JP2005286584A - Parametric speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a parametric speaker having a remarkable change in an acoustic characteristic or an acoustic feeling. <P>SOLUTION: An electroacoustic transducer 100 performs acoustic radiation on the basis of a driving signal from a driving signal generating means 200. The transducer 100 is provided with an annular sound emitter 101 formed in a ring, and a circular sound emitter 102 positioned inside the emitter 101 and disposed concentrically with the emitter 101. At least either of the emitters 101 and 102 is configured so that its area is variable, and a directional angle as the electroacoustic transducer 100 can be controlled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a parametric speaker that radiates audible sound in a directional manner.

  Conventionally, as a directional sound source, a parametric speaker that obtains an audible sound by using a nonlinear phenomenon of air is known. As such a parametric speaker, for example, the sound source unit is composed of a plurality of ultrasonic transducers arranged in a multilayered annular shape, and the directivity as the parametric speaker is improved by changing the substantial diameter of the sound source unit. There was what was made to control (for example, refer to patent documents 1).

Japanese Utility Model Publication No. 4-103091

  The conventional parametric speaker controls the directivity by changing the diameter of the sound source section as described above. That is, the directivity is controlled by changing the outer shape of the circular sound source. However, in the configuration of the outer shape change by such a circular sound source, there is a problem that the directivity control range with respect to the diameter change is small.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to obtain a parametric speaker in which changes in acoustic characteristics or audibility are significant.

  The parametric speaker according to the present invention includes an electroacoustic transducer that radiates sound, and includes a ring-like sound generating portion having a variable area as a sound generating portion and formed in a ring shape.

  Since the parametric speaker according to the present invention includes a ring-like sound generating portion and the area of the sound generating portion is variable, a parametric speaker having a remarkable change in acoustic characteristics or audibility can be obtained.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a parametric speaker according to Embodiment 1 of the present invention.
In the figure, the parametric speaker includes an electroacoustic transducer 100, a drive signal generation unit 200, a control unit 300, and a distance detection unit 400.

  The electroacoustic transducer 100 is a sound source unit composed of a ring-shaped sound generating unit 101 formed in a ring shape and a circular sound generating unit 102 located inside the ring-shaped sound generating unit 101 and formed concentrically and circularly. Yes, the drive signal from the drive signal generation means 200 controlled by the control means 300 is supplied. The ring-like sound generation unit 101 and the circular sound generation unit 102 include, for example, a configuration in which ultrasonic transducers are arrayed, an electroacoustic conversion method having a film-type diaphragm such as a conductive type, a piezoelectric type, and an electrostatic type. And the area of the sound generating unit that emits acoustic radiation is variable. Details of the electroacoustic transducer 100 will be described later.

  The drive signal generation unit 200 includes an audio generator 201, an amplitude modulator 202, an amplifier 203, and a high frequency generator 204. The sound generator 201 is a functional unit that generates an audible sound. The amplitude modulator 202 is a functional unit that performs amplitude modulation by multiplying by an ultrasonic carrier signal for generating an ultrasonic wave from the high-frequency generator 204. The amplifier 203 is an amplifier for amplifying the modulation signal output from the amplitude modulator 202. The high frequency generator 204 is a functional unit for generating a high frequency ultrasonic carrier signal for use as a parametric speaker.

  The control means 300 includes a switch 301 and a controller 302. The switch 301 is a switch controlled by the controller 302, and selectively supplies the drive signal output from the drive signal generation means 200 to the ring-like sound generation unit 101 and the circular sound generation unit 102 of the electroacoustic transducer 100. It has a function. The controller 302 controls the switching of the switch 301 based on the distance detection signal detected by the distance detection unit 400, and also controls the area of the sounding part in the ring sounding part 101 and the circular sounding part 102. It is.

  The distance detection means 400 is a means having a configuration such as a known distance detection sensor that detects the listening position of the listener or an input unit that manually inputs the distance.

Next, details of the electroacoustic transducer 100 will be described.
The acoustic characteristic of the audible sound obtained by the parametric speaker shows the following tendency. The sound pressure level at a certain listening point is almost proportional to the area of the sound generation part, as in the conventional speaker. This means that, for example, if the area is doubled and halved, the changes are 6 dB and −6 dB, respectively. With regard to directivity, the circular electroacoustic transducer with the entire surface serving as a sounding part as in the past has little dependency on the aperture, and the change becomes larger by changing the structure of the sounding part in a ring shape, etc. Depends on the distance from the sound source.

