Provided is a capo that can be operated simply and reliably. A capo includes a pair of arm members (a first arm member and a second arm member) capable of sandwiching a neck, and an electric drive mechanism that changes a distance between the pair of arm members.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a capo that is an article for use in pitch adjustment when performing a stringed instrument such as a guitar.

2. Description of the Related Art

A capo is for use in pressing desired positions of all strings of a stringed instrument such as a guitar. In case of accompanying a song on the stringed instrument, the positions to be pressed with the capo are changed in accordance with a tune or a singing range of a singer. On stage, however, it is necessary to rapidly operate the capo without making any sound, between tunes and so on.

Conventional capos include, for example, a type of capo that holds a neck of the stringed instrument to press all strings by use of spring force. Furthermore, there are other types of capos such as a capo which is tightened with grip strength to hold the neck with frictional force (e.g., see International Publication No. WO 2009/115461, hereinafter referred to as “PTL 1”) and a capo which utilizes leverage (e.g., see International Publication No. WO 98/49669 and Japanese Patent Application Laid-Open No. 2010-145998, hereinafter respectively referred to as “PTL 2” and “PTL 3”).

CITATION LIST

SUMMARY OF THE INVENTION

However, when a type of capo which uses a spring or friction to hold the neck is attached, strong grip strength is required. It is difficult especially for a player with insufficient grip strength to rapidly operate the capo, for example, between performances. Furthermore, a type of capo which utilizes leverage can be operated with light force. However, it is required to adjust beforehand in accordance with the stringed instrument, and is difficult to adjust the capo so as to be usable for a plurality of stringed instruments at once.

The present invention has been made in view of such situations, and aims to provide a capo that can be operated simply and reliably even by a player with insufficient grip strength.

To achieve the above object, provided are aspects of the present invention as follows.

A capo according to a first aspect of the present invention is a capo which is to be fixed onto a neck of a stringed instrument, including: a pair of arm members (a pair of arm) configured to hold the neck therebetween; and an electric drive mechanism (electric driver) configured to change a distance between the pair of arm members.

According to a second aspect of the present invention, in the capo according to the first aspect, one arm member of the pair of arm members is a movable arm member, and the other arm member is a non-movable arm member, and the electric drive mechanism includes: a motor configured to generate a drive force; and a drive force transmission member configured to transmit the drive force generated by the motor to the movable arm member.

According to a third aspect of the present invention, in the capo according to the second aspect, the drive force transmission member (drive force transmission) is a lead screw to be rotated by the motor, and the movable arm member includes a screw part (screw-formed part) having a screw hole into which the lead screw is screwed, and the movable arm member is configured to be movable in an axial direction of the lead screw by rotation of the lead screw.

According to a fourth aspect of the present invention, in the capo according to the second aspect, the drive force transmission member is a worm gear including: a worm coupled to an output shaft of the motor; and a worm wheel configured to mesh with the worm, and the movable arm member is coupled and fixed to the worm wheel.

According to a fifth aspect of the present invention, the capo according to any one aspect of the second aspect to the fourth aspect, includes: a voltmeter configured to measure a voltage applied to the motor; and a first motor controller configured to permit bidirectional rotation of the motor in a case where the voltage is more than or equal to a first threshold, and configured to permit only unidirectional rotation of the motor in a case where the voltage is less than the first threshold.

According to a sixth aspect of the present invention, the capo according to any one aspect of the second aspect to the fifth aspect, includes: an ammeter configured to measure a current flowing through the motor, and a second motor controller configured to prohibit rotation of the motor in a case where the current is more than or equal to a second threshold, and configured to permit the rotation of the motor in a case where the current is less than the second threshold.

According to the present invention, a distance between a pair of arm members can be adjusted easily and simply by an electric drive mechanism, and hence a player with insufficient grip strength can also operate simply and reliably.

DESCRIPTION OF EMBODIMENTS

Hereinafter, description will be made as to preferable embodiments according to the present invention in detail with reference to the accompanying drawings.

