. Each vibration of the strings ST1 to ST6 causes the magnetically sensitive elements 71,
72, 72, 73, 73, 74, 74, 75, 75, 7
6, 76, and 77, the converted voltage signals are amplified via the circuit circuits 81 to 84, then combined (superimposed), and output as an output Vout.

FIGS. 17 to 26 are graphs showing the results of comparison between the output of the string vibration detection sensor 45 and the outputs of other string vibration detection sensors. 17 to 21 and FIGS. 22 to 26 show that the vibrations of the third and fourth strings of the electric guitar are detected by various sensors, respectively, and the results are converted to the frequency component ratio by Fourier transform. (FFT).

Positions 1 and 2 in these figures mean components obtained when the down picking is performed substantially parallel to the fret surface at the positions indicated by the arrows in FIG. 27. . Also, in these figures,
"Single coil" refers to a conventional single coil pickup, "humbucking" refers to a conventional humbucking pickup, and "GMR sensor basic structure" refers to a string vibration detection sensor by the present applicant shown in FIG. , And “GMR sensor overtone adding structure” mean the string vibration detection sensor 45. Further, in these figures,
“Rear”, “center”, and “front” mean the arrangement positions of the respective sensors indicated by reference numerals RE, CN, and FR in FIG. In this example, the distance between the bridge Br and the front FR is 160 mm, the distance between the bridge Br and the center CN is 103 mm, and the distance between the bridge Br and the rear RE (the distance to the center position of the humbucking pickup) is 46 mm. The total length of the strings is 648 mm, and the frequencies when the third and fourth strings are opened are 196.00, respectively.
Hz and 146.83 Hz. The horizontal and vertical axes are shown in FIG.
Same as those of No. 1.

As shown in FIGS. 17 to 26, according to the string vibration detection sensor 45, the ratio of the harmonic component to the fundamental tone component is larger than that of the string vibration detection sensor shown in FIG. 32, and the frequency is similar to that of the conventional pickup. An output signal having characteristics was obtained. Therefore, even when the string vibration detection sensor 45 is used in place of an analog pickup of an electric guitar (a pickup that amplifies and emits sound as it is), it is possible to obtain a tone that is less uncomfortable in hearing. Moreover, since the magnetic poles formed by the permanent magnets 51 to 66 do not cancel each other out of the magnetic field and the magnetic field near the position where the magnetically sensitive elements 71 to 77 are provided can be increased, the string vibration detection sensor 45 , Small changes in the positions of the strings ST1 to ST6 can be detected sensitively. Further, since the sensor 45 uses the GMR element as the magnetically sensitive element, it is small in size, simple in structure, and can be manufactured at low cost.

(Modification) Next, FIG. 28 is a front view, and FIG.
Next, a modification of the first embodiment shown in a plan view and a side view in FIG. 30 will be described. The string vibration detection sensor 90 according to this modification can also be used as a string vibration detection sensor of an electric stringed instrument in the mode shown in the second embodiment.
Base 91, yokes 92-97, permanent magnets 98-100,
And the magnetically sensitive elements 101 and 102.

The base 91 is a thin plate having a rectangular shape having sides along the x-axis and the y-axis orthogonal to each other, and having a thickness in the z-axis direction orthogonal to the x-axis and the y-axis. Base 91
Is formed of a non-magnetic material unlike the base 11 of the first embodiment.

Each of the yokes 92 to 97 is made of a soft magnetic material and has the same cylindrical shape having a height in the z-axis direction. As shown in FIG. On the upper surface of the base 91, the two squares S1 and S2 are arranged so as to coincide with the corners of the two squares S1 and S2 contacted to form a rectangle RT having a short side and a long side along the x-axis and the y-axis, respectively. It is fixed.

The yokes 92 to 97 have pole pieces 92a to 97a made of a soft magnetic material at their upper portions, respectively. Each of the pole pieces 92a to 97a includes an upper portion having a substantially disk shape, and a column extending downward from the upper portion. A screw is formed on the outer periphery of each column, and the screw is screwed with a screw (not shown) formed on the inner periphery of the yokes 92 to 97. Accordingly, the height (the height in the z-axis direction) of the pole pieces 92a to 97a with respect to the base 91 can be changed.

