Patent Description:
A variety of techniques have been proposed for detecting displacement of a movable member such as a key of a musical keyboard instrument. Patent Document <NUM> discloses a configuration for detecting a displacement of a movable member by use of an excitation coil and a position detection coil disposed on a fixed member, and an excitable coil disposed on the movable member movable to the fixed member. The excitation coil, the position detection coil, and the excitable coil are each formed in a ring shape, and they are parallel to the direction of a movement of the movable member. In the above configuration, supply of a cyclic signal causes generation of a magnetic field in the excitation coil, as a result of which a magnetic field in the excitable coil due to electromagnetic induction. An induced voltage is generated in the position detection coil in accordance with the magnetic field of the excitable coil, and the generated induced voltage is a detection signal representing the position of the movable member.

The technique of Patent Document <NUM> is subjected to a drawback, however, in that in practice it is difficult to generate a magnetic field having sufficient strength for the excitable coil. Accordingly, it is not practically possible to secure a sufficient range of displacement of the movable member that makes an effective change of the level of the detection signal.

In view of the circumstances described above, an object of one aspect of the present disclosure is to secure with ease a range of displacement of a movable member that can make an effective change of the level of a detection signal.

To achieve the above-stated object, the present disclosure provides the features of the independent claims.

<FIG> is a block diagram showing a configuration of a musical keyboard instrument <NUM> according to a first embodiment of the present disclosure. The musical keyboard instrument <NUM> is an electronic musical instrument including a keyboard <NUM>, a detection system <NUM>, an information processing apparatus <NUM>, and a sound output device <NUM>. The keyboard <NUM> comprises keys <NUM> including black and white keys. The keys <NUM> are each movable members that are displaced by a playing operation of a user. The detection system <NUM> detects displacement of each of the keys <NUM>. The information processing apparatus <NUM> generates an audio signal V in accordance with a detection result made by the detection system <NUM>. The audio signal V is a signal representative of a music sound with a pitch that corresponds to one of the keys <NUM> operated by the user. The sound output device <NUM> outputs sound represented by the audio signal V. The sound output device <NUM> is a speaker or a headphone, for example.

<FIG> is a block diagram showing a specific configuration of the musical keyboard instrument <NUM>, focusing on one of the keys <NUM> of the keyboard <NUM>. Each of the keys <NUM> of the keyboard <NUM> is supported by a supporting member <NUM> by way of the supporter (balance pin) <NUM> that acts as a fulcrum. The supporting member <NUM> is a structure (frame) that supports each element of the musical keyboard instrument <NUM>. The end <NUM> of each key <NUM> is displaced vertically by pressing and releasing keys by a user. The detection system <NUM> generates a detection signal D at a level depending on a vertical position Z of the end <NUM> for each of the keys <NUM>. The position Z is expressed by an amount of displacement of the end <NUM>, relative to a rest position of the end <NUM> in a released state in which no load is applied to the key <NUM>.

The detection system <NUM> includes a detectable portion <NUM>, a signal generator <NUM> and a signal processing circuit <NUM>. The detectable portion <NUM> and the signal generator <NUM> are disposed for each key <NUM>. The signal generator <NUM> is disposed on the supporting member <NUM>. The detectable portion <NUM> is disposed on the key <NUM>. Specifically, the detectable portion <NUM> is disposed on a bottom surface of the key <NUM> (hereinafter, "mounting surface") <NUM>. The detectable portion <NUM> includes a first coil <NUM>. The signal generator <NUM> includes a second coil <NUM>. The first coil <NUM> and the second coil <NUM> oppose each other, and are vertically spaced apart from each other. A distance between the signal generator <NUM> and the detectable portion <NUM> (a distance between the first coil <NUM> and the second coil <NUM>) changes depending on the position Z of the end <NUM> of the key <NUM>.

<FIG> is a circuit diagram showing an electrical configuration of the signal generator <NUM>. The signal generator <NUM> includes a resonant circuit including an input T1, an output T2, a second coil <NUM>, a capacitive element <NUM>, and a capacitive element <NUM>. The second coil <NUM> is wired between the input T1 and the output T2. The capacitive element <NUM> is wired between the input T1 and a ground wire. The capacitive element <NUM> is wired between the output T2 and the ground wire. The signal generator <NUM> acts as a low-pass filter that reduces low-pass components of a signal supplied to the input T1.

<FIG> is a circuit diagram showing an electrical configuration of the detectable portion <NUM>. The detectable portion <NUM> includes a resonance circuit including a first coil <NUM> and a capacitive element <NUM>. Both ends of the first coil <NUM> and both ends of the capacitive element <NUM> are wired to each other. The resonant frequency of the detectable portion <NUM> is the same for the signal generator <NUM>, but it need not be.

The signal processing circuit <NUM> shown in <FIG> generates a detection signal D at a level depending on the distance between the first coil <NUM> and the second coil <NUM>.

<FIG> is a block diagram showing a specific configuration of the signal processing circuit <NUM>. The signal processing circuit <NUM> includes a supply circuit <NUM> and an output circuit <NUM>. The supply circuit <NUM> supplies a reference signal R to each of the signal generators <NUM>. The reference signal R is a current signal or a voltage signal, a level of which changes periodically. The reference signal R may be a cyclic signal of a freely selected waveform, such as a sine wave. The supply circuit <NUM> supplies the signal generators <NUM> with a reference signal R by time division. Specifically, the supply circuit <NUM> is a demultiplexer, which selects each of the signal generators <NUM> one by one, and supplies the reference signal R to the selected signal generator <NUM>. Thus, the reference signal R is supplied to each of the signal generators <NUM> by time division. It is of note that the cycle of the reference signal R is sufficiently shorter than a period during which the supply circuit <NUM> selects one signal generator <NUM>. Furthermore, the frequency of the reference signal R is substantially identical to the resonance frequencies of the detectable portion <NUM> and the signal generator <NUM>, but it need not be.

