JP6256521B2 - Electronic keyboard instrument - Google Patents

Description

  The present invention relates to an electronic keyboard instrument, and more particularly, to an electronic keyboard instrument and an acoustic adjustment system having an acoustic structure with less acoustic characteristics generated from the instrument.

  In Patent Document 1 below, in an electronic keyboard instrument having a housing in which a speaker is accommodated, only sound is emitted from the sound emitting surface of the speaker so that the sound emitted from the speaker can be easily heard by the performer. There is also disclosed an electronic keyboard instrument having a sound emission hole such as a tone escape that emits sound from a speaker toward the performer from the internal space of the housing.

JP-A-2005-202190

In the space behind the speaker of the casing in which the speaker such as an electric keyboard instrument is built, a natural vibration state having a resonance frequency corresponding to the shape of the casing or the like is generated by the vibration of the speaker.
The present invention provides an electronic keyboard instrument that can reduce unnecessary resonance generated in a space behind a speaker in a housing in an electronic musical instrument having a built-in speaker.

In order to achieve the above-described object, an electronic keyboard instrument according to the present invention includes a casing, a keyboard that is supported in a state exposed from the casing, and a musical tone generator that generates a musical tone signal according to the operation of the keyboard. An electronic keyboard instrument comprising: a circuit; and a speaker that emits a musical sound signal generated by the musical sound generation circuit, wherein the musical sound generation circuit and the speaker are housed in an internal space of the housing. A first sound emission path for guiding the sound emitted from the sound emitting surface of the speaker to the outside and propagating it outside the housing; and the sound emitted from behind the sound emitting surface of the speaker via the internal space A second sound emission path for propagating from the gap of the keyboard to the outside of the housing is formed, and the internal space in which the second sound emission path is formed has the internal space by driving the speaker. Specific frequency generated in Specific control points antinode of the sound pressure of the vibration mode is located, the resonator to reduce the sound pressure at the location of the antinode of the sound pressure of the natural vibration mode by resonance at the specific frequency is provided, the resonance of Is provided with an adjusting mechanism for adjusting the frequency at which it resonates.

  According to the present invention, in an electronic keyboard instrument with a built-in speaker, unnecessary resonance that occurs in the space behind the speaker in the housing can be reduced.

1 is a perspective view illustrating an appearance of an electronic keyboard instrument according to Embodiment 1. FIG. 1 is a perspective view of an electronic keyboard instrument according to Embodiment 1. FIG. It is the figure which looked at the electronic keyboard musical instrument shown in FIG. 2 from the upper surface. 1 is a diagram illustrating a resonator according to a first embodiment. (A)-(c) is an image figure showing the reverberation of the propagation sound of a 1st sound emission path | route and a 2nd sound emission path | route. (A) And (b) is an image figure showing the reverberation of the propagation sound of a 1st sound emission path | route and a 2nd sound emission path | route. (A) And (b) is a figure explaining the wavelength of the natural vibration mode of the housing | casing part which concerns on Embodiment 1. FIG. (A)-(c) is a figure which shows the frequency characteristic when not providing with the resonator in Embodiment 1. FIG. 6 is a perspective view of an electronic keyboard instrument according to Embodiment 2. FIG. FIG. 10 is a front view of the electronic keyboard instrument shown in FIG. 9. It is a figure of the state which removed the upper front board of the electronic keyboard musical instrument shown in FIG. It is sectional drawing of the electronic keyboard instrument at the time of cut | disconnecting by the cutting line BB in FIG. It is a figure of the state which removed the speaker on the lower front board of the electronic keyboard musical instrument shown in FIG. It is sectional drawing of an electronic keyboard instrument when cut | disconnecting by the cutting line AA in FIG. (A) And (b) is a figure explaining the position of the partition plate which concerns on Embodiment 2. FIG. It is a figure which shows the listening sound pressure frequency characteristic in the player position at the time of providing a partition plate in Embodiment 2. FIG. (A)-(d) is a figure showing the resonator based on Embodiment 2. FIG. FIG. 10 is a diagram illustrating the position of the opening of the second resonator according to the second embodiment. It is a figure which shows the listening sound pressure frequency characteristic for every installation pattern of the resonator about R part in FIG. It is a figure which shows the installation pattern of a resonance body. 6 is a perspective view of an electronic keyboard instrument according to Embodiment 3. FIG. FIG. 21 is a front view of the electronic keyboard instrument shown in FIG. 20. It is sectional drawing of the electronic keyboard instrument at the time of cut | disconnecting by the cutting line XXII-XXII in FIG. It is a figure which shows the position of the speaker in a speaker box, and the arrangement | positioning position of a resonance body. It is a figure which shows the mode of the sound pressure in case the resonator is not arrange | positioned in a speaker box. It is a figure which shows the mode of the sound pressure at the time of arrange | positioning a resonator in a speaker box. It is a figure which shows the mode of the sound pressure at the time of arrange | positioning a resonator in a speaker box. It is a figure which shows the mode of the sound pressure in case the resonator is not arrange | positioned in a speaker box. It is a figure which shows the mode of the sound pressure at the time of arrange | positioning a resonator in a speaker box. It is a figure which shows the mode of the sound pressure at the time of arrange | positioning a resonator in a speaker box. (A) And (b) is the simplified view which looked at the internal space of the housing | casing part which concerns on the modification 1 from the upper surface. (A)-(d) is the simplified view which looked at the internal space of the housing | casing part which concerns on the modification 2 from the front. (A)-(c) is a figure explaining the shape of the housing | casing part of the electronic keyboard musical instrument which concerns on the modification 3. FIG. (A) is the figure which represented typically the external appearance of the plate vibration resonance body which concerns on the modification 4. FIG. (B) is sectional drawing which looked at the plate vibration resonator from arrow VI-VI in (a). (A) is the figure which represented typically the external appearance of the Helmholtz resonator which concerns on the modification 4. FIG. (B) is sectional drawing which looked at the Helmholtz resonator from arrow VIII-VIII in (a). (A) is the figure which represented typically the external appearance of the resonator which concerns on the modification 4. FIG. (B) is sectional drawing which looked at the resonator from arrow II-II in (a). (A)-(d2) is a figure showing the tubular resonance body which has the adjustment mechanism which concerns on the modification 5. FIG. (A) And (b) is a figure showing the Helmholtz resonator which has the adjustment mechanism which concerns on the modification 5. FIG. (A) is a figure which shows the example of installation of the partition and the resonance body which concerns on the modification 6. FIG. (B) is a diagram schematically showing the appearance of the partition / resonator. It is a figure showing the electronic keyboard instrument which concerns on the modification 7. FIG. (A)-(c) is a figure which shows the example of installation of the speaker and resonance body in the internal space of the housing | casing part which concerns on Embodiment 2. FIG.

<Embodiment 1>
FIG. 1 is a perspective view showing an appearance of an electronic keyboard instrument according to the present embodiment. As shown in FIG. 1, the electronic keyboard instrument 1 includes a keyboard unit 2, a casing 3 that supports the keyboard unit 2, and a pedal unit 4 that is provided near the lower center of the casing 3.
The keyboard unit 2 is provided on the front side (performer side) of the drawing, and has a plate-shaped mouth bar portion 14 extending in the horizontal direction, and plate-like arm portions 13, 13 extending from the both ends of the mouth bar portion 14 to the back side. And a shelf plate 19 (see FIG. 3) provided so as to cover the bottom of the U-shaped frame formed by the mouth bar portion 14 and the arm portions 13 and 13. In a frame constituted by the arm portions 13 and 13, the mouth bar portion 14 and the shelf board 19, a keyboard 11 in which white keys and black keys are arranged is accommodated and arranged so as to cover an upper part on the back side of the keyboard 11. An operation panel 12 including a power switch and various operation switches is provided. Above the keyboard 11 is provided a front plate 11a (front side surface) which is a side surface of the casing 3 in front of the electronic keyboard instrument 1 (performer side). 17a (sound emission hole) is formed. In addition, a keyboard cover 15 is provided to cover the keyboard 11, and the keyboard cover 15 is configured to be pulled out to the performer side by the slide mechanism 151, and covers the keyboard 11 when pulled out to the performer side to the end. It has become. In the state shown in FIG. 1, the keyboard lid 15 is pulled back to the back side (opposite to the performer), so that the performance portion of the keyboard 11 is exposed. Each key of the keyboard 11 is provided with a detection switch (not shown) for detecting a key pressed by the performer. The detection switch outputs an operation signal corresponding to the detected key to a musical tone signal detection circuit described later.

The casing 3 has side plates 18 and 18 extending in the vertical direction for supporting the left and right ends of the keyboard unit 2. The lower ends of the side plates 18 and 18 are connected by a bottom member 21, and the upper ends of the side plates 18 and 18 are connected by a plate-like roof plate 17. The roof plate 17 covers the upper part of the electronic keyboard instrument 1 so as to follow the upper shape of the side plates 18 and 18. The rear sides of these side plates 18, 18, roof plate 17 and shelf plate 19 are covered with a back plate portion (not shown). The tread bases 22 and 22 are provided so as to protrude from the vicinity of the bottoms of the side plates 18 and 18 to the performer side, and the case base 3 is stably placed by the tread base 22. A music score plate 16 is provided on the upper surface of the center of the roof plate 17, and a plurality of tone escapes 17 a (broken line frames) provided in the width direction are formed near the upper portion of the keyboard cover 15. Hereinafter, 17a is referred to as an acoustic escape portion or TE. The acoustic escape portion 17a includes an escape hole and a saran net covering the outer surface. The TE may be composed of only the acoustic escape hole (no saran net).
In the above-described configuration, a space partitioned by the mouth bar portion 14, the shelf board 19, the arm board portion 13, the side plate 18, the roof plate 17, the back plate portion, the keyboard 11, and the operation panel 12 is configured. This space has a property close to that of a closed space, but allows air to enter and exit through the TE 17a or the gap between the keys of the keyboard 11 and the like.
The pedal unit 4 is housed in the center of the bottom member 21 with the pedal protruding toward the performer.