The substantially quadrangular prism-shaped permanent magnets 98 to 100 are
They are arranged between the yokes 92 and 97, between the yokes 93 and 96, and between the yokes 94 and 95, respectively, and are fixed to the upper surface of the base 91. The permanent magnets 98 to 100 include yokes 92 and 97, yokes 93 and 96, and yokes 94,
95 and are respectively magnetically coupled to the yokes 92,
94, 96 and yokes 93, 95, 97
An S-pole and an N-pole respectively appear.

The magnetic sensitive elements 101 and 102 are the same as the magnetic sensitive elements 31 and 32 of the first embodiment.
The positional relationship between the string ST, which is the detection target, and the sensor 90 is the same as the positional relationship between the string ST and the string vibration detection sensor 10 in the first embodiment.

The sensor 90 configured as described above has a first
Acts similarly to the string vibration detection sensor 10 according to the embodiment,
An output having a high ratio of the harmonic component to the fundamental component is generated. The string vibration detection sensor 90 can be manufactured at low cost because it requires only three permanent magnets. In addition, pole piece 9
Adjusting the height of 2a to 97a also has the advantage that sensitivity can be adjusted.

As described above, the string vibration detection sensor according to each of the above-described embodiments and modifications according to the present invention can generate an output appropriately including a fundamental component and a harmonic component based on the string vibration. . Note that the present invention is not limited to the above embodiments and modified examples, and includes various modified examples within the scope of the present invention. For example, the magnetically sensitive elements 31 and 32 in the first embodiment form a half bridge circuit composed of a pair of GMR elements 31a, 31b, 32a and 32b, but the GMR element 31a and the GMR element 32b or the GMR element 31b. And the GMR element 32a may be magnetically shielded, or may be constituted only by a single GMR element.

Further, the magnetically sensitive element 31 (32)
As shown in FIG. 1, the four GMR elements 31f to 31i
(32f-32i) to form a full bridge circuit,
The output Vout31 (Vout32) may be extracted, and the output voltages Vout31 and Vout32 may be combined (added) to obtain the output Vout of the string vibration detection sensor 10.
In this case, the GMR elements 31f to 31i (32f to 32
The direction of magnetization of each pinned layer in i) is as shown by the arrow in FIG.

Further, the magnetically responsive element of each of the above embodiments is G
Although it was constituted by an MR element, a Hall element, an MR element, a TMR element utilizing a magnetic tunnel effect, an MI (Ma
gnetic Impedance) sensor or pickup coil. In addition, in each of the above embodiments, the magnetic field is formed by the permanent magnet, but the magnetic field may be formed by the electromagnet. Further, the string vibration detection sensor according to the present invention is not limited to an electric guitar,
It can also be used as a string vibration detection sensor for musical instruments using strings such as violin, cello, bass, mandolin, and piano.

[Brief description of the drawings]

FIG. 1 is a perspective view of a string vibration detection sensor according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view of the sensor shown in FIG. 1 showing a relative positional relationship between the sensor and a string.

3A is a graph showing a change in a magnetic field at a place where the magnetic sensing element shown in FIG. 1 is provided with respect to horizontal vibration of a string, and FIG. 3B is a graph showing each magnetic sensitive element with respect to vibration of the same string; FIG. 4 is a diagram showing a voltage indicated by a symbol and an output voltage of a string vibration detection sensor.

FIG. 4 is a front view of the string vibration detection sensor shown in FIG.

FIG. 5 is a plan view of the string vibration detection sensor shown in FIG.

FIG. 6 is an enlarged plan view of a magnetic sensing element (GMR element) of the string vibration detection sensor shown in FIG.

FIG. 7 is a characteristic diagram of each magnetically sensitive element shown in FIG.

FIG. 8 is a circuit diagram of the string vibration detection sensor shown in FIG.

FIG. 9 is a schematic front view showing a relative positional relationship between the sensor shown in FIG. 1 and a string.

FIG. 10 (A) shows FIG. 1 with respect to vertical vibration of a string.
3B is a graph showing a change in a magnetic field at a place where the magnetically sensitive element shown in FIG. 1 is disposed, and FIG. 2B is a diagram showing a voltage of each magnetically sensitive element with respect to vibration of the same string and an output voltage of a string vibration detection sensor. .

11A is a single-coil pickup used in a conventional electric stringed musical instrument, FIG. 11B is a string vibration detection sensor shown in FIG. 32, and FIG. 11C is an output of the string vibration detection sensor shown in FIG. 6 is a graph showing a frequency component ratio by Fourier transform of FIG.