As shown in <FIG>, the reference signal R is supplied to the input T1 of the signal generator <NUM>. A current in accordance with the reference signal R is supplied to the second coil <NUM>, which generates a magnetic field in the second coil <NUM>. The electromagnetic induction generated by the magnetic field in the second coil <NUM> causes an induced current in the first coil <NUM>. As a result, a magnetic field, which has a direction such that change in the magnetic field in the second coil <NUM> is cancelled, is generated in the first coil <NUM>. Since the magnetic field in the first coil <NUM> changes depending on a distance between the first coil <NUM> and the second coil <NUM>, a detection signal d with an amplitude level δ depending on the distance therebetween is output from the output T2 of the signal generator <NUM>. The detection signal d is a cyclic signal the level of which fluctuates with the same cycle as that of the reference signal R.

The output circuit <NUM> in <FIG> generates a detection signal D by sequentially arranging on a time axis detection signals d that are sequentially output from each of the signal generators <NUM>. The detection signal D is a voltage signal with amplitude levels δ, each of which is dependent on a distance between the first coil <NUM> and the second coil <NUM> in each of the respective keys <NUM>. As described previously, the distance between the first coil <NUM> and the second coil <NUM> changes in conjunction with the position Z of each key <NUM>. Accordingly, the detection signal D is a signal depending on different positions Z of the respective keys <NUM>. The detection signal D generated by the output circuit <NUM> is supplied to the information processing apparatus <NUM>.

The information processing apparatus <NUM> in <FIG> analyzes the detection signal D supplied from the signal processing circuit <NUM>, to determine the position Z of each key <NUM>. The information processing apparatus <NUM> is realized by a computer system that includes a controller <NUM>, a storage device <NUM>, an A/D converter <NUM> and a sound source circuit <NUM>. The A/D converter <NUM> converts the detection signal D supplied from the signal processing circuit <NUM> from an analog signal to a digital signal.

The controller <NUM> comprises one or more processors for controlling each of elements of the musical keyboard instrument <NUM>. For example, the controller <NUM> is constituted of one or more types among different types, such as a Central Processing Unit (CPU), a Sound Processing Unit (SPU), a Digital Signal Processor (DSP), a Field Programmable Gate Array (FPGA), or an Application Specific Integrated Circuit (ASIC).

The storage device <NUM> comprises one or more memories that store programs executed by the controller <NUM> and data used by the controller <NUM>. The storage device <NUM> is constituted of, for example, a known recording medium, such as a magnetic recording medium or a semiconductor recording medium. The storage device <NUM> may comprise a combination of different types of recording media. The storage device <NUM> may be a portable recording medium detachable from the musical keyboard instrument <NUM>, or may be an external recording medium (e.g., online storage), with which the musical keyboard instrument <NUM> can communicate.

The controller <NUM> analyzes the position Z of each key <NUM> by analyzing the detection signal D after conversion by the A/D converter <NUM>. The controller <NUM> instructs the sound source circuit <NUM> to produce a music sound based on the position Z of each key <NUM>. The sound source circuit <NUM> generates an audio signal V representative of the music sound as instructed by the controller <NUM>. Thus, the sound source circuit <NUM> generates the audio signal V in accordance with the amplitude levels δ of the detection signal D. For example, the volume of the audio signal V is controlled in accordance with the amplitude levels δ. The audio signal V is supplied from the sound source circuit <NUM> to the sound output device <NUM>, whereby a musical sound that corresponds to playing operations performed by a user (depression or release of each key <NUM>) is output from the sound output device <NUM>. Execution of the program stored in the storage device <NUM> allows for the controller <NUM> to realize the functions of the sound source circuit <NUM>.

<FIG> is a plan view showing an example of a specific configuration of a detectable portion <NUM>. In the plan view of <FIG>, the detectable portion <NUM> is viewed from the signal generator <NUM>. <FIG> is a cross-sectional view taken along line a-a in <FIG>.

The detectable portion <NUM> according to the first embodiment comprises a wiring board <NUM> that includes a baseboard <NUM> and a wiring pattern <NUM>. The baseboard <NUM> is a rectangular member that includes surfaces F1 and F2. The surface F2 opposes the mounting surface <NUM> of a key <NUM>, and the surface F1 is opposite to the surface of the surface F2. Accordingly, the surface F1 opposes the signal generator <NUM>. The baseboard <NUM> has a width smaller than one key <NUM>.

The baseboard <NUM> has through-holes <NUM> (57a, 57b). Each through-hole <NUM> is a circular opening through the baseboard <NUM>. The wiring board <NUM> is fixed to the mounting surface <NUM> of the key <NUM> using fixing members <NUM> (71a and 71b) for respective through-holes <NUM>. Each fixing member <NUM> is a screw, and is inserted into the mounting surface <NUM>. Specifically, the fixing member 71a is inserted into the through-hole 57a, and the fixing member 71b is inserted into the through-hole 57b. Each fixing member <NUM> is a magnetic body made of magnetic material, such as iron or ferrite.

