JP2006005747A - Ultrasonic radiator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ultrasonic radiator that can efficiently increase a sound pressure level at the time of emitting sound and has a wide reproduction frequency band and high productivity. <P>SOLUTION: This ultrasonic radiator is provided with magnetizing boards 13a and 13b with different magnetic poles alternately magnetized in a stripe shape, a flexible substrate 10 having a conductor pattern 11 to which signal current is fed and packing 12a and 12b where the conductor pattern 11 is arranged between parts magnetized in a stripe shape of the magnetizing boards 13a and 13b and a vibrating surface is divided by holding the vibrating surface of the flexible substrate 10 to form a plurality of ultrasonic vibrating surfaces. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasonic radiator used for a parametric speaker or the like that emits audible sound using ultrasonic waves as a carrier wave.

  2. Description of the Related Art An ultrasonic radiator used for a conventional parametric speaker is configured by developing a plurality, for example, several tens of ultrasonic transducers that vibrate due to a piezoelectric effect on a single printed board. Each ultrasonic vibrator constituting the ultrasonic radiator includes a vibration resonator, a resonance plate, a piezoelectric ceramic plate, and the like. A + electrode and a − electrode are formed on the front and back surfaces of the piezoelectric ceramic plate, and an electric signal is supplied to the + electrode and the − electrode to cause the piezoelectric ceramic plate to bend and vibrate. This mechanical vibration is transmitted to the vibration resonator bonded to the piezoelectric ceramic plate, and further vibrates the resonance plate bonded to the vibration resonator. The vibration resonator and the resonance plate to which the mechanical vibration of the piezoelectric ceramic plate is thus transmitted resonate at a specific frequency by vibrating each other, and generate ultrasonic waves (for example, see Patent Document 1). In such a vibration resonator and a resonance plate, an aluminum member is generally used so that resonance is sharply generated.

JP 2003-47085 A (Page 3, FIGS. 1 and 2)

  Since the conventional ultrasonic radiator is configured as described above, when a large number of resonant ultrasonic transducers are operated, the phase of the ultrasonic waves generated by each ultrasonic transducer becomes non-uniform, The sound pressure level does not increase as expected even when many vibrators are operated, and it is difficult to obtain a wide reproduction frequency band due to the resonance type. There was a problem that workability was poor and production cost was high.

  The present invention has been made to solve the above-described problems. An ultrasonic radiator that can efficiently increase the sound pressure level when emitting sound, has a wide reproduction frequency band, and has high productivity. The purpose is to obtain.

  The ultrasonic radiator according to the present invention is magnetized in the form of a magnet plate in which different magnetic poles are alternately magnetized in a stripe shape, a diaphragm having a conductor pattern to which a signal current is supplied, and a stripe shape of the magnet plate. And a holding member that divides the vibration surface to form a plurality of ultrasonic vibration surfaces by disposing a conductor pattern between the portions and holding the vibration surface of the diaphragm.

  According to the present invention, the conductor pattern of the diaphragm is arranged between the portions of the magnet plate that are magnetized in stripes, and the vibration surface of the diaphragm is divided to form a plurality of ultrasonic vibration surfaces. There is an effect that ultrasonic waves can be generated well.

An embodiment of the present invention will be described below.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a superdirective acoustic apparatus including an ultrasonic radiator according to Embodiment 1 of the present invention. The illustrated example is a configuration example of an apparatus that emits ultrasonic waves from a parametric speaker 4 and emits audible sound into a narrow space using a self-demodulation phenomenon that occurs when the ultrasonic waves propagate in the air. The superdirective acoustic apparatus shown in the figure is output from a sound source 1 that generates an audio signal, an acoustic radiation controller 2 that generates an ultrasonic signal by modulating the audio signal output from the sound source 1, and an acoustic emission controller 2. It comprises an amplifier 3 for amplifying an ultrasonic signal, and a parametric speaker 4 for generating an ultrasonic wave based on the ultrasonic signal output from the amplifier 3 and radiating it into the air. The acoustic emission controller 2 adds a carrier wave generation unit 5 that generates a signal indicating an ultrasonic wave to be used as a carrier wave, an audio signal input from the sound source 1 and a signal that indicates an ultrasonic wave generated by the carrier wave generation unit 5. An adder 6 for generating an ultrasonic signal is provided.