First Embodiment

FIG. 1is a schematic view showing a configuration of a capo10according to a first embodiment. As shown inFIG. 1, the capo10of the present embodiment includes a first arm member12and a second arm member14disposed opposite to each other, as a pair of arm members capable of holding a neck50of a stringed instrument therebetween. The first arm member12is disposed on a front surface side (a side where strings52are disposed) of the neck50. The second arm member14is disposed on a back surface side (a side opposite to the side where the strings52are disposed) of the neck50.

The capo10according to the present embodiment further includes an electric drive mechanism16configured to change a distance (space) between the first arm member12and the second arm member14. The electric drive mechanism16includes a motor18that is a drive source, and causes the first arm member12to move closer to or away from the second arm member14(an opening/closing operation) by use of a drive force generated by the motor18, so as to change the distance between the first arm member12and the second arm member14.

The motor18is fixed to the second arm member14that is a non-movable arm member, and generates the drive force to move the first arm member12relative to the second arm member14. The motor18is an electric motor that is capable of bidirectionally rotating its output shaft (a rotary shaft).

The motor18is electrically connected to a battery20and an operation unit22that are provided in the second arm member14. The operation unit22includes a plurality of switches28A to28D (seeFIG. 2) as described later. In response to an operation state (an on/off state) of each of these switches28A to28D, a current is supplied from the battery20to the motor18. Consequently, the motor18generates the drive force depending on the current supplied from the battery20.

Furthermore, the electric drive mechanism16includes a lead screw24that transmits, to the first arm member12, the drive force generated by the motor18. The lead screw24is an example of a drive force transmission member of the present invention.

The lead screw24is coupled to the output shaft of the motor18, and rotates integrally with the output shaft of the motor18. On a surface (a circumferential surface) of the lead screw24, a screw thread (an external thread) is formed.

The first arm member12includes a screw part (a nut part)26having a screw hole (an internal thread) into which the lead screw24is screwed, and is configured to be movable in an axial direction of the lead screw24by rotation of the lead screw24. Note that to convert the rotation of the lead screw24to linear movement of the first arm member12, the capo10is provided with a rotation regulating unit (not shown) that regulates rotation of the first arm member12in rotating the lead screw24.

According to such a configuration, when the lead screw24is rotated by the drive force generated by the motor18, the first arm member12moves in the axial direction of the lead screw24. That is, depending on a rotating direction of the screw, the first arm member12performs the opening/closing operation of moving on a direction approaching the second arm member14(a downward direction ofFIG. 1) or a direction separating from the second arm member14(an upward direction ofFIG. 1).

FIG. 2is a circuit diagram showing an electric configuration of the electric drive mechanism16of the capo10according to the first embodiment.

As shown inFIG. 2, the electric drive mechanism16of the capo10according to the present embodiment includes the plurality of switches28A to28D as components of the operation unit22described above (seeFIG. 1). The electric drive mechanism16is formed as a general H-bridge circuit by the plurality of switches28A to28D, and controls increase/decrease of the current that flows through a coil of the motor18in accordance with any combination of the on/off states of the respective switches28A to28D. Note that each of the switches28A to28D may be a mechanical contact switch or a semiconductor switch.

There are three modes of control of the current that flows through the coil of the motor18. That is, when a first switch28A and a fourth switch28D are turned on among the respective switches28A to28D, the control mode turns to a forward rotation mode where the motor18rotates forward. Furthermore, when a second switch28B and a third switch28C are turned on, the control mode turns to a reverse rotation mode where the motor18rotates in reverse. Alternatively, when the first switch28A and the second switch28B are turned on or the third switch28C and the fourth switch28D are turned on, the control mode turns to a stop mode where a braking brake of the motor18is operated.

Next, an operation in attaching the capo10according to the present embodiment to the neck50will be described.

First, in a case where the distance between the first arm member12and the second arm member14decreases, the second switch28B and the third switch28C are turned on by an operation of the operation unit22, and the motor18is driven in the reverse rotation mode to broaden the distance between the first arm member12and the second arm member14. Consequently, the capo10is placed in an open state so that the capo can be attached to the neck50.

Next, in a case where the capo10is attached to the neck50, in order to fix the capo10at a desired pitch position, the capo10is positioned with the neck50in a state where the neck50and the strings52are disposed between the first arm member12and the second arm member14.