The wiring pattern <NUM> is a conductive film provided on each of the surfaces (surfaces F1 and F2) of the baseboard <NUM>. Specifically, the wiring pattern <NUM> is provided by patterning in which the conductive film that covers the entire surface of the baseboard <NUM> is selectively removed. The first coil <NUM> of the detectable portion <NUM> is composed of the wiring pattern <NUM>. Thus, for example, as compared to a configuration in which the first coil <NUM> is wound by a conductive wire, it is easier to manufacture and handle the first coil <NUM>.

The first coil <NUM> includes a first part <NUM> and a second part <NUM>. The first part <NUM> and the second part <NUM> are provided on the surface F1, and these are in different areas when viewed from the vertical direction of the surface F1. Specifically, the first part <NUM> and the second part <NUM> are adjacent to each other along the longitudinal direction of the key <NUM>.

The first part <NUM> surrounds through-hole 57a. Specifically, the first part <NUM> comprises a spiral winding that is wound clockwise from an end Ea1 of the inner circumference near the through-hole 57a to an end Ea2 at the outer circumference. The fixing member 71a overlaps the central axis of the first part <NUM>, as seen in plan view. That is, the first part <NUM> surrounds the fixing member 71a, as seen in plan view. For this reason, the fixing member 71a acts as the core of the first part <NUM>. However, the first part <NUM> does not overlap the head of the fixing member 71a inserted into the through-hole 57a, as seen in plan view.

The second part <NUM> surrounds the through-hole 57b. Specifically, the second part <NUM> comprises a spiral winding that is wound clockwise from an end Eb1 of the inner circumference near the through-hole 57b to an end Eb2 of the outer circumference. The fixing member 71b overlaps the central axis of the second part <NUM>, as seen in plan view. That is, the second part <NUM> surrounds the fixing member 71b, as seen in plan view. For this reason, the fixing member 71b acts as the core of the second part <NUM>. However, the second part <NUM> does not overlap the head of the fixing member 71b inserted into the through-hole 57b, as seen in plan view.

The wiring pattern <NUM> includes a connection wiring <NUM> provided on the surface F2 of the baseboard <NUM>. The end portions Ea1 and Eb1 are connected to each other via the connection wiring <NUM>. A capacitive element <NUM> is mounted on the surface F1, and is between the end Ea2 and the end Eb2.

As will be understood from the above description, the direction of the current flowing through the first part <NUM> opposes the direction of the current flowing through the second part <NUM>. Specifically, when a current flows through the first part <NUM> in the direction Q1, a current flows through the second part <NUM> in the opposite direction Q2 of the direction Q1. As a result, as shown in <FIG>, the first part <NUM> and the second part <NUM> are configured to generate opposite sense magnetic fields. That is, a magnetic field directed from the first part <NUM> to the second part <NUM>, and vice versa, are generated. By the above configuration, it is possible to limit or reduce expansion of the magnetic fields over to and across different keys <NUM> adjacent to each other. Accordingly, it is possible to generate a detection signal D that highly accurately represents the position Z of each of the keys <NUM>.

As explained above, in the first embodiment, the fixing members <NUM>, which are magnetic bodies, are disposed on each of the keys <NUM>. Accordingly, as compared to a configuration in which there is no magnetic body, magnetic fields generated in the first coil <NUM> are enhanced. That is, the range of displacement of a key <NUM>, at which the magnetic fields in the first coil <NUM> significantly affect those in the second coil <NUM>, is expanded. Thus, it is easy to secure the range of the displacement (detection stroke) of the key <NUM> in which the amplitude level δ of the detection signal D is effectively changed. In the first embodiment, in particular, the fixing members <NUM> for fixing the wiring board <NUM> to the key <NUM> are magnetic bodies. Accordingly, as compared to a configuration in which the wiring board <NUM> is fixed to the key <NUM> by use of other members, which differ from the magnetic bodies for enhancing magnetic fields in the first coil <NUM>, the configuration of the detection system <NUM> is simplified. Furthermore, since the fixing members <NUM> are inserted into the through-holes <NUM> of the wiring board <NUM>, the wiring board <NUM> can be fixed to the key <NUM> with a simple configuration.

In the first embodiment, the fixing member <NUM> overlaps the central axis of the first coil <NUM>. Specifically, the fixing member 71a overlaps the central axis of the first part <NUM>, and the fixing member 71b overlaps the central axis of the second part <NUM>. Accordingly, as compared to a configuration in which the fixing member <NUM> is sufficiently spaced apart from the first coil <NUM>, the magnetic fields generated in the first coil <NUM> are enhanced, and the attained effect is remarkable.

<FIG> is a plan view showing an example of a specific configuration of a signal generator <NUM>. In <FIG>, the signal generator <NUM> is viewed from the detectable portion <NUM>. <FIG> is a cross-sectional view taken along line b-b in <FIG>.

As shown in <FIG>, the signal generator <NUM> comprises a wiring board <NUM> that includes a baseboard <NUM> and a wiring pattern <NUM>. The baseboard <NUM> is a long plate member that extends over the keys <NUM>, and it includes a surface F3 and a surface F4. The surface F4 opposes a supporting member <NUM>, and the surface F3 is an opposing surface of the surface F4. Accordingly, the surface F3 opposes the detectable portion <NUM>.