  FIG. 2 is a front view showing an overview of the ultrasonic radiator according to the first embodiment. This figure is a front view of the ultrasonic radiator 7 constituting the parametric speaker 4 shown in FIG. The same parts as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted. A plate 8 made of an iron plate or the like is provided in front of the ultrasonic radiator 7 illustrated in FIG. The plate 8 is provided with a plurality of radiation holes 9 for radiating ultrasonic waves generated inside the ultrasonic radiator 7 to the external space of the ultrasonic radiator 7.

  FIG. 3 is a sectional view of the ultrasonic radiator according to the first embodiment. This figure is a cross-sectional view of the portion indicated by a dashed line A-A ′ in FIG. 2 and shows the internal configuration of the ultrasonic radiator 7. The same parts as those shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. The ultrasonic radiator 7 is provided with a flexible substrate (vibrating plate) 10 made of, for example, a polyimide sheet member, as a vibrating member that vibrates by inputting an electric signal and generates ultrasonic waves. The flexible substrate 10 is a flexible printed substrate in which, for example, a conductor pattern 11 made of copper or aluminum is formed on the same layer on a thin polyimide sheet having a thickness of 50 μm, for example. The flexible substrate 10 is sandwiched on both sides of the vibration surface by packing (holding members) 12a and 12b made of a non-conductive member such as a resin formed in a lattice shape as shown in the figure. It is held so as not to cause slack in the inside. The packing 12a and the packing 12b coincide when the lattice-shaped portions are overlapped with the same shape and the same size. The flexible substrate 10 sandwiched between the packing 12a and the packing 12b is sandwiched between the same portions of the front and back, and one vibration surface is divided into a plurality of portions. That is, a plurality of ultrasonic diaphragms of a predetermined size partitioned by the packings 12a and 12b are provided.

  Inside the ultrasonic radiator 7, magnet plates 13 a and 13 b in which S poles and N poles are alternately magnetized in stripes are arranged on both sides of the flexible substrate 10. The magnet plates 13a and 13b are made of a hard member anisotropic plastic magnet plate or a soft member rubber type magnet plate, and a member suitable for the configuration of the ultrasonic radiator 7 is used. The magnet plate (first magnet plate) 13 a is arranged above the flexible substrate 10 in FIG. 3, that is, on the back side of the plate 8, and is connected to the radiation hole 9 provided in the plate 8. The through-hole which comprises is provided. The radiation hole 9 preferably has a diameter larger than the width of the conductor pattern 11 formed on the flexible substrate 10 so that the generated ultrasonic wave can be easily radiated to the outside. It is provided so that it may be located. The magnet plate (second magnet plate) 13b is disposed so that its surface faces the back surface of the flexible substrate 10 and is in contact with the bottom end of the packing 12b. A plate 14 made of, for example, an iron plate is disposed on the back side of the magnet plate 13b. The magnet plate 13a, packing 12a, flexible substrate 10, packing 12b, and magnet plate 13b disposed between the plate 8 and the plate 14 shown in FIG. The outer peripheral edges of the plate 8 and the plate 14 are fastened and fixed.

  FIG. 4A is a cross-sectional view of the ultrasonic radiator according to the first embodiment. What is shown is a cross-sectional view of the portion indicated by the one-dot broken line BB ′ shown in FIG. 3, the cross section of the packing 12 a or the packing 12 b, and the surface of the flexible substrate 10 held by the packing 12 a and the packing 12 b It is shown. The conductor pattern 11 formed on the flexible substrate 10 is bent so as to form a rectangle at each vibration surface (ultrasonic vibration surface) 15 divided by the packings 12a and 12b as shown in the drawing, and the rectangles are further connected. It is formed so as to go around all the vibration surfaces 15 of the flexible substrate 10. Each vibration surface 15 illustrated in FIG. 4A is configured by dividing the surface of the flexible substrate 10 with packings 12a and 12b so that a polyimide member having a thickness of 50 μm has a size of, for example, about 40 mm × about 30 mm. Is. The shape and size of the vibration surface 15 and the material and thickness of the flexible substrate 10 may be anything as long as they can vibrate in the ultrasonic frequency band, and are not limited to those described above.