  Next, the detail of the housing | casing part 3 is demonstrated. FIG. 2 shows a perspective view of the electronic keyboard instrument 1 shown in FIG. 1 with the keyboard lid 15 covering the keyboard 11 and the roof plate 17 removed, and FIG. 3 shows the electronic keyboard instrument 1 shown in FIG. It is the figure seen from the upper surface. As shown in FIGS. 2 and 3, two speakers 30 (30 a and 30 b) that emit a musical sound signal are provided in the internal space of the housing unit 3. The speaker 30 is attached so that the sound emitting surface faces downward, and a sound emitting hole is provided in the shelf 19 at a position corresponding to the sound emitting surface. The sound emitted from the speaker 30 is propagated to the performer through this sound emission hole. This propagation path is hereinafter referred to as a first sound emission path (broken line arrow W1 in FIG. 1). Further, in a state where the operation part of the keyboard 11 is exposed, sound emitted from behind the sound emitting surface of the speaker 30 passes through the internal space of the housing unit 3 and the TE 17a provided on the roof plate 17 and the keyboard. 11 propagates to the performer through the gap between the keys. This propagation path is hereinafter referred to as a second sound emission path (broken arrow W2 in FIG. 1).

  In the internal space of the housing section 3, a musical sound signal for generating a musical sound signal based on four resonators (resonators) 32 (32 a, 32 b) configured in a rectangular parallelepiped tube shape and an operation signal indicating a pressed key A circuit board 34 such as a generation circuit is provided. Further, at least one circuit component is provided in the internal space of the housing unit 3. Here, the resonator 32 according to the present embodiment will be described with reference to FIG. FIG. 4 is a diagram illustrating a resonator 32 that is an example of the resonator according to the present embodiment. The left figure of FIG. 4 is a diagram schematically showing the appearance of the resonator 32. For example, the resonator 32 is formed of a formed body made of cardboard or pulp mold, or a material such as metal or synthetic resin is tubular. It is a resonance tube formed. The resonator 32 includes an opening (open portion) 321 (control point) in which one end portion in the longitudinal direction is opened, a hollow region 322 leading to the opening 321, and a closed portion 323 in which the other end is closed. And have. The resonator 32 is an example of a tubular body in which a part of the resonator 32 includes an open end (opening 321) as an open part and the other end includes a closed end (closed part 323). The length of the hollow region 322 of each resonator 32 is the same length L. As shown in FIG. 4, the diameter of the resonator 32 is smaller than the distance between the opening 321 (open end) and the closing part 321 (closed end). The vicinity of the opening 321 of the resonator 32 has air permeability such as glass wool, cloth, sponge, gauze, etc., and may be blocked by a flow resistance material having flow resistance, or foamed urethane rubber. It may be blocked with a flow resistance material having a structure with a vent hole made of a material such as. Moreover, you may shape | mold only an opening part narrowly with these flow resistance materials.

  Returning to FIG. 2 and FIG. 3, the description will be continued. In the internal space of the housing unit 3, the resonator 32 is fixed to the resonator 32 so that the longitudinal surface of the resonator 32 is in contact with the surface of the back plate 20 and is positioned outside the position where the speaker 30 is provided. And is fixed by an adhesive or the like. The two resonators 32a are arranged such that each opening 321 faces the arrow L direction and the R direction, that is, the outside of the casing, and the two resonators 32b have each opening 321 indicated by an arrow L. Direction and R direction, that is, facing each other and facing the inside of the housing. That is, the resonators 32 a and 32 b are arranged so that the axes thereof are parallel to the arrangement direction in which a plurality of keys are arranged in the internal space of the housing unit 3.

  By the way, the TE 17a is provided to enhance the sound image of the musical sound according to the operation of the keyboard 11. As shown in FIG. 5 (a), the second sound emission path (dashed line in FIG. 1) is derived from the reverberation A of the original sound of each instrument propagating from the first sound emission path (dashed arrow W1 in FIG. 1). It is desirable that the size and length of the reverberation B of the sound for each keyboard propagated from the arrow W2) is reduced. For example, as shown in FIGS. 5B and 5C, when the reverberation B is larger or longer than the reverberation A, the reverberation A is drowned out, and the sound grain and the keyboard are different. It becomes a factor which breaks the balance of the sound volume. Note that when the digital equalizer is used to adjust the frequency characteristics of the musical sound signal input to the speaker 30 before amplification, the reverberation A and reverberation B before adjustment are reverberation A ′ and reverberation, as shown in FIG. Although it is adjusted to B ′, the inclination of the reverberation B does not change just by reducing the sound pressure levels of the reverberation A and the reverberation B as a whole.

  In the present embodiment, by providing the resonator 32 described above, the inclination of the reverberation B is adjusted so as to be smaller and shorter than the reverberation A without changing the inclination of the reverberation A, as shown in FIG. . Specifically, among the natural vibration modes of the resonance frequency in the internal space of the housing unit 3, the reverberation of the sound having the resonance frequency excited by the driving of the speaker 30 is in the state shown in FIG. In addition, a resonator 32 is provided at a position that is an antinode of the sound pressure of the natural vibration state of the resonance frequency.

  Here, the operation of reducing the sound pressure by the resonator 32 will be described. When sound waves from the internal space of the housing 3 enter the opening 321 of the resonator 32 shown in the left diagram of FIG. 4, the sound waves enter the hollow region 322 from the opening 321 and are reflected by the closed portion 323. Then, the sound wave having a wavelength corresponding to four times the length L of the hollow region 322 creates a natural vibration state SW, as shown in the right diagram of FIG. As the vibration is repeated, friction on the inner wall surface of the resonator 32, viscous action between gas molecules at the opening 321 and sound waves having a half wavelength (= half cycle) are emitted from the resonator. Acoustic energy is consumed by one or both of the phase interference action and the two actions that are continuously performed, and the sound pressure is reduced in the vicinity of the opening 321 around this wavelength. The resonator 32 is arranged so that the hollow region 322 is connected to a space to which sound is attenuated, so that sound in the space enters the opening 321 of the resonator 32 and the resonator 32 resonates. Reduce the sound pressure in the vicinity.

  The inventors have, for example, 280 to 340 Hz when the width of the casing 3 in the key arrangement direction (hereinafter referred to as the lateral width of the casing 3) is about 1300 mm (most often in the case of 88 keys). It has been experimentally obtained that the frequency (corresponding to the keyboard sound of C3 to F3) is excited. Therefore, in order to reduce the sound pressure of 280 to 340 Hz excited in the internal space of the casing unit 3, the length of the hollow region 322 of the resonator 32 is ¼ of the wavelength of the sound wave in the frequency band. Should be set.

Here, the natural vibration state generated in the internal space of the housing unit 3 will be described. The natural frequency fN in the sealed hollow rectangular parallelepiped is the natural frequency fN when the length in the x-axis direction is Lx, the length in the y-axis direction is Ly, and the length in the z-axis direction is Lz. Satisfies the relationship of the following formula (1). In equation (1), c0 represents the speed of sound, and nx, ny, and nz are values representing the orders of the natural vibration modes, and are arbitrary integers greater than or equal to “0”.

  In the internal space of the rectangular parallelepiped, a natural frequency exists for any combination of the values of the orders nx, ny, and nz. According to the equation (1), the natural frequency obtained when two of nx, ny, and nz are “0” is the natural frequency of the one-dimensional mode. This natural frequency corresponds to the frequency of the natural vibration state parallel to one axis in the internal space. The natural frequency in which one of nx, ny, and nz is “0” is the natural frequency of the two-dimensional mode. This natural frequency is parallel to a pair of parallel wall surfaces in the internal space and corresponds to a frequency of a natural vibration state incident obliquely on the other two pairs of wall surfaces. The natural frequency where none of nx, ny and nz is “0” is the natural frequency of the three-dimensional mode. This natural frequency corresponds to the frequency of the natural vibration state incident obliquely on all the wall surfaces in the internal space of the rectangular parallelepiped.

  The second-order (nx = 2) natural frequency in the one-dimensional mode when the casing 3 is sealed, that is, when the TE 17a or the like is not provided is 250 Hz from the above equation (1). This is a frequency having a wavelength corresponding to the lateral width of the casing 3. The 280 to 340 Hz obtained by the experiment is 15 to 30% higher than this frequency and has a shorter wavelength than the sealed state. The inventors considered that this was due to the influence of the sound emission path such as the TE 17a and the key gap of the keyboard 11 on the casing 3. For example, in the case of the acoustic tube M having the opening v1 and the hollow region v2 as shown in FIG. 7A, when the opening v1 is extremely small with respect to the hollow region v2, it is the same as the double closed tube. (B) As shown in (i), the wavelength of the primary natural vibration state in the acoustic tube M is ½ wavelength. Further, when the opening v1 of the acoustic tube M is extremely large with respect to the hollow region v2, it is the same as the single-open tube, and as shown in FIGS. The wavelength of the vibration mode is 3/4 wavelength, and the wavelength is shorter than those in FIGS. 7B and 7I. The same applies to the secondary case. In the case of the casing 3 provided with the TE 17a and the like, as can be seen from the experimental results, FIG. 7 (b) (b) (i) and FIG. It becomes the wavelength shown in ii). That is, it is considered that the wavelength is shorter than that in the case of both closed tubes and the wavelength is longer than that in the case of a single open tube.

  In the internal space of the housing 3, the two speakers 30 are driven in the same phase, so that the natural frequencies of the second and fourth natural vibration modes in which the nodes of the sound pressure in the internal space are even numbers are particularly easily excited, The natural frequency of the first-order natural vibration mode with one sound pressure node is difficult to be excited. Therefore, the resonator 32 may be designed to have a length that is ¼ of the wavelength of the specific frequency that is 15 to 30% higher than the frequency of the wavelength corresponding to the width of the casing 3. Further, in the internal space of the housing unit 3, the resonator 32 is arranged such that the opening 321 (control point) of the resonator 32 is located at least one of the antinodes of the sound pressure of the specific vibration state of the specific frequency. By doing so, the sound pressure of the specific frequency (280 to 340 Hz in this example) of the sound generated in the internal space when the sound due to the sound emitted from the speaker 30 is generated is reduced.