FIG. 12A is a front view of an electric stringed instrument to which the string vibration detection sensor according to the second embodiment of the present invention is applied,
(B) is a side view of the electric stringed instrument.

FIG. 13 is a perspective view of a string vibration detection sensor according to a second embodiment of the present invention.

FIG. 14 is a partial front view of the string vibration detection sensor shown in FIG.

FIG. 15 is a plan view of the string vibration detection sensor shown in FIG.

FIG. 16 is a circuit diagram of the string vibration detection sensor shown in FIG.

FIG. 17 is a graph showing a frequency analysis result of a signal obtained by detecting the vibration of the third string of the electric guitar at the front position of the guitar with a conventional single-coil pickup.

FIG. 18 is a graph showing a frequency analysis result of a signal obtained by detecting the vibration of the third string of the electric guitar at the center position of the guitar with a conventional single-coil pickup.

FIG. 19 is a graph showing a frequency analysis result of a signal obtained by detecting the vibration of the third string of the electric guitar at the rear position of the guitar using a conventional humbucking pickup.

20 is a graph showing a frequency analysis result of a signal obtained by detecting the vibration of the third string of the electric guitar at the rear position of the guitar by the string vibration detection sensor shown in FIG. 32.

21 is a graph showing a frequency analysis result of a signal obtained by detecting the vibration of the third string of the electric guitar at the rear position of the guitar by the string vibration detection sensor shown in FIG.

FIG. 22 is a graph showing a frequency analysis result of a signal obtained by detecting the vibration of the fourth string of the electric guitar at the front position of the guitar with a conventional single-coil pickup.

FIG. 23 is a graph showing a frequency analysis result of a signal obtained by detecting the vibration of the fourth string of the electric guitar at the center position of the guitar with a conventional single-coil pickup.

FIG. 24 is a graph showing a frequency analysis result of a signal obtained by detecting the vibration of the fourth string of the electric guitar at the rear position of the guitar using a conventional humbucking pickup.

FIG. 25 is a graph showing a frequency analysis result of a signal obtained by detecting the vibration of the fourth string of the electric guitar at the rear position of the guitar by the string vibration detection sensor shown in FIG. 32;

26 is a graph showing a frequency analysis result of a signal obtained by detecting the vibration of the fourth string of the electric guitar at the rear position of the guitar by the string vibration detection sensor shown in FIG.

FIG. 27 is a partial front view of the electric guitar for explaining the measurement conditions of the results shown in FIGS. 17 to 26;

FIG. 28 is a front view of a modification of the string vibration detection sensor according to the present invention shown in FIG. 1;

FIG. 29 is a plan view of the string vibration detection sensor shown in FIG. 28.

FIG. 30 is a side view of the string vibration detection sensor shown in FIG. 28.

FIG. 31 is an equivalent circuit diagram showing a modification of the magnetic sensing element of the string vibration detection sensor shown in FIG.

FIG. 32 is a perspective view of a string vibration detection sensor according to a prior application proposed by the present applicant.

33A is a schematic front view showing a relative positional relationship between the sensor and the string shown in FIG. 32, and FIG. 33B is a view at a place where the magnetically sensitive element shown in FIG. 5 is a graph showing a change in a magnetic field.

[Explanation of symbols]

10, 45, 90 ... string vibration detection sensor, 11, 50, 9
DESCRIPTION OF SYMBOLS 1 ... Substrate, 21-26, 51-66, 98-100 ... Permanent magnet, 31, 32, 71-77, 101, 102 ... Magnetically sensitive element, 40 ... Electric stringed instrument, 92-97 ... Yoke,
ST, ST1 to ST6 ... strings.

Claims (2)

[Claims] A magnetic pole having substantially the same absolute value of a magnetic charge is attached to each corner of two squares that are in contact with each other so that the outer shape is rectangular on the same plane, so that the polarities of magnetic poles adjacent to each other at the shortest distance are different. Arranging and arranging the strings supported so as to be able to vibrate relative to the magnetic pole such that the center of vibration is in a plane that includes the two square tangents and is perpendicular to the plane,
A string vibration detection sensor in which a magnetically sensitive element is disposed at the center of each of the two squares, and the outputs of the two magnetically sensitive elements are combined and output. 2. The string vibration detection sensor according to claim 1, wherein the string is a string used for an electric stringed musical instrument.