  FIG. 4-2 is a cross-sectional view of another ultrasonic radiator according to the first embodiment. The flexible substrate 10 shown in FIG. 4A is divided into 16 vibration surfaces 15 by packings 12a and 12b. The number of vibrating surfaces 15 is provided so as to obtain a desired sound pressure. For example, when the signal current flowing through the conductor pattern 11 is large, for example, as shown in FIG. The shape of packing 12a, 12b is adjusted so that it may be formed, and the number of vibrating surfaces 15 is reduced as compared with that shown in FIG. 4-1. Conversely, when it is desired to obtain a large sound pressure, the number of vibrating surfaces 15 is increased.

  FIG. 5 is an explanatory diagram showing the configuration of the diaphragm of the ultrasonic radiator according to the first embodiment. The same reference numerals are used for the same parts as those shown in FIGS. This figure shows the vibration surface 15 shown in FIG. 4A and the magnetized portions 16 of the magnet plate 13a disposed on the front surface side of the vibration surface 15 and the magnet plate 13b disposed on the back surface side. It is. The magnetized portions 16 of the magnet plate 13a and the magnet plate 13b are obtained by alternately magnetizing the S poles and the N poles in a stripe shape as described above. As shown by the broken line in FIG. For example, when the ultrasonic radiator 7 is viewed from the front, the rectangular pattern of the conductor pattern 11 is arranged so as to sew between the magnetized portions 16. Preferably, the magnetized portion is magnetized so that the shape of the magnetized portion is parallel to the pattern extending in the longitudinal direction of the conductor pattern 11. Each magnetized portion 16 is provided so that a portion with a strong magnetic force does not overlap the conductor pattern 11, and in particular, the magnetized portion 16 of the magnet plate 13a is provided with the radiation hole 9 in the magnet plate 13a. The conductor pattern 11 is provided so as not to overlap with a pattern portion extending in the longitudinal direction. Further, the magnetized portion 16 of the magnet plate 13a and the magnetized portion 16 of the magnet plate 13b are arranged inside the ultrasonic radiator 7 with the same magnetic poles facing each other as shown in FIG. Each magnetized portion 16 is magnetized so as to have a magnetic force that causes the vibration surface 15 to vibrate in the ultrasonic frequency band in relation to the current value of the ultrasonic signal flowing through the conductor pattern 11. Specifically, for example, in the cross-sectional view of FIG. 3, the thickness of the portion magnetized to the S pole or N pole is increased or decreased, that is, the thickness of the magnet plates 13a and 13b is changed, and the ultrasonic wave is changed. Adjust so that the magnetic field required for generation is obtained.

Next, the operation will be described.
FIG. 6 is an explanatory diagram showing the operation of the ultrasonic radiator according to the first embodiment. The same parts as those shown in FIGS. 2 to 5 are denoted by the same reference numerals, and the description thereof is omitted. FIG. 6 shows a magnetic circuit formed around the vibration surface 15, and the magnetic circuit is indicated by a magnetic flux represented by a dashed-dotted arrow. As described above, the magnetized portions 16 of the magnet plate 13a are alternately magnetized to the N or S poles, and a magnetic field as shown in the figure is generated between the adjacent magnetized portions 16. As described above, since the magnet plates 13a and 13b and the flexible substrate 10 are arranged, the conductor pattern 11 of the flexible substrate 10 exists in this magnetic field. Since the magnetic flux in the space is directed from the N pole to the S pole, between the magnetized portion 16 magnetized at the S pole and the magnetized portion 16 magnetized at the N pole adjacent thereto, A magnetic circuit including the conductor pattern 11 disposed between the S pole magnetized portion 16 and the N pole magnetized portion 16 is formed. This magnetic circuit is formed above the flexible substrate 10 in the drawing, that is, in a space on the surface side of the flexible substrate 10. As described above, the magnetized portions 16 of the magnet plate 13b are also alternately magnetized to the N or S poles, respectively, and the dashed dotted arrows between the adjacent magnetized portions 16 in the magnet plate 13b. A magnetic field as shown by the magnetic flux is generated, and a magnetic circuit similar to that described above is formed in the space on the back side of the flexible substrate 10, that is, between the flexible substrate 10 and the magnet plate 13b.