  FIG. 8A is a diagram showing the frequency characteristics in the internal space when the resonator 32 designed as described above is provided in the internal space of the casing 3 and when it is not provided. FIG. 8B shows the frequency characteristics at the player position when the resonator 32 is provided in the internal space of the casing 3 and when it is not provided. The solid lines in FIGS. 8A and 8B show the frequency characteristics when the resonator 32 is not provided in the internal space, and it can be seen that excitation is performed at a frequency of 280 to 340 Hz. The broken lines in FIGS. 8A and 8B show frequency characteristics when the resonator 32 is provided in the internal space, and the sound pressure of 280 to 340 Hz is reduced by providing the resonator 32. FIG. 8C is a diagram showing a change in sound pressure of a sound of 280 to 340 Hz when the resonator 32 is provided in the internal space of the casing 3 and when it is not provided. In FIG. 8C, the solid line indicates the frequency characteristic when the resonator 32 is not provided in the internal space, and the broken line indicates the frequency characteristic when the resonator 32 is provided in the internal space. According to this figure, by providing the resonator 32, unnecessary resonance is suppressed. As a result, the peak position shifts forward, so that the sound rises faster and the sound can be heard clearly.

In the above-described embodiment, the resonator 32 is located outside the position where the speaker 30 is provided in the internal space of the casing 3 and is located at the antinode of the sound pressure of the specific vibration state of the specific frequency. An example in which four resonators 32 are provided so that the opening 321 is located is shown in FIGS. In this example, a natural vibration state having a wavelength substantially equal to the length of the casing 3 in the key arrangement direction is generated, and the positive belly of the sound pressure of the natural vibration state of the frequency to be controlled to reduce the sound pressure is the case. Since the antinodes of sound pressure are located near the center at both ends of the body part 3, the openings (control points) 321 of the four resonators 32 are provided at positions corresponding to the antinodes. It was configured as follows. Thus, by providing the openings 321 of the resonator 32 at all antinode positions of the sound pressure of the natural vibration mode of the frequency to be controlled, the sound pressure of the frequency may be reduced. You may make it provide the opening part 321 of the resonator 32 in the place of the antinode of sound pressure. That is, of the four resonators 32 shown in FIG. 2, the two resonators 32b closer to the center may be removed, or only the resonators 32a at both ends excluding the two resonators 32b closer to the center. May be. Further, only one of the resonators 32b near the center shown in FIG. 2 may be arranged. That is, it is only necessary that the opening 321 of the resonator 32 that resonates at the frequency is located at least one of the antinodes of the sound pressure of the natural vibration state of the frequency to be controlled. Even in such a case, there is an effect of reducing the sound pressure as compared with the case where the resonator 32 is not provided.
As can be seen from the above, if the acoustic characteristics vary due to various conditions of the chassis (shape and arrangement of obstacles (electronic parts such as power supplies) in the chassis) or if you want to raise or lower the frequency characteristics that you want to emphasize In addition, by disposing a resonator having a position and a length corresponding to the frequency, it is possible to manufacture a casing having acoustic characteristics that meet some intention of the designer.

<Embodiment 2>
FIG. 9 shows a perspective view of the electronic keyboard instrument according to the present embodiment. The electronic keyboard instrument 1A includes a keyboard unit 2A and a housing portion 3A that supports the keyboard unit 2A.
The keyboard unit 2A includes a plate-shaped mouth bar portion 44 extending in the horizontal direction, plate-shaped side plates 48 and 48 extending from the both ends of the mouth bar portion 44 to the back side, and the mouth bar portion 44 and the side plates 48 and 48, respectively. It has the shelf board 53 (refer FIG. 12) provided so that the bottom part of a U-shaped frame may be covered. A keyboard 41 in which white keys and black keys are arranged is arranged on a frame formed by the side plates 48, 48, the mouth bar portion 44 and the shelf plate 53. Further, the back of the keyboard 41 is covered, and a keyboard lid 45 is rotatably provided. Further, the timepiece section 42 is provided with a power switch and various operation switches. When the keyboard cover 45 is opened so that the keyboard 41 can be seen, the surface of the keyboard cover 45 that is visible to the performer has a musical score receiver 46 and a front cover 451. The keyboard cover 45 is arranged on the player's side. In a state where the keyboard 41 is rotated, the keyboard 41 is covered. In a state shown in FIG. 9, the performance portion of the keyboard 41 is exposed. Each key of the keyboard 41 is provided with a detection switch (not shown) for detecting a key pressed by the performer. The detection switch outputs an operation signal corresponding to the detected key to a musical tone signal detection circuit described later.

The housing 3A has arm portions 43, 43 extending in the vertical direction for supporting the left and right ends of the keyboard unit 2A. The lower ends of the side plates 48, 48 behind the arm portion 43 are connected by a plate-like bottom plate 54 (see FIG. 12), and the upper ends of the side plates 48, 48 are connected by a plate-like roof plate 47. Has been. The back sides of these side plates 48 and 48 and the roof plate 47 are covered with a back plate (not shown). The front plate 49 is attached so as to cover from the upper end portion of the roof plate 47 to the rear portion of the keyboard, and a TE 49a (broken line frame) is provided on the upper portion of the front plate 49. A lower front plate upper 52a and a lower front plate lower 52b are attached so as to cover from the bottom surface of the shelf plate 53 to the lower end portion of the bottom plate 54. The lower front plate upper 52a is provided with sound emitting holes and saran nets 51a and 51b for emitting musical sounds from the speakers 60 at positions corresponding to the speakers 60 (see FIG. 12). Further, the front leg portions 50, 50 are provided so as to protrude from the vicinity of the bottom of the arm portions 43, 43 to the performer side, and the housing portion 3A is stably standing by the front leg portion. . The pedal unit 4A is housed in the center of the lower front plate lower 52b with each pedal protruding toward the performer.
In the above-described configuration, a space partitioned by the roof plate 47, the side plate 48, the upper front plate 49, the rear plate 55, the keyboard 41, the lower front plate upper 52a, the lower front plate lower 52b, and the bottom plate 54 is configured. This space has a property almost similar to a closed space as in the first embodiment, but allows air to enter and exit from the gap between the keys of the TE 49a and the keyboard 41.

  Here, the internal structure of the housing 3A will be described. FIG. 10 is a front view of the electronic keyboard instrument 1A shown in FIG. 9, and FIG. 11 is a view of the electronic keyboard instrument 1A shown in FIG. 12 is a cross-sectional view of the electronic keyboard instrument 1A when cut along the cutting line BB in FIG.

  As shown in FIG. 12, the shelf plate 53 is supported by the front leg portion 50, the lower front plate upper 52 a, the lower front plate lower 52 b, and the side plate 48. An acoustic passage space P is provided between the shelf plate 53 and the back plate 55. The internal space of the housing 3A includes an acoustic passage space above the shelf 53 (hereinafter referred to as the upper internal space S1) and an acoustic passage space in which the speakers 60a and 60b are provided (hereinafter referred to as the lower internal space S2). Is configured to be connected via an acoustic path space P between the shelf board 53 and the back board part 55. That is, the casing 3A has, as its internal space, a lower internal space S2 (first chamber) and an upper internal space S1 (second chamber) partially partitioned by a shelf 53 on which the keyboard 41 is placed. Is defined. As shown in FIG. 12, the acoustic passage space P has a narrower width in the depth direction than the upper internal space S1 and the lower internal space S2. The internal space of the housing 3A is more complicated than a simple rectangular structure like the structure of the housing 3 shown in the first embodiment. Also, as shown in FIG. 12, baffle plates 61 (61a, 61b) to which speakers 60 (60a, 60b) are attached are provided at positions on the lower front plate 52a of the housing 3A. A partition plate that partitions the bottom surface of the shelf plate 53 to the bottom plate 54 so that the speakers 60a and 60b are spatially independently provided in the key arrangement direction below the shelf plate 53 in the internal space of the housing 3A. 70 (70a, 70b) is provided (see FIGS. 11 and 12). The speaker 60 is attached such that the sound emitting surface faces the player side, and a sound emitting hole 62 is provided on the lower front plate 52a at a position corresponding to the sound emitting surface. The sound emitted from the speaker 60 is propagated to the performer through the hole 62 (first sound emission path W1). Further, a sound emitted from behind the sound emitting surface of the speaker 60 propagates to the upper internal space S1 via the acoustic path space P narrowed from the lower internal space S2, and TE49a provided on the front plate 49 and The sound is transmitted to the performer through the gap between the keys on the keyboard 41 (second sound emission path W2).

  FIG. 13 shows a state where the upper front plate lower 52a and the lower front plate lower 52b of the electronic keyboard instrument 1A and the baffle plate 61 to which the speaker 60 is attached are removed. As shown in this figure, in the space between the partition plate 70a and the partition plate 70b, a circuit board 90 such as a musical tone signal generation circuit and a tone generator circuit and the pedal unit 4A are installed. Of the spaces partitioned by the partition plates 70a and 70b provided in the lower internal space S2, the spaces where the speakers 60a and 60b are respectively provided (hereinafter referred to as speaker installation spaces) Each of the resonators 80 including the first resonator 80a and the second resonator 80b is installed. Here, FIG. 14 shows a cross-sectional view of the electronic keyboard instrument 1A when cut along the cutting line AA in FIG. As shown in this figure, each resonator 80 is provided at a position on the outer side in the lower internal space S <b> 2 from the position of the speaker 60.

  Here, the position where the partition plates 70a and 70b are provided will be described. The internal space of the casing 3A of the electronic keyboard instrument 1A according to the present embodiment has a longer length in the height direction than the internal space of the casing 3 of the electronic keyboard instrument 1 according to the first embodiment. . Therefore, a two-dimensional natural vibration state in the height direction and the key arrangement direction is generated in the internal space of the housing 3A, and the natural vibration state excited by the driving of the speaker is larger than that in the first embodiment.