Next, the operation unit22is operated to turn on the first switch28A and the fourth switch28D, and the motor18is driven in the forward rotation mode to gradually decrease the distance between the first arm member12and the second arm member14. Consequently, the neck50and the strings52are held (sandwiched) between the first arm member12and the second arm member14, and the capo10is in a fixed state where the capo10is unremovably fixed to the neck50.

Consequently, when the capo10is attached to the neck50(i.e., in the above fixed state), the operation unit22is preferably operated to turn on the first switch28A and the second switch28B or turn on the third switch28C and the fourth switch28D in order to set the motor18in the stop mode. In such a state, the braking brake of the motor18is operated. to keep the distance between the first arm member12and the second arm member14. According to this aspect, the capo10attached to the neck50can be prevented from being loosened during performance with the stringed instrument.

Note that to remove the capo10according to the present embodiment from the neck50, the operation unit22is operated to turn on the second switch28B and the third switch28C in order to drive the motor18in the reverse rotation mode and broaden the distance between the first arm member12and the second arm member14. Consequently, the capo10can be easily removed from the neck50.

As above, according to the first embodiment, the electric drive mechanism16can easily and simply adjust the distance between the first arm member12and the second arm member14. The electric drive mechanism16can selectively switch the capo10between the fixed state where the capo10is fixed to be unremovable from the neck50and the open state where the capo10is attachable to and removable from the neck50. Therefore, even a player with insufficient grip strength can operate simply and reliably.

Note that in the explanation about the configuration of the first embodiment, the first arm member12is a movable arm member and the second arm member14is a non-movable arm member, but these members may be configured in reverse.

Furthermore, in the first embodiment, the capo10is configured to be able to open and close by the electric operation, but the capo10may be configured to be able to open and close by a manual operation, in addition to the electric operation.

FIG. 3is a schematic view showing a modification of the configuration of the capo10according to the first embodiment. In the modification shown inFIG. 3, the capo10further includes a knob30that is a manual operation member, in addition to the configuration shown inFIG. 1. The knob30is attached to a tip of the lead screw24. Further, the knob30may be detachably attached to the lead screw24. Consequently, even in case of battery exhaustion, the knob30attached to the tip of the lead screw24can be operated to rotate so that the lead screw24can be rotated. Thus, it is possible to perform the opening/closing operation of changing the distance between the first arm member12and the second arm member14. Therefore, even in a case where the battery20is exhausted in a state where capo10is attached to the neck50of the stringed instrument, the capo10is removable from the neck50. Furthermore, if a tightening force of the capo10to the neck50is insufficient, the capo10can be tightened with a manual operation by use of the knob30.

Note that the present invention is not limited to the configuration where the manual operation is performed by use of the knob30. The manual operation may be performed using a general tool such as a driver or a hexagonal wrench.

Second Embodiment

Next, description will be made as to a second embodiment according to the present invention. Hereinafter, description of parts common to that of the first embodiment is omitted, and characteristic parts of the present embodiment will be mainly described.

The second embodiment is similar to the first embodiment except a different electric configuration of the capo10.

FIG. 4is a circuit diagram showing an electric configuration of an electric drive mechanism16of the capo10according to the second embodiment. Here, inFIG. 4, a component common or similar to that ofFIG. 2is denoted with the same reference number.

As shown inFIG. 4, the electric drive mechanism16in the second embodiment further includes a voltmeter32, an ammeter34, and a microcomputer36, in addition to the configuration of the first embodiment.

The voltmeter32measures a voltage (a power supply voltage) to be applied to a motor18. The voltage measured by the voltmeter32is output to the microcomputer36. Note that accurately, the output of the voltmeter32is converted to a digital signal by an A/D converter or the like, and then output to the microcomputer36.

The ammeter34measures a current (a load current) to be supplied to the motor18. The current measured by the ammeter34is output to the microcomputer36. Note that accurately, the output of the ammeter34is converted to a voltage value at a shunt resistance or the like, converted to a digital signal by the A/D converter or the like, and output to the microcomputer36.