FIG. 2 is an explanatory diagram illustrating a driving state of the electroacoustic transducer 100.
In the figure, (a) shows that only the ring-shaped sound generation unit 101 is driven out of the electroacoustic transducer 100 in which the circular sound generation unit 102 is concentrically arranged inside the ring-shaped sound generation unit 101. The state where it is not driven is shown, and (b) shows the state where both the ring-like sounding part 101 and the circular sounding part 102 are driven.

FIG. 3 is a characteristic diagram of the directivity angle of the electroacoustic transducer 100.
This characteristic diagram shows the relationship between the half-full angle (hereinafter referred to as the directivity angle) with respect to the total area of the sounding portions in the states of FIGS. In the figure, a characteristic 103a is a characteristic when the inner diameter of the ring-like sounding part 101 is changed when only the ring-like sounding part 101 is driven (FIG. 2 (a)), and the listening position from the sound source is It is a thing when it is far (for example, 10 times or more of the outer diameter of the ring-shaped sounding portion 101). In FIG. 3, the horizontal axis represents the sound source area of the electroacoustic transducer 100 (the total area of the sounding portion being driven). The reason is that, as described above, the sound pressure level is substantially proportional to the sound source area and does not depend so much on the configuration of the sound source.

  Similarly to the characteristic 103a, the characteristic 103b is a characteristic when the inner diameter of the ring-like sounding part 101 is changed when only the ring-like sounding part 101 is driven (FIG. 2A). When the listening position is near (for example, less than 10 times the outer diameter of the ring-like sound generation unit 101), the right ends of the characteristics 103a and 103b have an inner diameter of the ring-like sound generation unit 101 of 0, that is, This is a state of a circular sounding part whose entire surface is driven.

  On the other hand, the characteristics 104a and 104b are states when both the ring-like sound generation unit 101 and the circular sound generation unit 102 are driven (the state shown in FIG. 2B). These characteristics 104a and 104b are characteristics when the inner diameter of the ring-like sound generation unit 101 is constant and the diameter of the circular sound generation unit 102 is changed. When the characteristic 104a is far from the sound source, the characteristic 104b is the sound source. This is the case where the listening position from is close. Further, these characteristics 104a and 104b rise from the starting points 105a and 105b of the area of the ring-shaped sound generating portion 101 having a fixed inner diameter.

Next, the relationship between the operation and characteristics of the sound generation units 101 and 102 will be described.
By comparing the characteristics 103a and 103b of only the ring-like sound generation unit 101, it can be seen that the change in the directivity angle is small near the sound source and the change is large in the distance. From the distant characteristic 103a, there is an inflection point in the vicinity of a half of the sound source area (near the sound source area 350) with respect to the directivity angle (right end) in a circular state. 1. It can be seen that the angle changes by about 8 °. When the area of the sound source is halved, as described above, the change in sound pressure is reduced by 6 dB.

  Next, as shown in FIG. 2 (b), when the circular sound generating unit 102 is driven, the starting point 105a in which the area of the ring sound generating unit 101 is less than or equal to half of the circular sound generating unit having an inner diameter of 0. , 105b, when the circular sound generator 102 is inserted and driven, the directivity angle changes. In the case of the distant characteristic 104a, the change is large with respect to the characteristic 104b in the vicinity of the sound source, and the directivity angle changes approximately twice as much as the ring-like sound generation unit 101 alone, and the angle changes approximately 8 °. I understand that.

  Further, as a result of separately examining the relationship between the distance from the sound source (electroacoustic transducer 100) and the diameter of the sound source, the above-described large change in the directivity angle is 10 or more in the ratio of the distance to the outer diameter of the ring-shaped sound generation unit 101. It was found to happen in the state of.

  Based on such characteristics, in the present embodiment, as the characteristics of the electroacoustic transducer 100, the area of the ring-like sound generation unit 101 is the same as that of the entire sound generation part having an outer diameter equal to the outer diameter of the ring-like sound generation part 101. The distance to the target listener is 10 times or more of the outer diameter of the ring-shaped sound generation unit 101 and the total area as the sound generation unit is 2 times or more or 1 / The characteristic is controlled so that a change of 2 times or less occurs or a change of a half angle of 5 ° or more occurs.

  In addition, the total area of the sound generation unit is the sum of the areas of both the ring-like sound generation unit 101 and the circular sound generation unit 102. The configuration for changing the total area is that of the ring-like sound generation unit 101 or the circular sound generation unit 102. Either one area may be changed, or both areas may be changed.