The housing portion 3A shown in FIG. 15A is a simplified view of the internal space of the housing portion 3A in a state where the partition plate 70 is not provided as viewed from the front. As shown in this figure, for example, when the fourth-order natural vibration mode SW2 is generated in the key arrangement direction, if the positions of the speakers 60a and 60b are the antinodes of the sound pressure of the natural vibration mode SW2, The speaker 60 is likely to vibrate, and the natural vibration state SW2 is likely to be excited. On the other hand, as shown in FIG. 15 (b), by providing the partition plates 70a and 70b so that the positions of the speakers 60a and 60b are located at the nodes of the sound pressure of the natural vibration state SW2, the partition plates 70a and 70b are provided. The vibration state SW2 becomes difficult to be excited.
Since the position where the speaker 60 is attached is restricted by the electronic components provided in the internal space of the housing 3A, the size of the housing 3A, and the like, it is difficult to easily change the position of the speaker. Therefore, in the housing portion 3A according to the present embodiment, the position of the sound pressure node of the natural vibration state generated in the internal space is adjusted by the partition plate 70, and the number of natural vibration states excited by the vibration of the speaker 60 is determined. It is reduced.

  FIG. 16 shows the listening sound pressure frequency characteristics at the performer position when the partition plate 70 is provided in this way. A peak occurs at a portion indicated by R1 in FIG. 16, and a dip occurs at a portion indicated by R2. As in the first embodiment, the peak is a specific frequency excited by the vibration of the speaker 60 (the frequency that becomes the broken line B in FIGS. 5B and 5C). The dip is considered to be caused by a reaction force that suppresses the vibration of the speaker 60. That is, when the sound pressure in the space behind the sound emitting surface of the speaker 60 becomes positive, the diaphragm of the speaker 60 tries to push air toward the internal space, or the sound pressure in the space behind becomes negative. It is thought that the vibration is suppressed by the reaction force that the diaphragm tries to push air toward the external space.

  The resonator 80 provided in each speaker installation space of the housing 3A according to the present embodiment is provided to suppress the peak and dip shown in FIG. Here, the structure of the resonator 80 according to the present embodiment will be described with reference to FIG. FIG. 17A is a perspective view showing the appearance of the resonator 80, and FIG. 17B is a plan view of the resonator 80 shown in FIG. FIG. 17C is a rear view of the resonator 80, and FIG. 17D is a front view of the resonator 80.

  As shown in FIG. 17A, the resonator 80 is formed by attaching a cylindrical first resonator 80 a and a second resonator 80 b to a mounting plate 81. As with the resonator 32 described in the first embodiment, the first resonator 80a and the second resonator 80b are formed of a material such as metal or synthetic resin in a tubular shape and have a hollow region. As shown in FIGS. 17B to 17D, the first resonator 80a and the second resonator 80b have openings (control points) 801a and 801b in which one end in the longitudinal direction is opened. And the other end has closed portions 811 a and 811 b closed by the attachment member 82.

  The first resonator 80a is an example of a resonator according to the present invention. The first resonator 80a has a function of reducing the sound pressure of a specific frequency excited by the vibration of the speaker 60, that is, a function of suppressing the peak indicated by R1 in FIG. The length of the hollow region of the first resonator 80a is designed to be ¼ of the wavelength of the sound wave having the frequency at which the peak is generated.

  The second resonator 80b is an example of the second resonator of the present invention. The second resonator 80b has a function of releasing a reaction force that suppresses vibration of the speaker 60, that is, a function of suppressing the dip indicated by R2 in FIG. The length of the hollow region of the second resonator 80b is designed to be ¼ of the wavelength of the sound wave having the frequency at which the dip occurs.

The place where the opening 801a of the first resonator 80a is located in each speaker installation space is the place of the antinode of the sound pressure of the natural vibration state of the frequency where the peak is generated, as in the first embodiment. Further, in each speaker installation space, the position where the opening 801b of the second resonator 80b is located is the center of the speaker 60 (speaker voice coil) by a distance of about 1/4 of the wavelength of the sound wave of the frequency at which the dip is generated. On the boundary surface away from the axis). Further, the opening 801b of the second resonator 80b is an antinode of the sound pressure of the natural vibration mode of the frequency where the dip is generated, and is a position near the baffle plate 61 to which the speaker 60 is attached. When the sound wave including the frequency enters the hollow region 801b from the opening 801b of the second resonator 80b, the second resonator 80b resonates, and the sound pressure is reduced around the frequency near the opening 801b. The reaction force of is released.
Further, in each speaker installation space, the location where the opening 801b of the second resonator 80b is located is, for example, an antinode of the sound pressure of the natural vibration state in the speaker installation space at the frequency at which the dip in FIGS. 16 and 19A occurs. And the second resonator 80b resonates at the frequency at which the dip is generated, so that the node of the sound pressure in the natural vibration state of the frequency at which the dip is generated is at the center of the speaker 60 (the speaker 60). It is also possible to set the position in the vicinity of each position) on the axis of the voice coil. Here, the vicinity of the center of the speaker 60 where the node of the sound pressure is located is preferably a region where the distance from the center of the speaker 60 is within λ / 8, where the wavelength λ of the sound wave having the frequency at which the dip is generated. . As described above, the reaction force of the speaker 60 is also released when the node of the sound pressure of the natural vibration state of the frequency where the dip is generated is located in the region within λ / 8 from the center of the speaker 60. is there.

  When the TE 49a is provided above the keyboard 41 as in the electronic keyboard instrument 1A according to the present embodiment, the opening 801a of the first resonator 80a is arranged in the horizontal direction (key arrangement) of each speaker installation space. Direction), the position closer to the side plate 48 than the position of the speaker 60, that is, the position closer to the external space, and the effect is enhanced by being installed near the center in the height direction of each speaker installation space. Have obtained by experiment. Further, the opening 801b of the second resonator 80b has a distance l (reaction against vibration of the speaker 60) from the center of the speaker 60, like the bottom side of each speaker installation space, that is, the lower internal space S2 shown in FIG. The inventors have experimentally obtained that it is desirable to install the sensor at a position on the lower boundary surface that is separated by a distance of approximately ¼ of the wavelength of the sound wave at which the force is generated. Since the natural vibration state in the housing portion 3A changes depending on the position where the TE 49a is provided, the positions of the openings of the first resonator 80a and the second resonator 80b are adjusted by experiments or the like depending on how the TE 49a is provided. It is desirable.

  The frequency characteristics shown in FIG. 19A are obtained when only the first resonator 80a is installed in each speaker installation space in the lower internal space S2 (waveform A) as shown in FIG. 19B (A). ), When only the second resonator 80b is installed in each speaker installation space in the lower internal space S2 (waveform B), each speaker in the lower internal space S2 as shown in FIG. 19B (C). The results measured by the inventors for the case where the first resonator 80a and the second resonator 80b are installed in the installation space (waveform C) and the lower internal space S2 in the lower internal space S2 as shown in FIG. FIG. 16 shows frequency characteristics when the first resonator 80a and the second resonator 80b are not installed in each speaker installation space (waveform D: the same as in FIG. 16), and a portion including R1 and R2 in FIG. Is an enlarged version.

  As shown in FIG. 19A, in the portion where the dip occurs, as shown by the waveform B in which only the second resonator 80b is installed, the speakers 60a and 60b are compared with the case where the resonator 80 is not inserted. The sound pressure of the sound wave at the frequency at which the dip was generated due to the release of the reaction force that suppresses the vibration of the dip. Further, as shown by the waveform A in which only the first resonator 80a is installed, the sound pressure of the frequency that has been excited in the portion where the peak occurs is compared with the case where the resonator 80 is not installed. Has been reduced. Then, as shown by the waveform C, when the first resonator 80a and the second resonator 80b are installed, the sound pressure at the dip portion is higher than that of the waveform B, and the peak is higher than that of the waveform A. The sound pressure of the portion is reduced, and the effect is enhanced by installing the first resonator 80a and the second resonator 80b.

  In the case of the housing 3A that can generate a two-dimensional natural vibration state, like the electronic keyboard instrument 1A according to the present embodiment, the partition plate 70 is arranged so that the position of the speaker 60 is a node of the sound pressure of the natural vibration state. By providing, the natural vibration state excited by the vibration of the speaker 60 can be reduced. Further, by providing the resonators 80 in the respective speaker installation spaces, the first resonator 80a that resonates at the excited frequency can reduce the sound pressure of the frequency, and the reaction force that suppresses the vibration of the speaker 60. The reaction force can be released by the second resonator 80b that resonates at a frequency that causes the sound pressure to increase the sound pressure of the frequency.

  In the above-described embodiment, the opening 801b of the second resonator 80b that resonates at a frequency that generates a reaction force against the vibration of the speaker 60 is lowered from the center of the speaker 60 by ¼ of the wavelength of the sound wave of the frequency. In the example described above, the dip is reduced by providing the dip, but the cause of the occurrence of the dip is the sound pressure of the natural vibration state of the frequency where the dip is generated in the vicinity of the TE 49a. The situation is possible. That is, although the natural vibration state of the frequency at which the dip is generated is excited by the vibration of the speaker 60, the sound pressure near the TE 49a is weakened, and the sound volume emitted from the TE 49a is small. Therefore, in such a case, the position near the node of the natural vibration state in the internal space of the housing 3A is such that the vicinity of the TE 49a becomes the antinode of the sound pressure of the natural vibration state of the frequency at which the dip occurs. An opening of the second resonator 80b that resonates at a frequency may be provided. With this configuration, the position of the node in the natural vibration state is forcibly generated by the opening 801b of the second resonator 80b, the sound pressure in the vicinity of the TE 49a is controlled to the belly, and the frequency at which the dip occurs Can increase the sound pressure. In this case, the second resonator 80b functions as a third resonator according to the present invention.

<Embodiment 3>
FIG. 20 shows a perspective view of the electronic keyboard instrument according to the present embodiment. The electronic keyboard instrument 501A has a keyboard unit 502A and a casing 503A that supports the keyboard unit 502A (see FIG. 22).
The keyboard unit 502A includes a plate-shaped mouth bar portion 544 extending in the horizontal direction, plate-like side plates 548 and 548 extending from the both ends of the mouth bar portion 544 to the back side, and the mouth bar portion 544 and the side plates 548 and 548, respectively. A shelf plate 553 (key support member) provided to cover the bottom of the U-shaped frame. A keyboard 541 in which white keys and black keys are arranged is arranged on a frame formed by the side plates 548 and 548, the mouth bar portion 544 and the shelf plate 553. In addition, the back of the keyboard 541 is covered, and a keyboard lid 545 is rotatably provided. Further, the beat tree unit 542 is provided with a power switch and various operation switches. When the keyboard cover 545 is opened so that the keyboard 541 can be seen, the surface of the keyboard cover 545 that is visible to the performer has a music receiver 546 and a front cover 551, and the keyboard cover 545 is turned to the performer side. In the state, the keyboard 541 is covered, and in the state shown in FIG. 20, the performance portion of the keyboard 541 is exposed. Each key of the keyboard 541 is provided with a detection switch (not shown) for detecting a key pressed by the performer. The detection switch outputs an operation signal corresponding to the detected key to a musical sound signal detection circuit 534 described later.

