JPH08111896A - Electroacoustic transducer - Google Patents

Abstract

PURPOSE: To perform acoustic generation like a natural musical instrument by utilizing the resonance vibration of a lower front board. CONSTITUTION: The output of an electronic piano is supplied through a lead wire 20 for electric signals to a voice coil 15. Thus; by audible frequency electric signals supplied to the coil 15 for forming one of electromagnetic drive units, attracting and repulsive force corresponding to the height of a frequency and the strength of the signals is generated between a yoke 18 and a pole piece 19 at the tip of a magnet 17 for forming the other electromagnetic drive unit. A magnet system composed of the magnet 17, the yoke 18 and the piece 19 is fixed to the supporter 14 of a back board 13 and is constituted as a moving- coil type. Thus, the attraction and repulsion generated between the electromagnetic units becomes driving force for vibrating the lower front board 12. By considering the characteristics of the lower front board 12 in this case, acoustic output similar to the output from a natural musical instrument is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroacoustic transducer for converting an electric signal into an acoustic signal in an electronic musical instrument, an audio device or the like.

[0002]

2. Description of the Related Art As shown in FIG. 3, a magnetic speaker that has been widely used in the past has a fixed magnet (permanent magnet) 1 and a voice coil 2 movably arranged in the magnetic field of the magnet 1. The cone (vibration body) 3 to which the voice coil 2 is attached is a main component.

In addition to the above-mentioned components, the conventional magnetic speaker has a yoke (yoke) as a magnetic path.
4, frame 5, pole piece 6, dust cap 8,
The center holder 9 and the like are provided.

In the magnetic speaker having such a structure, air is directly vibrated by the cone (vibrating body) 3 according to the strength and frequency of the audio current supplied to the voice coil 2 to perform electroacoustic conversion. There is.

In such a conventional speaker, air is forcibly oscillated in a piston movement manner, and therefore has the following features. 1) No distortion and flat faithful reproduction over the audible band, so that the vibrating body is in a non-divided integrated vibrating form, and air is driven by a piston. 2) Since the piston is driven by air, the vibrating body has a small area and is made of a light and strong material, and the periphery of the vibrating plate is given an appropriate stiffness by edge treatment.

On the other hand, the conventional speaker has the following problems. 1) Since the air resistance increases and a large driving force is required, it is difficult to increase the area of the vibrating body. 2) Normally, the area of the vibrating body is small and it becomes a point sound source, and it is not possible to feel the spread of surface sound source, which is important for musical instruments.

3) It is difficult for the vibrating body alone to faithfully reproduce over the entire audible band, and it becomes more difficult as the vibrating body area increases. Therefore, it is necessary to divide the speaker system into high-pitched sound regions, low-pitched sound regions, and the like such as woofers and squawkers depending on the band to cover the entire audible band. 4) The original sound of the musical instrument is a sound due to air resonance or a vibration body resonance, and has a different property from the sound due to a cone vibration body such as a speaker.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is different from a conventional piston vibrating electroacoustic transducer for air, such as a speaker, which is a natural instrument such as a piano or a harpsichord. It is an object of the present invention to provide an electroacoustic transducer capable of generating a sound like a natural musical instrument by approximating the vibration form of an acoustic resonance plate of a musical instrument.

[0009]

A housing for an electronic musical instrument such as an electronic piano, for example, a lower front plate (12) and a rear plate (13).
By attaching an electromagnetic drive unit consisting of a voice coil (15) and a magnet system (17, 18, 19) between the and, and utilizing the resonance vibration of the lower front plate (12), a natural musical instrument such as a piano or a harpsichord. It features an electro-acoustic transducer that gives the same acoustic output characteristics as the sounding board.

In this case, the voice coil (15) constituting the electromagnetic drive unit has a lower front plate (1) which generates vibration.
2) Can be attached to the side. On the contrary, the magnet system (17, 18, 19) can be attached to the back plate (13) side.

[0011]

According to the electroacoustic transducer of the present invention, sound is generated by the resonance vibration of the diaphragm. Therefore,
Even if the diaphragm area is increased, a large acoustic output can be obtained with a small driving force. Furthermore, it is possible to reproduce the sound over the entire audible band with the diaphragm alone.

Since the resonance vibration of the diaphragm in this case approximates the resonance sound output inherent to the musical instrument, it can be used as an acoustic system for electronic musical instruments and audio devices.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a sectional view showing a state in which an electroacoustic transducer according to the present invention is applied to a housing structure of an electronic piano which is a typical electronic musical instrument 11.

In the figure, 11 is an electronic musical instrument body, 12 is a lower front plate 12 (vibration plate), 13 is a back plate, 14 is a support column, and 1
5 is a voice coil, 16 is a fixture, 17 is a magnet, 18 is a yoke, 19 is a pole piece, 20
Is a lead wire for an electric signal.

In FIG. 1, the lower front plate 12 of the electronic musical instrument 11 is a vibrating plate, and the electromagnetic drive unit is made to function. A support 14 is attached to the back plate 13 of the electronic musical instrument 11.

A voice coil 15 is attached to the lower front plate 12 functioning as a diaphragm via an attachment 16.