The microcomputer36includes a known configuration including a CPU, a ROM, a RAM, an input/output interface and others. The microcomputer36is connected to the voltmeter32, the ammeter34, and the motor18. According to computer program stored in the ROM, the microcomputer functions as a first motor controller38that controls an operation of the motor18depending on the voltage measured by the voltmeter32, and functions as a second motor controller40that controls the operation of the motor18depending on the current measured by the ammeter34.

The first motor controller38determines whether the voltage measured by the voltmeter32is more than or equal to a preset first threshold. The first threshold may be held in storage device such as the RAM. The first threshold may be a value obtained by multiplying a maximum voltage value of a battery20by a predetermined coefficient (e.g., from 0.1 to 0.3).

In a case where it is determined that the voltage measured by the voltmeter32is more than or equal to the first threshold, the first motor controller38determines that the battery20has a sufficient remaining amount of power, and permits operations of the motor18both in the forward rotation mode and in the reverse rotation mode. That is, the first motor controller38permits bidirectional rotation of the motor18, and enables both an opening operation of moving the first arm member12apart from the second arm member14and a closing operation of moving the first arm member12closer to the second arm member, as the opening and closing operations of the first arm member12and the second arm member14of the capo10.

On the other hand, if the voltage measured by the voltmeter32is less than the first threshold, the first motor controller38determines that the battery20only has a small remaining amount of power, and permits only the operation of the motor18in the reverse rotation mode. That is, the first motor controller38permits only unidirectional rotation of the motor18, and enables only the opening operation of moving the first arm member12apart from the second arm member14, in the opening and closing operations of the first arm member12and the second arm member14of the capo10. The first motor controller38does not permit the closing operation of moving the first arm member12closer to the second arm member14.

The second motor controller40determines whether the current measured by the ammeter34is more than or equal to a preset second threshold. The second threshold may be held in storage device such as the RAM. The second threshold may be a value obtained by multiplying a maximum load current value of the motor18by a predetermined coefficient (e.g., from 0.8 to 0.9).

In a case where it is determined that the current measured by the ammeter34is less than the second threshold, the second motor controller40determines that the current to be supplied to the motor18is in a normal range, and permits rotation of the motor18. On the other hand, if the current measured by the ammeter34is more than or equal to the second threshold, the second motor controller40determines that the current to be supplied to the motor18is excessively beyond the normal range, and prohibits the rotation of the motor18to stop the operation of the motor18. Furthermore, in a case where the capo10moves in an open direction (a direction in which the first arm member12and the second arm member14move apart from each other), it is also possible to automatically stop the motor18at an open limit.

As above, according to the second embodiment, in a case where the battery20has the small remaining amount of power, the motor18is controlled so as to move only in the direction in which the capo10opens. Consequently, the battery20can be prevented from being exhausted in a state where the capo10is attached to a neck50of a stringed instrument, and the capo10can be prevented from becoming unremovable from the neck50.

Furthermore, according to the second embodiment, in a case where the load current of the motor18is excessively large, the operation of the motor18is stopped. Consequently, when the capo10is attached to the neck50, the neck50held between the first arm member12and the second arm member14is not tightened with an excessively large force. Therefore, the neck50can be prevented from being damaged, and the player's hand or the like can be prevented from being caught.

Note that in the second embodiment, explanation is made for the configuration where the operation of the motor18is controlled by using the microcomputer36, but the present invention is not limited to this configuration. The cap10can be configured such that, for example, a comparator or the like is used in place of the microcomputer36.

Third Embodiment

Next, description will be made as to a third embodiment according to the present invention. Hereinafter, description of parts common to that of each of the above described embodiments is omitted, and characteristic parts of the present embodiment will be mainly described.

The third embodiment is similar to the first embodiment except a different mechanical configuration of the capo10.

FIG. 5is a schematic view showing a configuration of the capo10according to the third embodiment. Here, inFIG. 5, components common or similar to that ofFIG. 1are denoted with the same reference numbers.

As shown inFIG. 5, the capo10according to the third embodiment includes a worm gear (a reduction mechanism) having a worm42and a worm wheel44. The worm gear is an example of a drive force transmission member according to the present invention.

The worm42is a screw-like gear having a spiral groove formed in a circumferential surface thereof. The worm42is coupled to the output shaft of the motor18, and rotates integrally with the output shaft of the motor18.