The casing 503A has arm portions 543 and 543 extending in the vertical direction for supporting the left and right sides of the keyboard unit 502A. The lower ends of the side plates 548 and 548 behind the arm portion 543 are connected by a plate-like bottom plate 547 (see FIG. 22), and the upper ends of the side plates 548 and 548 are connected by a plate-like roof plate 547. Has been. Back sides of these side plates 548 and 548 and the roof plate 547 are covered with a back plate (not shown). The front plate 549 is attached so as to cover from the upper end portion of the roof plate 547 to the rear portion of the keyboard. Further, the shelf board 553 is supported from below by the front leg portions 550 and 550. Note that the tone signal detection circuit 534 is disposed inside the housing portion 503A.
A speaker box 580 is installed under the shelf board 553. The speaker box 580 is fixed to the left and right side plates 548 and 548, and is installed so that the front plate 581 of the speaker box 580 does not protrude forward from the front end portion of the side plate 548. The internal space 582 of the speaker box 580 is divided into two in the left-right direction by the partition plate 570, and each is formed as internal spaces 582a and 582b (see FIG. 23). In the internal spaces 582a and 582b of the speaker box 580, rear portions of speakers 560a and 560b described later are respectively positioned. Further, the front plate 581 is provided with sound emitting holes and saran nets 551a and 551b for emitting musical sounds from the speakers 560 at positions corresponding to the speakers 560, respectively. A TE 581a is provided above the portion of the front plate 581 where the saran nets 551a and 551b are provided. The internal space 582a of the speaker box 580 has a property almost similar to a closed space, but air can enter and exit from the outside via the TE 581a. Accordingly, the sound emitted from behind the sound emitting surface of the speaker 560 is guided to the outside through the internal space 582a and the TE 581a. Below the speaker box 580, a lower front plate 552b is provided. The lower front plate 552b extends downward so as to be substantially flush with the front plate 581 of the speaker box 580.
Further, the front leg portions 550 and 550 are provided so as to protrude from the vicinity of the bottom portions of the arm portions 543 and 543 toward the performer, and the housing portion 503A is stably standing by the front leg portions. . The pedal unit 504A is housed in the center of the lower front plate 552b with each pedal protruding toward the performer.

  Here, the internal structure of the housing portion 503A will be described. 21 is a front view of the electronic keyboard instrument 501A shown in FIG. 20, and FIG. 22 is a cross-sectional view of the electronic keyboard instrument 501A when cut along the cutting line XXII-XXII in FIG.

  The speaker 560 is attached so that the sound emitting surface faces the player side, and a sound emitting hole 562 is provided in the front plate 581 at a position corresponding to the sound emitting surface. The sound emitted from the speaker 560 is propagated to the performer through the hole 562 (third sound emission path W3). In addition, the sound emitted from behind the speaker 560 is propagated to the performer side through the TE 581a provided on the front plate 581 via the internal space 582a of the speaker box 580 (fourth sound emission path W4). ).

  FIG. 23 is a diagram for explaining the position of the speaker 560 and the arrangement position of the resonator 590 in the internal space 582 of the speaker box 580. The resonator 590 includes a cylindrical third resonator 590a (an example of a second resonator) and a fourth resonator 590b (an example of a second resonator), each fixed to the wall of the speaker box 580. And installed in the internal spaces 582a and 582b. Further, the third resonator 590a and the fourth resonator 590b have openings 591a and 591b (open ends) in which one end in the longitudinal direction is opened, and a closed portion in which the other end is closed. 592a and 592b (closed end portions).

  The third resonator 590a has a function of reducing the sound pressure of a specific frequency excited by the vibration of the speaker 560, that is, a function of suppressing the dip shown by R2 in FIG. The length of the hollow region of the third resonator 590a is designed to be ¼ of the wavelength of the sound wave having the frequency at which the dip occurs.

  The fourth resonator 590b has a function of reducing the sound pressure of a specific frequency excited by the vibration of the speaker 560, that is, a function of suppressing the dip shown by R2 in FIG. The length of the hollow region of the fourth resonator 590b is designed to be ¼ of the wavelength of the sound wave having the frequency at which the dip occurs.

  In the internal space 582 in which each speaker 560 is installed, the position where the opening 591a of the third resonator 590a is located is the position of the antinode of the sound pressure of the natural vibration state of the frequency at which the dip is generated. The location where the opening 591b of the resonator 590b is located is the position of the antinode of the sound pressure of the natural vibration mode of the frequency where the dip is generated. When the sound wave including the frequency where the dip is generated from the openings 591a and 591b of the third resonator 590a and the fourth resonator 590b enters the hollow region, the third resonator 590a and the fourth resonator 590b resonate. In the vicinity of the openings 591a and 591b, the sound pressure is reduced around the frequency, and the reaction force of the speaker 560 is released. This will be described with reference to FIG. FIG. 24A shows a state of sound pressure in a natural vibration state of a frequency where a dip occurs when the resonator 590 is not provided in the internal space 582, and FIG. 24B shows resonance in the internal space 582. The state of the sound pressure of the natural vibration state of the frequency where the dip is generated when the body 590 is disposed is shown. As shown in FIG. 24A, when the sound pressure antinode of the natural vibration state of the frequency fd where the dip is generated is present in the vicinity of the speakers 560a and 560b, the dip as indicated by R2 in FIG. 16 is generated. Conceivable. When the resonator 590 is disposed in the internal space 582 of such a speaker box 580, the resonator 590 is resonated by positioning the opening 591 at the antinode of the sound pressure of the natural vibration state of the frequency fd, and the frequency The sound pressure of fd is reduced, the reaction force of the speaker 560 is released, and the dip of the frequency fd is suppressed. Specifically, in FIG. 24B, the locations where the openings 591a and 591b of the third resonator 590a and the fourth resonator 590b are placed in each speaker installation space, for example, the dip in FIG. 16 or FIG. 19A occurs. It is a place of the antinode of the natural vibration state in the speaker box at the frequency fd, and the third resonator 590a and the fourth resonator 590b resonate at the frequency fd, so that the sound wave of the natural vibration state of the frequency fd The position is such that the size Si becomes smaller.

  Also, as shown in FIG. 24C, the locations where the openings 591a and 591b of the third resonator 590a and the fourth resonator 590b are located in the respective speaker installation spaces are the locations of the antinodes of the sound pressure of the natural vibration state of the frequency fd. When the third resonator 590a and the fourth resonator 590b resonate at the frequency fd, the sound pressure node of the natural vibration state of the frequency fd becomes the center Ps of the speakers 560a and 560b (the speaker voice coil). It is also possible to set the position in the vicinity of each position) on the axis. Here, in the vicinity of the center Ps of the speaker 560 where the node of the sound pressure is located, a region where the distance from the center Ps of the speaker 560 is equal to or less than λ / 8 (λ is the wavelength of the sound wave in the natural vibration state of the frequency fd) is less than or equal to. desirable. As described above, the reaction force of the speaker 560 is also released when the node of the sound pressure is located in the region within λ / 8 from the center Ps of the speaker 560. According to this, as shown in FIG. 24A, when the antinode of the sound wave having the natural vibration state with the frequency fd exists at the center position Ps of the speaker 560, the openings 591a and 591b of the resonator 590 have the natural vibration state with the frequency fd. Are arranged so that the distance from the center Ps is less than λ / 8.

  The explanation will be continued. FIG. 24A illustrates a state of standing waves generated in the speaker box when the third resonator 590a and the fourth resonator 590b are not present in the speaker box. FIG. 24C shows a state in which standing waves are present in the speaker box as shown in FIG. 24A, and the openings 591a and 591b of the third resonator 590a and the fourth resonator 590b are arranged at the center Ps of the speakers 560a and 560b. The natural vibration mode (mode) of the standing wave changes by being placed in the vicinity, and the natural vibration mode of the standing wave is changed so that the position of the center Ps of the speakers 560a and 560b becomes the position of the node of the standing wave. It represents a changed state. When the third resonator 590a and the fourth resonator 590b are placed at a position where the standing wave is in such a natural vibration state, the vibration film of the speaker 560 is easily vibrated, and the dip shown in FIGS. The effect of becoming smaller can occur. As shown in FIG. 24A, when the antinode of the sound wave having the natural vibration state with the frequency fd exists at the center position Ps of the speaker 560, the positions of the third resonator 590a and the fourth resonator 590b and the centers Ps of the speakers 560a and 560b If the position difference is up to λ / 8, it is considered that the above action can occur practically. Therefore, it is desirable to arrange the opening 591 of the resonator 590 within the range of λ / 8 from the center Ps of the speaker 560. It is.

Further, as a modification of the present embodiment, the resonator 590 can be arranged at a position as shown in FIG. 25B. That is, as shown in FIG. 25A, the resonator 590 is the position of the antinodes of the sound pressure of the natural vibration state at the frequency where the dip occurs when the resonator 590 is not provided, and the speaker 560a and By arranging the openings 591a and 591b of the third resonator 590a and the fourth resonator 590b at positions away from the center Ps of 560b, as shown in FIG. It is possible to suppress the generation of dip by reducing the size Si of the sound wave in the vibration state.
Further, as shown in FIG. 25C, the openings 591a and 591b are located at the positions of the antinodes of the sound pressure of the natural vibration at the frequency where the dip is generated, and away from the center Ps of the speakers 560a and 560b. By disposing, as shown in FIG. 25C, the node of the natural vibration mode of the frequency where the dip is generated may be positioned near the center Ps of the speakers 560a and 560b, and the generation of the dip may be suppressed.