The wiring pattern <NUM> is a conductive film provided on each of the surfaces (surfaces F3 and F4) of the baseboard <NUM>. Specifically, the wiring pattern <NUM> is provided by patterning in which that the conductive film that covers the entire surface of the baseboard <NUM> is selectively removed. The second coil <NUM> of the signal generator <NUM> is composed of the wiring pattern <NUM>. Thus, for example, as compared to a configuration in which the second coil <NUM> is wound by a conductive wire, it is easier to manufacture and handle the second coil <NUM>.

The second coil <NUM> includes a third part <NUM> and a fourth part <NUM>. The third part <NUM> and the fourth part <NUM> are provided on the surface F3, and these are in different areas when viewed from the vertical direction of the surface F3. Specifically, the third part <NUM> and the fourth part <NUM> are adjacent to each other along the longitudinal direction of the key <NUM>.

The third part <NUM> comprises a spiral winding that is wound counterclockwise from an end Ec1 of the inner circumference to an end Ec2 of the outer circumference. The fourth part <NUM> comprises a spiral winding that is wound counterclockwise from an end Ed1 of the inner circumference to an end Ed2 of the outer circumference. In a direction of the central axis of the second coil <NUM> (i.e., the vertical direction of the surface F3), a distance between the first coil <NUM> and the second coil <NUM> changes depending on position Z of the key <NUM>.

The wiring pattern <NUM> includes a connection wiring <NUM> provided on the surface F4 of the baseboard <NUM>. The ends Ec1 and Ed1 are connected to each other via the connection wiring <NUM>. In addition, an input T1 and an output T2 are provided on the surface F3. The capacitive element <NUM> is wired between the input T1 and the end Ec2 of the third part <NUM>. The capacitive element <NUM> is wired between the output T2 and the end Ed2 of the fourth part <NUM>. The wiring for connecting the capacitive element <NUM> and the capacitive element <NUM> to each other is wired to a ground point G that is set to the ground potential.

As will be understood from the above description, the direction of the current flowing through the third part <NUM> is opposite to the direction of the current flowing through the fourth part <NUM>. Specifically, when a current flows through the third part <NUM> in the direction Q3, a current flows through the fourth part <NUM> in the opposite direction Q4 of the direction Q3. As a result, as shown in <FIG>, the third part <NUM> and the fourth part <NUM> are configured to generate opposite sense magnetic fields. That is, a magnetic field directed from the third part <NUM> to the fourth part <NUM>, and vice versa, are generated. By the above configuration, it is possible to limit or reduce diffusion of the magnetic fields over to and across different keys <NUM> adjacent to each other. Therefore, it is possible to generate a detection signal D that highly accurately represents the position Z of each of the keys <NUM>.

In the first embodiment, in the direction of the central axis of the second coil <NUM>, the distance between the first coil <NUM> and the second coil <NUM> changes in accordance with the displacement of the key <NUM>. Thus, as compared to a configuration in which the first coil <NUM> and the second coil <NUM> are movable relatively to each other in a plane perpendicular to the central axis of the second coil <NUM>, it is possible to change the level of the detection signal D significantly in response to the displacement of the key <NUM>.

The second embodiment will be described below. It is to be noted that in each of the embodiments described below, like reference signs are used for elements having functions or effects identical to those of elements described in the first embodiment, and detailed explanations of such elements are omitted as appropriate.

<FIG> is a perspective view showing a configuration of a detectable portion <NUM> according to the second embodiment. In the first embodiment, the wiring board <NUM> included in each detectable portion <NUM> is directly fixed to the mounting surface <NUM> by the fixing members <NUM>. The detectable portion <NUM> according to the second embodiment includes a wiring board <NUM> and a support <NUM>. The support <NUM> is fixed to the mounting surface <NUM> of the key <NUM>. The wiring board <NUM> is on the support <NUM>.

<FIG> is a plan view showing an example of a state in which the wiring board <NUM> is detached from the support <NUM>. <FIG> is a plan view showing an example of a state in which the wiring board <NUM> is on the support <NUM>. <FIG> is a cross-sectional view taken along line c-c in <FIG>.

As shown in <FIG>, the support <NUM> is a flat and box-shaped structure configured to support the wiring board <NUM>. The material of the support <NUM> and manufacturing method thereof are freely selectable. For example, the support <NUM> is formed by injection molding of resin. Specifically, the support <NUM> includes a bottom <NUM>, a side wall 82a, a side wall 82b, and a rear wall <NUM>.

The bottom <NUM> is flat, and includes a holding surface Fa and a mounting surface Fb. The bottom <NUM> is rectangular, the shape of which corresponds to the outer of the wiring board <NUM>. The mounting surface Fb opposes the mounting surface <NUM>. The holding surface Fa is an opposing surface of the mounting surface Fb. The side walls 82a and 82b, and the rear wall <NUM> protrude from the holding surface Fa, and they are along the periphery of the bottom <NUM>. The side walls 82a and 82b are opposite each other, and the rear wall <NUM> extends from the side wall 82a to the side wall 82b. The wiring board <NUM> is housed in the space enclosed by the holding surface Fa of the bottom <NUM>, and three sides: the side wall 82a, the side wall 82b, and rear wall <NUM>. As shown in <FIG>, when the wiring board <NUM> is housed in the support <NUM>, the surface F2 opposes the holding surface Fa.

There are protrusions <NUM> on each of the side walls 82a and 82b. Each protrusion <NUM> protrudes from the inner surface of the side wall 82a or 82b. Each protrusion <NUM> opposes the holding surface Fa of the bottom <NUM>, and has a slight spacing from the holding surface Fa that is thicker than the thickness of the wiring board <NUM> (the baseboard <NUM>). As shown in <FIG>, the wiring board <NUM> is held between each protrusion <NUM> and the holding surface Fa.