The worm wheel44is a semicircular worm wheel (a bevel gear) configured to mesh with the worm42. The worm wheel44is supported by the second arm member14so as to be rotatable about (around) a wheel shaft46. Furthermore, the first arm member12is coupled and fixed to the worm wheel44.

With the configuration, when the worm42is rotated by a drive force generated by the motor18, the worm wheel44which is rotatably supported by the second arm member14rotates about the wheel shaft46according to a rotating direction of the worm42. Consequently, the first arm member12rotates integrally with the worm wheel44about the wheel shaft46. Therefore, the first arm member12performs the opening/closing operation of moving in a direction approaching to the second arm member14or a direction separating from the second arm member14.

Therefore, according to the third embodiment, similarly to the above described first embodiment, the electric drive mechanism16can easily and simply adjust the distance between the first arm member12and the second arm member14, and can selectively switch the capo10between the fixed state where the capo10is unremovably fixed to the neck50and the open state where the capo10is attachable to and removable from the neck50.

Furthermore, according to the third embodiment, the distance between the first arm member12and the second arm member14can be kept (maintained) by a self-lock (automatic tightening) function of the worm gear having the worm42and the worm wheel44without using a braking brake of the motor18.

Note that in the third embodiment, the explanation is made for the configuration provided with the worm gear having the worm42and the worm wheel44as the drive force transmission member, but the present invention is not limited to this configuration. The capo10may be configured to include various types of gears.

Additionally, needless to say, as an electric configuration of the capo10in the third embodiment, a configuration similar to that of the first embodiment or the second embodiment is applicable.

Furthermore, in the third embodiment, the capo10is configured to be openable and closable by an electric operation, but similarly to the modification of the first embodiment, the capo10may be further configured to be openable and closable by a manual operation in addition to the electric operation.

FIG. 6is a schematic view showing a modification of the configuration of the capo10according to the third embodiment. In the modification shown inFIG. 6, the capo further includes a knob48that is a manual operation member, in addition to the configuration shown inFIG. 5. The knob48is attached to a tip of the worm42. The knob48may be detachably attached to and removed from the worm42. Consequently, similarly to the modification of the first embodiment, even in case of battery exhaustion, the knob48attached to the tip of the worm42is operated to rotate so that the worm42is rotated. Thereby, it is possible to perform the opening/closing operation of changing the distance between the first arm member12and the second arm member. Therefore, even in a case where the battery20is exhausted in a capo10attached to a neck50of a stringed instrument, the capo10can be removed from the neck50. Furthermore, if the tightening force of the capo10to the neck50is insufficient, the knob48is manually operated so that the capo10can be tightened.

Note that in each of the above described embodiments, explanation is made for the configuration having the motor18, as the electric drive mechanism16of the capo10. However, the present invention is not limited to the configuration. For example, the capo10may be configured to include a piezoelectric actuator or an artificial muscle actuator that expands and contracts by applying the voltage.

FIG. 7is a schematic view showing a configuration example where a piezoelectric actuator64is used as the electric drive mechanism16of the capo10. Here, inFIG. 7, components common or similar to that ofFIG. 1orFIG. 5are denoted with the same reference numbers.

In the configuration example shown inFIG. 7, the first arm member12and the second arm member14form a pair of arm members, and can hold the neck50of a stringed instrument therebetween. The first arm member12and the second arm member14respectively have shaft holes, and a rotary shaft60such as a pin is inserted into the shaft holes so that the first arm member12and the second arm member14are rotatably coupled to each other.

An urging member62such as a spring is provided between the first arm member12and the second arm member14. The urging member62has two ends that are respectively fixed to the first arm member12and the second arm member14, to generate an urging force in a direction in which the first arm member12and the second arm member14are urged to move close to each other. Consequently, in a case where the piezoelectric actuator64described later is not driven, the urging force of the urging member62always urges the first arm member12and the second arm member14to a state where the first arm member12and the second arm member14are approaching to each other (i.e., the state corresponding to the fixed state above). Therefore, the urging force of the urging member62is suitably adjusted so as to adjust a force to press the strings52against the neck50of the stringed instrument. In consequence, a tone obtained when the capo10is attached to the neck50of the stringed instrument can be adjusted with the urging force of the urging member62.