<Modification>
Hereinafter, modifications of the above-described embodiment will be described.
(1) Although the example which installs the four resonators 32 in the internal space of the housing | casing part 3 which concerns on Embodiment 1 mentioned above was demonstrated, you may comprise as follows. FIG. 26 is a simplified view of the internal space of the housing unit 3 as viewed from above. As shown in FIG. 26A, the resonator 32 is not provided, and the partition plate 70 is provided between the speakers 30a and 30b so that the positions of the speakers 30a and 30b are nodes of the sound pressure of the natural vibration state in the internal space. May be provided. In addition, as shown in FIG. 26 (b), a partition plate 70 is provided in the same manner as in FIG. 26 (a), and in each space partitioned by the partition plate 70, the sound pressure bellows of the natural vibration state in the space is provided. You may make it arrange | position the resonator 32a so that the opening part 321 of the resonator 32a may be located in a place.

(2) The arrangement of the first resonator 80a and the second resonator 80b provided in the internal space of the housing 3A according to the second embodiment described above is not limited to the mode described in the second embodiment, and the following mode is used. It may be. FIG. 27 is a simplified view of the lower internal space of the housing 3 </ b> A according to this modification as viewed from the front. In FIG. 27A, the partition plate 70 is not provided, and each set of two first resonators 80a and two second resonators 80b is provided at predetermined positions above and below the speakers 60a and 60b. It is. The opening 801a of the first resonator 80a and the opening 801b of the second resonator 80b provided on the speaker 60a side are directed in the direction of the arrow L. The opening 801a of the first resonator 80a and the opening 801b of the second resonator 80b provided on the speaker 60b side are directed in the direction of the arrow R. As in the second embodiment, the positions of the openings 801a of the first resonators 80a are the positions of the antinodes of the sound pressure of the natural vibration state of the excited frequency, and the openings of the second resonators 80b. The position 801b is on the boundary surface that is separated from each gravity center position of the speakers 60a and 60b by a distance of 1/4 of the wavelength of the frequency that generates a reaction force that suppresses vibration of the speakers 60a and 60b.

  Moreover, in the arrangement of the first resonator 80a and the second resonator 80b shown in FIG. 27A, a partition plate may be provided as shown in FIGS. 27B and 27C. In the case of FIG. 27B, only one partition plate 70 is provided. In this case, for example, the partition plate 70 may be provided so that the position of the speaker 60a becomes a node of sound pressure in the natural vibration state. That is, by providing the partition plate 70 so that the position of at least one speaker is a node of the sound pressure of the natural vibration state, the number of natural vibration states excited by the vibration of the speaker may be reduced.

  Further, as shown in FIG. 27 (d), resonators 80c and 80d may be provided between the partition plates 70a and 70b in the arrangement shown in FIG. 27 (c). Similar to the first resonator 80a and the second resonator 80b, the resonators 80c and 80d have an opening and a hollow region. The opening of the resonator 80c is disposed downward, and the opening of the resonator 80d is disposed upward. The resonator 80c may resonate at the same frequency as the second resonator 80b, or the resonator 80d may resonate at the same frequency as the first resonator 80a. The resonator 80c and the resonator 80d may resonate at other frequencies.

(3) The casing of the electronic keyboard instrument according to the embodiment described above may have a shape as shown in FIG. Similar to the first embodiment, such as a rectangular parallelepiped shape such as the housing portion 3B shown in FIG. 28A, or a shape having a polygonal top and bottom surfaces like the housing portion 3C shown in FIG. The shape of the casing may be such that a one-dimensional natural vibration state occurs in the key arrangement direction in the internal space of the casing. In this case, the speaker 30 may be arranged so that the sound emitting surface of the speaker 30 faces the bottom surface direction or the top surface direction of the housing unit. Moreover, a rectangular parallelepiped shape like housing | casing part 3D shown in FIG.28 (c) may be sufficient. That is, as in the second embodiment, any shape other than the second embodiment may be used as long as a two-dimensional natural vibration state is generated in the height direction and the key arrangement direction. In this case, you may arrange | position so that the sound emission surface of the speaker 60 may face a player side or a back side.

(4) In each of the above-described embodiments, an example in which a tubular resonator is used has been described. However, various resonators such as plate vibration resonance, Helmholtz resonance, bent plate vibration, and piston plate vibration may be used. In short, the resonator is a resonator designed in consideration of the coupling with the sound field in the internal space of the casing of the electronic keyboard instrument, and controls the acoustic energy in the internal space of the casing. I just need it. Specific examples of the resonator are shown below.

  FIG. 29A is a diagram schematically showing the appearance of the plate vibration resonator. FIG. 29B is a cross-sectional view of the plate vibration resonator 110 viewed from the arrow VI-VI in FIG. The plate vibration resonator 110 includes a housing part 110A and a vibration part 110B. The casing 110A is a rectangular parallelepiped box-like member that is open on the entire upper surface side. The casing 110A has an opening 110C and a rectangular parallelepiped gas layer 110D as a hollow area communicating with the opening 110C. The housing part 110A is made of, for example, wood, but other materials such as synthetic resin and metal may be used as long as the material is relatively harder than the vibration part 110B. The vibration unit 110B is a rectangular member having elasticity and formed in a plate shape or a film shape. For the vibration part 110D, for example, a material that has elasticity and generates elastic vibration such as synthetic resin, metal, fiberboard, closed cell foam, etc. is formed into a plate shape, or an elastic material or polymer compound is formed into a film. What was formed in is used. The vibration part 110B is provided so that the area near the end of one surface thereof is supported by the housing part 110A and closes the opening 110C of the housing part 110A. By closing the opening 110C with the vibration part 110D, a closed gas layer 110D is formed inside the plate vibration resonator 110. The gas layer 110D is a layer made of gas particles. In this example, the gas layer 110D is an air layer made of air molecules, but an elastic body such as a porous material may be provided on the gas layer 110D. The plate vibration resonator 110 is provided so that the vibration part 110B is located at the antinode of the sound pressure of the sound wave of the target frequency. When sound is generated in the space, the plate vibration resonator 110 resonates according to the sound pressure of the sound. This resonance causes a difference between the sound pressure in the space and the pressure in the gas layer 110D of the plate vibration resonator 110. The vibration unit 110B vibrates due to this pressure difference, and after the acoustic energy is consumed, the acoustic energy is re-radiated. By this action, the sound pressure is reduced in the space on the surface of the plate vibration resonator 110 and in the vicinity of the vibration part 110B surface.

FIG. 30A is a diagram schematically showing the appearance of the Helmholtz resonator, and FIG. 30B is a cross-section of the Helmholtz resonator 120 viewed from the arrow VIII-VIII in FIG. FIG. The Helmholtz resonator 120 includes a body portion 120A and a tube portion 120B. In the Helmholtz resonator 120, a space formed in the trunk portion 120A and the tube portion 120B becomes a hollow region, and the hollow region communicates with the opening 120C.
The body 120A has a gas layer formed therein, and is formed in a cylindrical shape by, for example, FRP (fiber reinforced plastic). The tube portion 120B is a tubular member having a so-called opening at both ends made of, for example, vinyl chloride, and is inserted into a hole portion of the trunk portion 120A so as to be connected to each other. The Helmholtz resonator 120 is provided so that the opening 120C is located at the antinode of the sound pressure of the sound wave of the target frequency. As a result, sound enters the opening 120C, the Helmholtz resonator 120 resonates, and the sound pressure near the opening 120C is reduced. That is, the Helmholtz resonator 120 forms a spring mass system in which the gas inside the tube portion 120B is a mass component and the gas layer of the trunk portion 120A is a spring component. Sound energy is converted into heat energy by friction between the inner wall of the tube portion 120B and air, reducing the sound pressure near the opening 120C and increasing the particle velocity. Note that the resonance frequency f of the spring mass system of the Helmholtz resonator 120 satisfies the relationship of Expression (2). However, in Formula (2), Le represents the effective length of the pipe part 120B. As shown in FIG. 30B, the effective length Le is a length obtained by correcting the length from one end to the other end of the cavity of the pipe portion 120B with the opening end correction value. V is the volume (that is, volume) of the gas layer formed in the trunk portion 120 </ b> A, and So is the area of the opening 33.
f = c0 / 2π · (So / Le · V) 1/2 (2)
In addition, although the number of the pipe parts 120B is one here, you may make it provide multiple. Further, the opening 120C of the tube portion 120B or the vicinity thereof may be blocked with a flow resistance material having air permeability such as glass wool, cloth, gauze, etc. and having flow resistance.

  FIG. 31 is a diagram showing a resonator according to this modification. FIG. 31A is a diagram illustrating an appearance of a resonator according to this modification. The external appearance of the resonator 130 is open at one end (left side in the figure) and closed at the other end (right side in the figure). The configuration of the resonator 130 is roughly divided into a tubular member 130A and a resistance material 130B. The tubular member 130A is an example of a housing of the present invention, and is formed in a cylindrical shape using, for example, metal or plastic as a material. The tubular member 130A is a so-called one-end opening tubular member, and extends in one direction here. The resistance material 130B is a member having a shape in which a cylindrical cavity is opened so as to penetrate the vicinity of the center of both bottom surfaces of the cylinder. The resistance material 130B is provided in the vicinity of the open end of the tubular member 130A so that the surface corresponding to the outer peripheral surface of the column is in contact with the inner surface of the tubular member 130A. The resistance material 130B is formed using urethane foam, which is an example of a porous material, and is a member that resists the movement of gas particles (here, air molecules) and inhibits the movement of the gas particles. It is. In the region where the resistance material 130B is disposed, the resistance to the movement of the gas particles is increased as compared to when the resistance material 130B is not disposed. Further, as a physical quantity that quantitatively represents the resistance value of this resistor, there is a characteristic impedance of the medium.