A holding protrusion <NUM> is provided at an edge of the bottom <NUM> on the opposite of the rear wall <NUM>. The holding protrusion <NUM> protrudes from the holding surface Fa. The wiring board <NUM> is inserted through the opening between the side walls 82a and 82b. At this time, the wiring board <NUM> is slid until one end of the wiring board <NUM> reaches the inner surface of the rear wall <NUM>. When the end of the wiring board <NUM> is in contact with the inner surface of the rear wall <NUM>, the holding protrusion <NUM> opposes the other end of the wiring board <NUM>. That is, the wiring board <NUM> is held between the holding protrusion <NUM> and the rear wall <NUM>. As will be understood from the above description, the holding protrusion <NUM> is a check claw by which the wiring board <NUM> is hooked by the end of the wiring board <NUM> to hold the wiring board <NUM>. The wiring board <NUM> is attachable to and is detachable from the support <NUM>. Accordingly, the wiring board <NUM> can be replaced with ease, as compared to a configuration in which the wiring board <NUM> is directly fixed to the mounting surface <NUM>.

There are through-holes <NUM> (87a and 87b) on the bottom <NUM> of the support <NUM>. Each through-hole <NUM> is a circular opening through the bottom <NUM>. As shown in <FIG>, the support <NUM> is fixed to the mounting surface <NUM> of the key <NUM> by the fixing members <NUM> (71a and 71b) that penetrate the respective through-holes <NUM>. Each fixing member <NUM> is a screw, and it is inserted into the mounting surface <NUM>. Specifically, the fixing member 71a is inserted into the through-hole 87a, and the fixing member 71b is inserted into the through-hole 87b. As in the first embodiment, each fixing member <NUM> is a magnetic body made of magnetic material, such as iron or ferrite. When the fixing members <NUM> are inserted into the respective through-holes <NUM>, the top of the fixing member <NUM> and the holding surface Fa of the bottom <NUM> are located in the same plane.

As in the first embodiment, the first coil <NUM> is provided on the wiring board <NUM> according to the second embodiment. However, there are no through-holes <NUM> in the wiring board <NUM> according to the second embodiment. Accordingly, in the second embodiment, as compared to the first embodiment in which the through-holes <NUM> are provided on the wiring board <NUM>, it is easier to secure the region for provision of the first coil <NUM>. That is, the wiring width of the first coil <NUM> and number of turns thereof can be easily secured.

As in the first embodiment, the first coil <NUM> includes a first part <NUM> and a second part <NUM>. As shown in <FIG>, the fixing member 71a inserted into the through-hole 87a overlaps the central axis of the first part <NUM> of the first coil <NUM>, as seen in plan view. Accordingly, the fixing member 71a acts as the core of the first part <NUM>. Similarly, the fixing member 71b inserted into the through-hole 87b overlaps the central axis of the second part <NUM> of the first coil <NUM>. Accordingly, the fixing member 71b acts as the core of the second part <NUM>.

In the second embodiment, the same effects of the first embodiment are achieved. Furthermore, in the second embodiment, the fixing members <NUM>, which are used to fix the support <NUM> on the wiring board <NUM> to the key <NUM>, are magnetic bodies. Accordingly, as compared to a configuration in which the support <NUM> is fixed to the key <NUM> by use of other members, which differ from the magnetic bodies for enhancing magnetic fields in the first coil <NUM>, the configuration of the detection system <NUM> is simplified. Furthermore, since the fixing members <NUM> are inserted into the respective through-holes <NUM> of the support <NUM>, the support <NUM> can be fixed to the key <NUM> with a simple configuration.

In the first and second embodiments, an example has been described of a configuration in which the first coil <NUM> is provided on the surface F1 of the baseboard <NUM>. In the third embodiment, the first coil <NUM> is configured by stacked multiple wiring patterns <NUM>.

<FIG> are each a plan view showing a configuration of the wiring board <NUM> according to the third embodiment. In <FIG>, wirings are shown on the surface F1, and in <FIG>, wirings are shown on the surface F2. However, in the wirings on the surface F2 in <FIG>, the outline viewed from the surface F1 is shown for convenience.

The first part <NUM> of the first coil <NUM> comprises a first layer La1 and a second layer La2. The first layer La1 is provided on the surface F1, and the second layer La2 is provided on the surface F2. The first layer La1 comprises a spiral winding that is wound from an end Ea1 of the inner circumference to an end Ea2 of the outer circumference. The second layer La2 comprises a spiral winding that is wound from an end Ea3 of the inner circumference to an end Ea4 of the outer circumference. The ends Ea1 and Ea3 are mutually connected through respective conductive holes provided on the baseboard <NUM>.

The second part <NUM> of the first coil <NUM> comprises a first layer Lb1 and a second layer Lb2. The first layer Lb1 is provided on the surface F1, and the second layer Lb2 is provided on the surface F2. The first layer Lb1 comprises a spiral winding that is wound from an end Eb1 of the inner circumference to an end Eb2 of the outer circumference. The second layer Lb2 comprises a spiral winding that is wound from an end Eb3 of the inner circumference to an end Eb4 of the outer circumference. The ends Eb1 and Eb3 are connected to each other through respective conductive holes provided on the baseboard <NUM>. The end Ea2 of the first layer La1 and the end portion Eb2 of the first layer Lb1 are wired to the capacitive element <NUM>. This configuration is the same for the first embodiment.