Furthermore, in the configuration example shown inFIG. 7, the piezoelectric actuator64is disposed between the first arm member12and the second arm member14, more specifically at a position closer to the rotary shaft60than to the urging member62(preferably a position near the rotary shaft60). The piezoelectric actuator64is an actuator that is stretched (stretched in a vertical direction inFIG. 7) by applying a voltage. Therefore, when the voltage is applied to the piezoelectric actuator64by an actuator drive unit (not shown), the piezoelectric actuator64stretches, to perform an opening operation which causes the first arm member12and the second arm member14to separate from each other against the urging force of the urging member62.

According to the configuration example shown inFIG. 7, between the opening operation and the closing operation that change the distance between the first arm member12and the second arm member14, the piezoelectric actuator64is driven only when the opening operation is performed. Therefore, power consumption can be suppressed.

Furthermore, according to the configuration example shown inFIG. 7, the piezoelectric actuator64is disposed closer to the rotary shaft60than to the urging member62. Consequently, even in a case where the piezoelectric actuator64has a small stretching rate (expansion/contraction rate), it is possible to broaden a drive range (an opening/closing range) of the first arm member12and the second arm member14, using the principle of leverage.

FIG. 8is a schematic view showing a configuration example where an artificial muscle actuator66is used as an electric drive mechanism16of the capo10. Here, inFIG. 8, components common or similar to that ofFIG. 7are denoted with the same reference numbers.

In the configuration example shown inFIG. 8, a basic configuration is similar to that in the configuration example shown inFIG. 7, but in place of the piezoelectric actuator64(e.g., seeFIG. 7), the artificial muscle actuator66is provided. Note that the urging member62generates an urging force in a direction in which a first arm member12and a second arm member14are moved close to each other in the same manner as in the configuration example shown inFIG. 7.

The artificial muscle actuator66is an actuator contracted (contracted in the vertical direction inFIG. 8) by applying a voltage. The artificial muscle actuator66is common to the piezoelectric actuator64shown inFIG. 7in that the artificial muscle actuator66is disposed between the first arm member12and the second arm member14. However, the artificial muscle actuator66is different in that the artificial muscle actuator66is disposed at a position not on the same side as an urging member62relative to the rotary shaft60, but on a side opposite to the urging member relative to the rotary shaft60.

Therefore, according to the configuration example shown inFIG. 8, in a case where the voltage is applied to the artificial muscle actuator66by an unshown actuator drive unit, the artificial muscle actuator66contracts so as to perform the opening operation of causing the first arm member12and the second arm member14to move away from each other against the urging force of the urging member62.

Furthermore, it is preferable that a distance between the artificial muscle actuator66and the rotary shaft60is shorter than a distance between the urging member62and the rotary shaft60. According to this configuration, in the same manner as in the configuration example shown inFIG. 7, even in a case where the artificial muscle actuator66has a small ratio of expansion and contraction, it is possible to broaden a drive range (an opening/closing range) of the first arm member12and the second arm member14with a principle of leverage.

Note that in the respective configuration examples shown inFIG. 7andFIG. 8, it is also possible to configure the capo10such that the piezoelectric actuator64is replaced with the artificial muscle actuator66and an urging direction of the urging member62is reversed (i.e., a direction of moving the first arm member12and the second arm member14away from each other). In this case, however, the configuration is disadvantageous in terms of power consumption because a force to hold the neck50between the first arm member12and the second arm member14is applied with the actuator (the piezoelectric actuator64or the artificial muscle actuator66). Consequently, the configuration where the urging member62urges the first arm member12and the second arm member14in a direction approaching to each other is preferable as in the configuration examples shown inFIG. 7andFIG. 8.

Furthermore, in the respective configuration examples shown inFIG. 7andFIG. 8, an aspect where the spring is used as the urging member62has been described, but the present invention is not limited to these examples. For example, a rubber or the like may be used.

As above, the embodiments of the present invention have been described, but the present invention is not limited to the above examples. Needless to say, various improvements and modifications may be performed without departing from gist according to the present invention.

REFERENCE SIGNS LIST