FIG. 31B is a diagram illustrating a cross section when the resonator 130 is cut along the cutting line II-II in FIG. That is, FIG. 31B is a cross-sectional view of the acoustic resonator 10 cut along a plane including the x-axis described later along the extending direction of the tubular member 130A. FIGS. 31C and 31D are views showing a cross section when the resonator 130 is cut along a plane orthogonal to the extending direction of the tubular member 130A. In addition, when each position where the resistance member 130B is provided with respect to the extending direction of the resonator 130 is cut, the cross-sectional shape of the tubular member 130A is the same,
And have the same dimensions. Further, the cross-sectional shape of the resistance material 130B is also the same shape and the same size. The tubular member 130A has a circular open end 131 at one end and the same circular closed end 132 at the other end. The closed end 132 is considered to behave acoustically in the same manner as a fully reflective surface (ie, a rigid wall). A cylindrical hollow region 130 </ b> C extending between the open end 131 and the closed end 132 is formed inside the tubular member 130 </ b> A. The hollow region 130 </ b> C communicates with the external space through the open end 131. Here, let L be the length between both ends of the hollow region 130 </ b> C, which is the distance between the open end 131 and the closed end 132. And
A line connecting the centers of the cross sections orthogonal to the extending direction of the hollow region 130 </ b> C is defined as “center axis x” (illustrated by a one-dot chain line). The diameter of the open end 131 of the tubular member 130A is sufficiently shorter than the wavelength of the resonance frequency of the resonator 130 (for example, 1/2 or less). Thereby, when the tubular member 130A is a single body, the sound wave traveling to the hollow region 130C can be regarded as only the plane wave traveling in the direction along the central axis x. Therefore, in the hollow region 130 </ b> C, the sound pressure is substantially uniformly distributed in a region having the same position in the direction along the central axis x, that is, a region included in a cross section orthogonal to the central axis x. The resistance material 130B has the position of the opening end 131 as one end,
It is provided in the hollow region 130C. Here, the resistance material 130B has a longitudinal direction along the central axis x direction. This is the length of the resistance material 130B in the longitudinal direction, and the distance from one end to the other end located at the opening end 131 is defined as l0. Since the resistance member 130B has a cavity penetrating in a direction corresponding to the length direction of the cylinder, the open end 131 and the closed end 132 of the tubular member 130A communicate with each other through this cavity. This cavity is here the region where no member is provided which increases the resistance to the movement of the gas particles. The resonance frequency of the resonator 130 shifts to a lower frequency side as the length l0 of the resistance material 130B is larger, that is, as the length L-l0 of the hollow region 130C is smaller.

(5) Moreover, the adjustment mechanism for adjusting the resonance frequency of the said resonance body may be provided in the resonance body. Even when the resonance body provided with the adjustment mechanism that adjusts the resonance frequency is used as the resonance body provided in the casing of the electronic keyboard instrument, the adjustment mechanism can be used even when the sound pressure of the natural vibration state having a plurality of different frequencies is reduced. Therefore, it is only necessary to adjust the resonance frequency by using a resonator having a common shape and size. Hereinafter, an example of such an adjustment mechanism will be described.

(A) For example, in the case of a tubular resonator as in Embodiment 1 or Embodiment 2 described above, a porous material such as urethane foam is used as an example of an adjustment mechanism that adjusts the length of the hollow region of the resonator. It is formed by using a member that resists the movement of gas particles (here, air molecules) and inhibits the movement of the gas particles by adhering to the closed portion of the hollow region of the resonator. The length may be changed. As the length of the hollow region is increased, the resonance frequency is shifted to the lower frequency side.

(B) As an example of the adjustment mechanism, as shown in FIG. 32A, for example, in the cylindrical resonator 200 similar to the second embodiment, the position of the closed portion 210 is adjusted to adjust the position of the hollow region 211. A columnar member 212 for adjusting the length may be provided. In this case, the member 212 has the same outer peripheral diameter as the inner peripheral diameter of the hollow region 211, and a hole having the same size as the outer periphery of the member 212 is provided on the surface where the member 212 of the resonator 200 is inserted. ing. Further, a screw thread and a thread groove are respectively provided on the inner periphery of the hollow region 211 and the outer periphery of the cylindrical member 212, and the member 212 is fitted into the hollow region 211 by fastening the screw thread and the screw groove. By rotating the member 212 with respect to the resonator 200, the length L of the hollow region is adjusted. The resonance frequency is shifted to the lower frequency side as the length L of the hollow region 211 becomes longer.

(C) As an example of the adjustment mechanism, as shown in FIG. 32 (b1), for example, as in the second embodiment, a cylindrical resonator 310 having one end opened and the other end closed is flexible. It has a side surface 311 in which the material is formed in a bellows shape, and the length L of the hollow region 313 is increased by moving the closing portion 312 upward as shown in FIG. 33 (b2). The resonance frequency is shifted to the lower frequency side as the length L of the hollow region 313 increases.

(D) Further, as an example of the adjustment mechanism, for example, the length of the hollow region in the tube portion in which the surface on the closed portion side of the resonator according to the first embodiment is opened and the outer peripheral surface on the closed portion side is provided with a thread. The adjustment may be performed by a lid member that has a screw groove that fits into the thread and closes the surface on the closing portion side. FIG. 32 (c1) is a view showing a cross section of the tube portion 320A. 320 A of pipe parts have a hollow area | region of length L, and have the opening part 321 and the opening part 323A used as the closing part side. A thread having a predetermined length is provided on the outer peripheral surface of the tube portion 320A on the closing portion side. 32 (c2) and 32 (c3) are diagrams showing examples of the lid member. As shown in FIGS. 32 (c2) and (c3), the cover members 320B and 320C are provided with thread grooves that fit into the threads of the tube portion 320A, and the diameter d (tube portion) of the hollow region of the tube portion 320A. A protrusion 324 having a diameter slightly smaller than the distance x2) from the axial center of 320A to the inner periphery of the tube portion 320A is provided. The lengths of the protrusions 324 of the lid member 320B and the lid member 320C are different from l1 and l2 (l1> l2).
By fitting the protrusions 324 of the lid members 320B and 320C into the opening 323A on the closing portion side of the tube portion 320A, the closing portion side of the tube portion 320A is closed to form the closing portion. For example, when the lid member 320B is fitted into the tube portion 320A by the length l1 of the protrusion 324, the length of the hollow region of the tube portion 320A is (L-l1). When the cover member 320C is fitted into the tube portion 320A by the length 12 of the protrusion 324, the length of the hollow region of the tube portion 320A is (L-12), and the cover member 320B is attached to the tube portion 320A. The length of the hollow region becomes longer than when fitting. In this manner, the resonance frequency of the resonator can be adjusted by adjusting the length of the hollow region of the tube portion 320A with a plurality of lid members having different lengths of the protrusions 324. Moreover, you may adjust the length of the hollow area | region of the pipe part 320A by changing the length which fits the projection part of each cover member in the pipe part 320A. In addition, in the state where the cover members 320B and 320C shown in FIGS. 32 (c2) and 32 (c3) are fitted into the tube portion 320A by the length of the protruding portion 324, the length in the longitudinal direction of the resonator is apparent. It will be the same length. For this reason, it is possible to reduce a useless space when a resonator, an electronic component, or the like is arranged in the internal space of the housing unit 3.

(E) In the above-described modified examples (a) to (d), the example in which the resonance frequency of the resonator is adjusted by adjusting the length of the hollow region of the tubular resonator has been described. The resonance frequency may be adjusted by adjusting the volume of the hollow region without changing the length of the hollow region of the body. FIG. 32 (d <b> 1) is a diagram showing a cross section of the resonator according to this variation. As shown in FIG. 32 (d1), the resonator 330 has a tubular shape having a hollow region P1 that is open at one end and closed at the other end. An opening 331 having a diameter d1 is provided in a part of the side surface of the resonance body 330. In this figure, the opening 331 is closed by a member 331A. The member 331A for closing the opening 331 is configured to be detachable. When adjusting the resonance frequency of the resonator 330, as shown in FIG. 32 (d2), the member 331A is formed on the outer peripheral surface instead of the member 331A. A tubular member 332 provided with a thread and having both ends opened is bonded to the end of the opening 331, and has the same shape as that shown in FIGS. 32 (c2) and 32 (c3). The lid member 333 having a thread groove to be fitted to is connected to the tubular member 332. In a state where the lid member 333 is connected to the tubular member 332, a space P2 from the opening 331 connected to the hollow region P1 to the protrusion of the lid member 333 is formed, and the volume of the hollow region of the resonator 330 is increased. As the volume of the hollow region of the resonator 330 increases, the resonance frequency of the resonator 330 is shifted to the low frequency side.
As a preferred example of using the above-described resonator shown in FIG. 32, when the same resonator is used in a plurality of models having different housing structures, or when the acoustic characteristics change due to the arrangement or addition of internal components due to a product design change. It is mentioned that it can respond easily.

(F) Next, FIG. 33 shows an example of a Helmholtz resonator including an adjustment mechanism. The Helmholtz resonator 410 shown in FIG. 33 (a) includes a body 410A and a tube 410B, similar to the Helmholtz resonator 120 described above. The trunk portion 410A has a bowl shape having a neck portion 411, and the neck portion 411 has a pipe line having the same outer peripheral diameter as the inner peripheral diameter of the pipe portion 410B. A screw thread and a thread groove are respectively provided on the inner periphery of the tube portion 410B and the outer periphery of the neck portion 411, and the tube portion 410B and the tube portion 410B of the trunk portion 410A are fitted by fastening of the screw thread and the screw groove. The By rotating the body portion 410A with respect to the tube portion 410B, the tube length L composed of the neck portion 411 and the tube portion 410B is adjusted. As the tube length L becomes longer, the resonance frequency of the Helmholtz resonator 410 is shifted to the lower frequency side. The side surface of the tube part 120B of the Helmholtz resonator 120 is formed in a bellows shape as shown in (c) above, and the body part 120A is moved to change the length of the tube part 120B. The length of the 120B hollow region may be adjusted.