A magnet system composed of a magnet 17, a yoke (yoke) 18 and a pole piece 19 is fixed to the column 14 attached to the back plate 13. The fixed position of the pole piece 19 is the portion located inside the voice coil 15, and is the tip of the magnet 17.

The pole piece 19 has a function of extending a magnetic pole and effectively exerting a magnetic action on the voice coil 15.

The output of the electronic piano is supplied to the voice coil 15 via the electric signal lead wire 20. As a result, the audio electric signal supplied to the voice coil 15 forming one of the electromagnetic drive units causes the frequency of the high and low frequencies to be increased between the pole piece 19 and the yoke 18 at the tip of the magnet 17 forming the other of the electromagnetic drive unit. Also, suction / repulsion force is generated according to the strength of the signal.

In the configuration of FIG. 1, the magnet system including the magnet 17, the yoke 18 and the pole piece 19 is fixed to the support 14 of the back plate 13 and is configured as a movable coil, so that the electromagnetic system is provided between the electromagnetic units. The generated suction / repulsion force is almost all driving force for vibrating the lower front plate 12 as a reaction force to the voice coil 15.

In this case, by considering the characteristics of the lower front plate 12, it is possible to obtain an acoustic output similar to that of a natural musical instrument. In addition, it is desirable that the lower front plate 12, the voice coil 15, and the mounting tool 16 that form the movable portion have a structure suitable for a sound generation source as a whole.

In the structure of such an electroacoustic transducer, the voice coil 15 is mounted at the lower front plate 1.
It has been confirmed that it is desirable from the viewpoint of the vibration mode to have a portion about 1/4 from the upper side of the length of the diagonal line from the second corner.

FIG. 2 shows another embodiment of the present invention, in which the movable portion and the fixed portion in the structure shown in FIG. 1 are mutually converted into a so-called movable magnet type. Since the respective constituent elements are in principle the same as those in the first embodiment described above, they are designated by the same reference numerals as those in FIG.

In this embodiment, the voice coil 15 is fixed to the column 14 provided on the back plate 13. The voice coil 15 in the embodiment of FIG. 1 is a vibration system (movable part).
However, it is necessary to consider the configuration, for example, the thickness of the winding wire, the material, the shape, the size, and the weight of the bobbin.

However, since the voice coil 15 is fixed in this embodiment, it is sufficient to consider the electromagnetic characteristics exclusively. Therefore, the degree of freedom in design is increased, for example, by increasing the thickness of the winding to enable generation of a large electromagnetic force by supplying a large current.

On the other hand, the lower front plate 12 has a magnet 17,
A magnet system including a yoke 18 and a pole piece 19 is attached.

Therefore, it is necessary to consider the mass of these magnet systems and the mounting means so that they are suitable for the vibration system. It should be noted that the attachment position of the magnet is preferably a portion corresponding to the attachment position of the voice coil in the above-described first embodiment.

[0028]

As described above, according to the electroacoustic transducer of the present invention, it is possible to employ a diaphragm having acoustic characteristics similar to those of a natural musical instrument. This diaphragm is part of the housing of the electronic musical instrument, and when applied to an electronic piano, the lower front plate itself is the diaphragm.

Therefore, the disadvantage of the frequency-dependent acoustic characteristic as in the conventional speaker system is eliminated, and an acoustic system close to a natural musical instrument can be constructed.

By considering the characteristics of the diaphragm, it is possible to cover the sound range generated by the musical instrument with a single diaphragm, so that high-pitched sound, middle-pitched sound, low-pitched sound, etc. are generated as in the case of sound generation by a conventional speaker system. A complex system that divides and covers each musical range is unnecessary, and great economic and technical advantages are obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a housing showing a configuration of a first embodiment in which an electroacoustic transducer according to the present invention is applied to an electronic piano which is a typical electronic musical instrument.

FIG. 2 is a sectional view of a main part of a housing showing a configuration of a second embodiment in which the electroacoustic transducer according to the present invention is applied to an electronic piano which is a typical electronic musical instrument.

FIG. 3 is a cross-sectional view showing a configuration example of a magnetic speaker which is an electroacoustic conversion system according to a conventional technique.

[Explanation of symbols]

 11 Electronic Musical Instrument 12 Lower Front Plate (Vibration Plate) 13 Back Plate 14 Struts 15 Voice Coil 16 Fixture 17 Magnet 18 Yoke (Yoke) 19 Pole Piece 20 Electrical Signal Lead Wire

Claims (3)

[Claims] 1. A natural musical instrument by mounting an electromagnetic drive unit composed of a voice coil and a magnet system between a lower front plate and a rear plate of an electronic musical instrument such as an electronic piano and utilizing resonance vibration of the lower front plate. An electroacoustic transducer characterized by imparting the same acoustic output characteristics as those of the sounding board. 2. The electroacoustic transducer according to claim 1, wherein a voice coil that constitutes the electromagnetic drive unit is attached to the lower front plate side that generates vibration. 3. The electroacoustic transducer according to claim 1, wherein a magnet system constituting the electromagnetic drive unit is attached to a back plate side.