The relay wiring <NUM> is provided on the surface F1. The relay wiring <NUM> is a straight wire, and it extends from the end E1 to the end E2. The end Ea4 of the second layer La2 of the first part <NUM> is wired to an end E1 of the relay wiring <NUM>. The end Eb4 of the second layer Lb2 of the second part <NUM> is wired to an end e2 of the relay wiring <NUM>.

According to the above configuration, currents in the same direction flow through the first layer La1 and the second layer La2 of the first part <NUM>. Currents in the same direction flow through the first layer Lb1 and the second layer Lb2 of the second part <NUM>. The direction of the current flowing through the first part <NUM> is opposites to the direction of the current flowing through the second part <NUM>.

In the third embodiment, the same effects of the first embodiment are achieved. In <FIG>, an example has been described of an aspect based on the wiring board <NUM> having the through-holes <NUM> according to the first embodiment. However, the same configuration is applied to the wiring board <NUM> having no through holes <NUM> according to the second embodiment. In the above description, the first coil <NUM> is configured by the stacked two layers, but the number of layers of the first coil <NUM> may be three or more.

<FIG> is a plan view showing an example of a configuration of a detectable portion <NUM> according to a fourth embodiment. The detectable portion <NUM> according to the fourth embodiment is composed of a wiring board <NUM>, as in the first embodiment. In the first embodiment, an example has been described of a configuration in which each of the fixing members <NUM> overlaps the corresponding central axis of the first coil <NUM>. In the fourth embodiment, the fixing members <NUM> (71a and 71b) do not overlap the corresponding central axis of the first coil <NUM>. The configuration in which the fixing members <NUM> are magnetics bodies is the same for the first embodiment.

Specifically, the through-hole 57a and the fixing member 71a are positioned closer to the first part <NUM> than the second part <NUM>. Similarly, the through-hole 57b and the fixing member 71b are positioned closer to the second part <NUM> than the first part <NUM>. That is, the first coil <NUM> is disposed between the fixing members 71a and 71b.

In the fourth embodiment, the fixing members <NUM>, which are magnetic bodies, are disposed on the key <NUM>. Accordingly, as in the first embodiment, as compared to a configuration in which there is no magnetic body, magnetic fields generated in the first coil <NUM> are enhanced. Thus, it is easy to secure the range of the displacement (detection stroke) of the key <NUM> in which the amplitude level δ of the detection signal D is effectively changed.

<FIG> is a plan view showing an example of a configuration of a detectable portion <NUM> according to a fifth embodiment. <FIG> is a cross-sectional view taken along line d-d in <FIG>. In the fifth embodiment, fixing members <NUM> (72a and 72b) are used to fix the wiring board <NUM> to the mounting surface <NUM>.

The fixing members <NUM> are staples, each of which is formed by a straight wire being bent in the same direction at two points. Specifically, each of the fixing members <NUM> includes a first staple part <NUM>, a second staple part <NUM>, and a connection part <NUM>. The first staple part <NUM> and the second staple part <NUM> are spaced apart from each other, and they are parallel. An end of the first staple part <NUM> is connected to an end of the second staple part <NUM> by the connection part <NUM>. The fixing members <NUM> are magnetic bodies made of magnetic material, such as iron or ferrite.

The baseboard <NUM> has mounting holes <NUM> (58a1, 58a2, 58b1 and 58b2). Each mounting hole <NUM> is an opening through the baseboard <NUM>. The mounting holes 58a1 and 58b1 are circular, as seen in plan view. The mounting holes 58a2 and 58b2 are semicircular notches, and are provided at an edge of the baseboard <NUM>. The mounting hole 58a1 and the mounting hole 58a2 are positioned closer to the first part <NUM> than the second part <NUM>. The mounting hole 58b1 and the mounting hole 58b2 are positioned closer to the second part <NUM> than the first part <NUM>.

The fixing members <NUM> are driven into the mounting surface <NUM> through the mounting holes <NUM> to fix the wiring board <NUM> to the mounting surface <NUM>. Specifically, the first staple part <NUM> of the fixing member 72a is driven into the mounting surface <NUM> through the mounting hole 58a1. The second staple part <NUM> of the fixing member 72a is driven into the mounting surface <NUM> through the mounting hole 58a2. Furthermore, the first staple part <NUM> of the fixing member 72b is driven into the mounting surface <NUM> through the mounting hole 58b1. The second staple part <NUM> of the fixing member 72b is driven into the mounting surface <NUM> through the mounting hole 58b2.

In the fifth embodiment, the fixing members <NUM>, which are magnetic bodies, are disposed on the key <NUM>. Accordingly, as in the first embodiment, as compared to a configuration in which there is no magnetic body, magnetic fields generated in the first coil <NUM> are enhanced. Thus, it is easy to secure the range of the displacement (detection stroke) of the key <NUM> in which the amplitude level δ of the detection signal D is effectively changed.

In the first embodiment (see <FIG>), the second embodiment (see <FIG>) and the third embodiment (see <FIG>), the fixing members <NUM> are positioned inner to the first coil <NUM>, as seen in plan view. The "inner to the first coil <NUM>" refers to an inside of the closed area surrounded by the outer circumference of the first coil <NUM>.