  A current is passed through the conductor pattern 11 located in such a magnetic circuit, and the vibration surface 15 is displaced by the generated Lorentz force. Since the same current, that is, the same ultrasonic signal is supplied to the conductor pattern 11 of each vibration surface 15, all of the vibration surfaces 15 provided in the flexible substrate 10 vibrate in the same manner. Etc. Ultrasonic waves that are aligned are generated. Since each vibration surface 15 is separated by the non-transmission member packings 12a and 12b as described above, each vibration is not transmitted to the other vibration surfaces 15, and resonance or the like does not occur. As described above, since the ultrasonic waves having the same phase and the like are generated by the vibration surfaces 15, a sound pressure level proportional to the number of the vibration surfaces 15 can be obtained, and the ultrasonic waves can be generated efficiently. .

  As described above, according to the first embodiment, the flexible substrate 10 on which the conductor pattern 11 is formed as the vibration member, the lattice packings 12a and 12b that hold the flexible substrate 10, and the conductor pattern 11 are attached. Since the magnet plates 13a and 13b are magnetized, the flexible substrate 10 is divided into a plurality of vibration surfaces 15 by the packings 12a and 12b, and each vibration surface 15 in which the current of the ultrasonic signal is passed through the conductor pattern 11 is It is possible to vibrate in the same manner, and there is an effect that the sound pressure can be increased efficiently by generating ultrasonic waves by vibrations having the same phase and the like.

  In addition, since a plurality of vibration surfaces 15 are provided by holding a single flexible substrate 10 with lattice-shaped packings 12a and 12b, workability during manufacturing can be improved, and production costs can be reduced. There is an effect that can be done.

It is a block diagram which shows the structure of the super-directional sound apparatus provided with the ultrasonic radiator by Embodiment 1 of this invention. 1 is a front view showing an overview of an ultrasonic radiator according to Embodiment 1. FIG. 1 is a cross-sectional view of an ultrasonic radiator according to Embodiment 1. FIG. 1 is a cross-sectional view of an ultrasonic radiator according to Embodiment 1. FIG. FIG. 6 is a cross-sectional view of another ultrasonic radiator according to the first embodiment. FIG. 3 is an explanatory diagram illustrating a configuration of a diaphragm of the ultrasonic radiator according to the first embodiment. FIG. 5 is an explanatory diagram showing an operation of the ultrasonic radiator according to the first embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Sound source, 2 Acoustic radiation controller, 3 Amplifier, 4 Parametric speaker, 5 Carrier generation part, 6 Addition part, 7 Ultrasonic radiator, 8, 14 plate, 9 Radiation hole, 10 Flexible board (diaphragm), 11 Conductor Pattern, 12a, 12b Packing (holding member), 13a, 13b Magnet plate, 15 Vibration surface (ultrasonic vibration surface), 16 Magnetized part.

Claims (6)

A magnet plate in which different magnetic poles are alternately magnetized in stripes;
A diaphragm having a conductor pattern to which a signal current is supplied;
A holding member that forms the plurality of ultrasonic vibration surfaces by dividing the vibration surface by disposing the conductor pattern between the portions of the magnet plate magnetized in stripes and holding the vibration surface of the vibration plate And an ultrasonic radiator. The conductor pattern is formed by connecting a plurality of rectangles,
The ultrasonic radiator according to claim 1, wherein the holding member has the rectangular conductor pattern disposed so as to sew between the stripe-shaped magnetized portions. The magnet plate consists of first and second magnet plates magnetized in the same manner,
2. The ultrasonic radiator according to claim 1, wherein the diaphragm is disposed between the first magnet plate and the second magnet plate.   The ultrasonic radiator according to claim 3, wherein the first magnet plate is provided with a radiation hole for radiating ultrasonic waves generated by the diaphragm to the external space.   2. The ultrasonic radiator according to claim 1, wherein the holding member is a vibration absorbing member having a lattice shape that forms an ultrasonic vibration surface of about 40 mm × about 30 mm.   The ultrasonic radiator according to claim 1, wherein the diaphragm is made of a polyimide sheet having a thickness of 50 μm.

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