  In the Helmholtz resonator 410 shown in FIG. 33 (a), the resonance frequency is adjusted by adjusting the tube length L. However, the resonance frequency may be adjusted by adjusting the volume of the body 410A. Good. FIG. 33B shows an example of a Helmholtz resonator 420 having an adjustment mechanism for adjusting the volume of the body portion. The Helmholtz resonator 420 includes a body 420A having a hollow region 422 and a tube 420B having an opening 421 in contact with the external space and a pipe 423 that leads from the opening 421 to the hollow region 422 of the body 420. Yes. A screw thread is provided on the inner peripheral surface of the body portion 420A, and a columnar member 420C is inserted into a hole provided in the bottom surface of the body portion 420A. The member 420C has the same outer diameter as the inner diameter of the body portion 420A, and a screw groove that fits the screw thread is provided on the outer periphery. The volume of the hollow region 422 of the trunk portion 420A is increased by rotating the member 420C with respect to the trunk portion 420A and moving the member 420C in a direction in which the member 420C is in contact with and away from the trunk portion 420A. As the volume of the hollow region 422 of the body 420A increases, the resonance frequency is shifted to the lower frequency side. As shown in FIGS. 33A and 33B, the Helmholtz resonator may be provided with either an adjustment mechanism for adjusting the tube length or an adjustment mechanism for adjusting the volume of the hollow region of the body portion. However, both adjustment mechanisms may be provided.

  Further, an adjustment mechanism for adjusting the inner diameter of the tube portion 120B of the Helmholtz resonator 120 may be provided. As an adjustment mechanism, for example, a cylindrical member having the same outer diameter as the hollow region of the tube part 120B and the same length as the hollow region of the tube part 120B and having both ends opened is a tube. Attached to the part 120B, the diameter of the pipe part 120B is reduced. The resonance frequency shifts to the lower frequency side as the inner diameter of the tube portion 120B becomes smaller. In addition, as an adjustment mechanism that adjusts the resonance frequency of plate vibration resonators, bent plate vibration resonators, etc., a plate-like material that has elasticity and generates elastic vibration, such as synthetic resin, metal, fiberboard, closed cell foam, etc. An additional material such as a weight may be provided on the diaphragm formed in the above. The additional member may be attached to a region including a position where the amplitude becomes maximum when the vibration plate is bent and vibrated. As the mass of the diaphragm increases, the resonance frequency of the bending system shifts to the low frequency side.

(6) In the second embodiment described above, the example in which the partition plate 70 is provided has been described. However, by arranging an electrical component such as a circuit board at the position of the partition plate 70, the electrical component may be used as the partition plate. Good. In the second embodiment, the example in which the resonator 80 is attached to the inner wall of the back plate 55 has been described. However, other members (the inner wall of the front plate 49, the shelf plate 53) provided in the internal space of the housing 3A. And the like may be formed integrally with the bottom surface. For example, as shown in FIG. 34, a partition / resonance member in which a resonator and a partition plate are integrally formed may be used. FIG. 34A is a simplified diagram showing a speaker installation space. As shown in FIG. 34 (b), in the partition / resonance member 700, in the installed state, the surface 712 located on the speaker 60a, 60b side is shorter than the surface 711 facing the surface 712, and the bottom 710a is formed. It has a rectangular parallelepiped shape that is opened and the upper portion 710b is closed, and a hollow region 713 is provided inside. For example, when the partition / resonance member 700 is caused to function as the second resonator, the surface 712 is such that the length L of the hollow region 713 is ¼ of the wavelength of the frequency to be reduced in sound pressure. Design the length of.

(7) A tabletop electronic piano as shown in FIG. 35 may be applied as the electronic keyboard instrument according to the first embodiment. In this figure, a keyboard 11 is provided on the casing 3E of the electronic keyboard instrument 1, and a TE 17a is provided on the top of the keyboard 11. The speaker 30 is provided in the internal space of the housing 3E so that the sound emitting surface is in the upper surface direction, and the resonator 32 is provided in a space below the speaker 30. In the internal space of the housing 3E, the space in which the speaker 30 is provided and the space in which the keyboard 11 is provided are connected, and the housing 3E transmits sound from the speaker 30 from the sound emitting surface to the external space. The sound of the speaker 30 is propagated from the gap between the TE 17a and the key of the keyboard 11 to the external space via the first sound emission path to be propagated to and the space behind the speaker 30, that is, the space below the speaker 30. 2 sound emission paths. As in the first embodiment, the position of the opening of the resonator 32 is the place of the antinodes of the sound pressure of the natural vibration mode of the frequency to be reduced in the space where the speaker 30 is provided. Note that the second sound emission path includes a sound emission path through which sound is propagated from the gap between the upper case and the lower case of the electronic keyboard instrument toward the keyboard 11 or the back side. You may do it.

(8) As described above, the tubular resonator according to the embodiment and the modification is a tube having a uniform cross section perpendicular to the longitudinal direction at an arbitrary position extending in the longitudinal direction, and one end thereof. It can be said that it is an acoustic damper body made of a tube material having a shielding end that acoustically shields. Further, the Helmholtz resonator according to the embodiment and the modification described above is a container having a hollow portion, where one end of the hollow portion is opened and a portion recessed from the one end toward the other end is the one. It can be said that it is an acoustic damper body provided with a cave portion having an area larger than the open area opening area of the end. Further, the Helmholtz resonator in a narrow sense is an acoustic in which a cave portion having a predetermined length in the depth direction from the one end has a uniform cross section, and a further back portion has a cave portion larger than the cross-sectional area of the cross section. It can be said that it is a damper body. In short, the resonator according to the embodiment and the modification described above is defined as an acoustic damper body having one end opened and having a cave in a direction deeper from the one end.

(9) In the embodiment and the modification described above, the example in which the electronic keyboard instrument is provided with the TE has been described, but an electronic keyboard instrument in which the TE is not provided may be used. In short, it has a second sound emission path for propagating the sound of the speaker to the external space from a path acoustically communicating outside the casing, such as a key gap of the keyboard, via the internal space of the casing in which the speaker is provided. Electronic keyboard instruments may be used. Further, the second sound emission path for propagating the sound of the speaker to the external space via the internal space of the housing in which the speaker is provided is not limited to the gap between the TE and the key on the keyboard. For example, an electronic guitar equipped with a speaker inside and having a path for guiding the sound behind the sound emitting surface to the outside, an electronic stringed instrument such as an electronic violin, a speaker, and the sound behind the sound emitting surface are guided outside. The present invention may be applied to an electric percussion instrument such as a percussion provided with an electric stringed instrument such as an electric guitar having a path, a speaker, and having a path for guiding the sound behind the sound emitting surface to the outside.

(10) In Embodiment 2 and Modification 2 described above, an example in which one speaker is provided in each of the spaces partitioned in the lower internal space S2 of the housing 3A has been described. For example, FIG. As shown in (a), a plurality of speakers 60a and 60b may be provided in each of the partitioned spaces S21 and S21. Further, as shown in FIG. 36 (b), a speaker 60c may be provided in a space where the resonator 80 is not provided in the lower internal space S2. Further, as shown in FIG. 36 (c), in the lower internal space S2, two speakers 60a are provided in one space S22 in which the resonator 80 is provided, and three speakers 60b are provided in the other space S23. May be provided. In short, if the internal space is partitioned so that two or more speakers are divided into at least two sets, and the resonator 80 is provided in any two or more of the partitioned spaces where the speakers are located. Good.
In the above-described embodiment, an example in which two speakers are provided in the casing has been described. However, the number of speakers is not limited to this, and may be larger or smaller. That is, it is only necessary that at least one speaker is provided in the housing.

(11) In Embodiment 2 described above, an example of an electronic keyboard instrument has been described. However, the present invention can be applied to any acoustic system having a speaker having a sound emission path that guides vibration from the back surface of the sound emission surface of the speaker to the outside. . For example, you may apply to the speaker box etc. which are mounted in a motor vehicle. Specifically, the housing structure has a complicated shape, and the sound generated in the housing includes a first resonator that reduces sound pressure in a natural vibration state of at least one specific frequency, and further includes the specific What is necessary is just to provide the resonance body which reduces the reaction force with respect to the motion of a speaker produced in the frequency different from a frequency.

1, 1A, 501A ... electronic keyboard instrument, 2, 2A, 502A ... keyboard unit, 3, 3A, 3B, 3C, 3D, 3E, 503A ... casing, 4, 4A, 504A ... Pedal unit 11, 41, 541 ... keyboard, 11a ... front plate, 12 ... operation panel, 13, 43, 543 ... arm part, 14, 44, 544 ... mouth stick part, 15 , 45, 545... Keyboard cover, 16... Music board, 17 .. roof board, 17 a, 49 a, 581 a.
Tone escape (acoustic relief / TE), 18, 48, 548 ... side plate, 19, 53, 553 ... shelf plate, 20, 55 ... back plate, 21 ... bottom member, 22. ..Tsum base, 30, 30a, 30b, 60, 60a, 60b ... Speaker, 32, 32a, 32b ... Resonator, 34, 90 ... Substrate, 42, 542 ... Time signature, 46 ...・ Musical score holders, 50, 550... Front legs, 51a, 51b, 551a, 551b... Saran net, 61... Baffle plates, 70, 70a, 70b, 570. 310 ... resonator, 80a ... first resonator, 80b ... second resonator, 110 ... plate vibration resonator, 120,410 ... Helmholtz resonator, 549 ... front plate, 580 ... Speaker box, 581 ... Front plate 582a, 582b ... internal space, 700 ... partition-resonant members, W1 ... first sound emission path, W2 ... second sound emission path

Claims (1)

A case, a keyboard supported in an exposed state from the case, a tone generation circuit that generates a tone signal according to an operation of the keyboard, and a speaker that emits a tone signal generated by the tone generation circuit; In an electronic keyboard instrument in which the musical sound generating circuit and the speaker are housed in an internal space of the housing,
The housing has a first sound emitting path for guiding the sound emitted from the sound emitting surface of the speaker to the outside and propagating the sound outside the housing; and the sound emitted from behind the sound emitting surface of the speaker in the internal space. A second sound emission path that propagates from the gap of the keyboard to the outside of the housing via is formed,
In the internal space in which the second sound emission path is formed , a control point is located at the antinode of the sound pressure of the natural vibration state of the specific frequency generated in the internal space by driving the speaker, and resonates at the specific frequency. A resonance body for reducing the sound pressure at the antinodes of the sound pressure of the natural vibration state is provided, and the resonance body is provided with an adjustment mechanism for adjusting a frequency at which the resonance frequency is resonated. Electronic keyboard instrument to play.

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