In contrast, in the fourth embodiment (see <FIG>) and the fifth embodiment (see <FIG>), the fixing members (<NUM> and <NUM>) are positioned outer to the first coil <NUM>, as seen in plan view. The outer to the first coil <NUM> refers to an outside of the closed area surrounded the outer circumference of the first coil <NUM>.

Specific modifications added to each of the aspects described above are described below. Two or more modes selected from the following descriptions may be combined with one another as appropriate as long as such combination does not give rise to any conflict.

<FIG> is a schematic diagram of a configuration in which the detection system <NUM> is applied to a strike mechanism <NUM> of the musical keyboard instrument <NUM>. As in an acoustic piano, the strike mechanism <NUM> is a mechanism that strikes a string (not shown) in conjunction with a displacement of each key <NUM> in the keyboard <NUM>. Specifically, the strike mechanism <NUM> includes, for each key <NUM>, a hammer <NUM> capable of striking a string by rotation and a transmission mechanism <NUM> (e.g., a whippen, jack, repetition lever, etc.) that causes the hammer <NUM> to rotate in conjunction with the displacement of the key <NUM>. By the above configuration, the detection system <NUM> detects displacement of the hammer <NUM>. Specifically, the detectable portion <NUM> is disposed on the hammer <NUM> (e.g., at a hammer shank). For example, the wiring board <NUM>, which comprises the detectable portion <NUM>, is fixed to the hammer <NUM> by the fixing members <NUM> that are magnetic bodies. In contrast, the signal generator <NUM> is disposed on the supporting member <NUM>. The supporting member <NUM> is a structure configured to support, for example, the strike mechanism <NUM>. As in the second embodiment, the wiring board <NUM> may be disposed on the hammer <NUM> via the support <NUM>. The detectable portion <NUM> may be disposed on a member of the strike mechanism <NUM> other than the hammer <NUM>.

<FIG> is a schematic diagram of a configuration in which the detection system <NUM> is applied to a pedal mechanism <NUM> of the musical keyboard instrument <NUM>. The pedal mechanism <NUM> includes a pedal <NUM> operated by a user's foot, a supporting member <NUM> that supports the pedal <NUM>, and an elastic body <NUM> that urges the pedal <NUM> in the upward vertical direction. By the above configuration, the detection system <NUM> detects the displacement of the pedal <NUM>. Specifically, the detectable portion <NUM> is disposed on the bottom of the pedal <NUM>. That is, the wiring board <NUM>, which comprises the detectable portion <NUM>, is fixed to the pedal <NUM> by the fixing members <NUM> that are magnetic bodies. The signal generator <NUM> is disposed on the supporting member <NUM> such that the signal generator <NUM> opposes the detectable portion <NUM>.

As in the second embodiment, the wiring board <NUM> may be disposed on the pedal <NUM> via support <NUM>. A musical instrument for which the pedal mechanism <NUM> is used is not limited to the musical keyboard instrument <NUM>. For example, the pedal mechanism <NUM> of the same configuration may be used in a freely selected musical instrument, such as a percussion instrument, etc..

As will be understood from the above examples, an object of detection by the detection system <NUM> is a movable member that is displaced in response to a playing operation. The movable member includes an instrument operating element, such as the keys <NUM> or the pedal <NUM>, directly operated by a user and also includes a structure such as the hammer <NUM> that is displaced in conjunction with an operation performed on an instrument playing element. However, the movable member according to the present disclosure is not limited to a member that is displaced in response to a playing operation. That is, the movable member should be understood as a displaceable member regardless of how displacement takes place.

(<NUM>) In each of the above embodiments, screws are given as an example the fixing members <NUM>, but the embodiments of the fixing members <NUM> are not limited to the above examples. For example, nails or bolts may be used as the fixing members <NUM>. Furthermore, a fixing member <NUM> (i.e., staple) shown in <FIG> may be used to fix the support <NUM>. The fixing member <NUM> shown in <FIG> includes an insertion part <NUM>, an insertion part <NUM>, and a connection part <NUM>. The insertion parts <NUM> and <NUM> are connected to each other by the connection part <NUM>. The insertion part <NUM> is inserted into the mounting surface <NUM> of the key <NUM> through a through-hole 87a. The insertion part <NUM> is inserted into the mounting surface <NUM> through a through-hole 87b. In <FIG>, the configuration in which the support <NUM> is fixed is shown. However, the wiring board <NUM> may be directly fixed to the mounting surface <NUM> using the fixing member <NUM> shown in <FIG>.

(<NUM>) In each of the above embodiments, the fixing members <NUM> for fixing the detectable portion <NUM> are used as magnetic bodies for enhancing magnetic fields in the first coil <NUM>. However, there may be disposed magnetic bodies that differ from the fixing members <NUM>. That is, the magnetic bodies for enhancing magnetic fields in the first coil <NUM> may not have a function of fixing the detectable portion <NUM>.

(<NUM>) In each of the above embodiments, there is shown a configuration in which the musical keyboard instrument <NUM> includes the sound source circuit <NUM>. However, the sound source circuit <NUM> may be omitted in a configuration in which the musical keyboard instrument <NUM> has a sound producing mechanism such as strike mechanism <NUM>, for example. The detection system <NUM> is used to record how the musical keyboard instrument <NUM> is played. The sound producing mechanism and the sound source circuit <NUM> are a sound generator that generates sound in accordance with the results of the detection by the detection system <NUM>.

As will be understood from the above description, the present disclosure may be considered to be an apparatus (instrument playing apparatus) that controls a music sound by outputting to the sound source circuit <NUM> or the sound producing mechanism an operation signal in accordance with a playing operation. The concept of the instrument playing apparatus includes not only an instrument (the musical keyboard instrument <NUM>) provided with the sound source circuit <NUM> or the sound producing mechanism as described in each of the above embodiments, but also a device not provided with the sound source circuit <NUM> or a sound producing mechanism (e.g., a MIDI controller or the pedal mechanism <NUM> as described above). That is, the instrument playing apparatus according to the present disclosure is explained as an apparatus operated by an instrument player (or an operator) for playing an instrument.

(<NUM>) In each of the above embodiments, an example has been described of a configuration in which the first coil <NUM> includes a first part <NUM> and a second part <NUM>. However, the first coil <NUM> may not be configured by two coils. For example, as shown in <FIG>, the first coil <NUM> may be configured by a single coil (e.g., either the first part <NUM> or the second part <NUM>). In the configuration shown in <FIG>, the first coil <NUM> is configured such that a fixing member <NUM> inserted into a through-hole <NUM> is surrounded by the first coil <NUM>, as seen in plan view. As shown in <FIG>, one first coil <NUM> may be disposed along the longitudinal direction of the key <NUM> such that fixing members <NUM> for fixing the wiring board <NUM> are surrounded by the first coil <NUM>, as seen in plan view.

Furthermore, as shown in <FIG>, a fixing member <NUM> according to the fifth embodiment may be disposed inner to the first coil <NUM>, as seen in plan view. The configuration in which the first coil <NUM> is a single coil may be applied to the second to fourth embodiments. Similarly, the second coil <NUM> may not be configured by two coils (the third part <NUM> and the fourth part <NUM>).

(<NUM>) In each of the above embodiments, an example has been described of a configuration in which a distance between the first coil <NUM> and the second coil <NUM> changes by a playing operation. Instead of this configuration, an area at which the first coil <NUM> opposes the second coil <NUM> (hereinafter, "opposing area") may change by a playing operation. The amplitude level δ of the detection signal d output from the signal generator <NUM> changes in response to the opposing area. As shown in the above examples, in the present disclosure, the opposing area or the distance between the first coil <NUM> and the second coil <NUM> changes by a playing operation.

(<NUM>) In each of the above embodiments, magnetic bodies (fixing members <NUM>), each of which is an example of a movable member, are disposed on the key <NUM>. However, the magnetic bodies may be disposed on the signal generator <NUM>. For example, fixing members <NUM> for fixing the signal generator <NUM> (in particular, the baseboard <NUM>), such as screws, are used as magnetic bodies. According to the configuration in which the magnetic bodies are disposed on the signal generator <NUM>, magnetic fields generated in the second coil <NUM> are enhanced. Thus, it is easy to secure the range of displacement (detection stroke) of the key <NUM> in which the level of the detection signal D is effectively changed. Such an effect is the same as that of the foregoing embodiments. The foregoing configuration in which the magnetic bodies are disposed on the key <NUM> can apply to the magnetic bodies disposed on the signal generator <NUM>.

In addition to the configuration in which the magnetic bodies are displaced on the key <NUM>, additional magnetic bodies may be disposed on the signal generator <NUM>. Alternatively, in addition to the magnetic bodies disposed in the key <NUM>, additional magnetic bodies is disposed on the signal generator <NUM>. That is, the magnetic bodies, such as the fixing members, may be disposed on at least one of the key <NUM> (movable member) or the signal generator <NUM>.

The following configurations are derivable from the embodiments described above.

A detection system according to one aspect (Aspect <NUM>) of the present disclosure is a detection system for detecting a displacement of a movable member in accordance with a playing operation, the detection system including: a detectable portion that is disposed on the movable member and includes a first coil; a signal generator configured to: include a second coil that generates a magnetic field by receiving a supply of a current, and generate a detection signal with a level depending on a distance between the detectable portion and the second coil; and a magnetic body that is disposed on at least one of the movable member or the signal generator.

By this configuration, an electromagnetic induction generated by the magnetic field in the second coil causes a current in the first coil. As a result, a magnetic field, which has a direction such that change in the magnetic field in the second coil is cancelled, is generated in the first coil. Accordingly, a detection signal with a level depending on the distance between the detectable portion and the second coil is generated by the signal generator. That is, a detection signal is generated in accordance with a displacement of the movable member.

The magnetic body is disposed on at least one of the movable member or the signal generator. Accordingly, as compared to a configuration in which there is no magnetic body, a magnetic field generated in the first coil or the second coil is enhanced. Thus, it is easy to secure the range of the displacement (detection stroke) of the movable member in which the amplitude level of the detection signal is effectively changed.

Claim 1:
A detection system (<NUM>) for detecting a displacement of a movable member (<NUM>) in accordance with a playing operation, the detection system (<NUM>) comprising:
a detectable portion (<NUM>) that is disposed on the movable member (<NUM>) and includes a first coil (<NUM>);
a signal generator (<NUM>) configured to:
include a second coil (<NUM>) that generates a magnetic field by receiving a supply of a current, and
generate a detection signal with a level depending on a distance between the detectable portion (<NUM>) and the second coil (<NUM>); and
a magnetic body that is disposed on at least one of the movable member (<NUM>) or the signal generator (<NUM>);
characterized in that
the detectable portion (<NUM>) includes a wiring board on which the first coil (<NUM>) is provided, and
the magnetic body includes a fixing member for fixing the wiring board to the movable member (<NUM>).