  In the present embodiment, such data, that is, when only the ring-like sound generation unit 101 as shown in FIG. 3 is driven, or when both the ring-like sound generation unit 101 and the circular sound generation unit 102 are driven. It is assumed that the controller 302 holds data indicating the relationship between the sound source area and the directivity angle and the distance between the sound source and the listening position.

Next, the operation of the parametric speaker shown in FIG. 1 will be described.
First, the position of a listener (not shown) is detected by the distance detection unit 400 and input to the controller 302. On the other hand, the audio signal generated by the audio generator 201 is multiplied by the ultrasonic carrier signal from the high frequency generator 204 in the amplitude modulator 202. By this multiplication processing, amplitude modulation is performed and a modulated signal is obtained. The output signal of the amplitude modulator 202 is amplified by the amplifier 203 and input to the control means 300. The operation of these drive signal generation means 200 is the same as that of the prior art.

  The controller 302 controls the switch 301 based on the listener's position (distance between the electroacoustic transducer 100 and the listener) detected by the distance detector 400. That is, as described above, since the directivity angle data with respect to the sound source area as shown in FIG. 3 is stored in the controller 302, the controller 302 selectively controls the switch 301 based on a desired directivity angle or the like. . For example, selection control is performed such that the drive signal is supplied only to the ring-like sound generation unit 101 or the drive signal is supplied to both the ring-like sound generation unit 101 and the circular sound generation unit 102. Further, the area control of the ring-like sound generation unit 101 and the circular sound generation unit 102 is separately performed by the controller 302.

  In the above description, the driving conditions of the ring-like sound generation unit 101 and the circular sound generation unit 102 are based on the premise that they are driven by the same signal (in-phase). For example, an amplitude modulator 202 and an amplifier 203 are added, The drive signals from the two amplifiers 203 may be selectively supplied to the ring-like sound generation unit 101 and the circular sound generation unit 102, respectively. With such a configuration, for example, the two amplifiers 203 can have different frequency dependencies (characteristics that change the amplification factor depending on the frequency), and have different phases (for example, reverse phase, etc.). A configuration in which a signal is supplied to each of the ring-like sound generation unit 101 and the circular sound generation unit 102 may be added. And if it drives by another signal in this way, the change of directivity and a sound pressure level can be controlled largely.

  As described above, according to the first embodiment, in the parametric speaker that converts an audible sound into an ultrasonic wave, radiates acoustically from the electroacoustic transducer 100, forms a beam-like sound field, and reproduces it as an audible sound. Since the electroacoustic transducer 100 includes the ring-like sound generation unit 101 that has a variable area as a sound generation unit that performs acoustic radiation and is formed in a ring shape, the control range of the directivity angle can be increased, and as a result. Thus, it is possible to obtain a parametric speaker in which changes in acoustic characteristics or audibility are remarkable.

  Further, according to the first embodiment, electroacoustic conversion is performed in a parametric speaker that converts an audible sound into an ultrasonic wave, radiates acoustically from the electroacoustic transducer 100, and forms a beam-like sound field to reproduce the audible sound. The device 100 includes a ring-shaped sound generating portion 101 formed in a ring shape, and a circular sound generating portion 102 located inside the ring-shaped sound generating portion 101 and arranged concentrically with the ring-shaped sound generating portion 101. Since at least one of the sound generation units is configured to have a variable area as a sound generation unit that performs acoustic radiation, the control range of the directivity angle can be increased, and the ring sound generation unit 101 and the circular sound generation unit 102, it is possible to realize characteristics of different directivity angles with the same sound source area and characteristics of different sound source areas with the same directivity angle. It is possible to increase the selection of pressure levels.

  Further, according to the first embodiment, the electroacoustic transducer 100 has the ring-like sound generation unit 101 whose area is equal to or less than ½ of the area of the entire sound generation unit having an outer diameter equal to the outer diameter of the ring-like sound generation unit 101. In addition, the distance to the target listener is set to a position that is 10 times or more the outer diameter of the ring-shaped sound generating portion 101, and the total area as the sound generating portion changes by 2 times or more or 1/2 times or less. Since it is controlled so as to be generated, or to be controlled so that a change of a half-full angle of 5 ° or more occurs, the control range of the directivity angle with respect to the change of the sound pressure level can be increased.

Embodiment 2. FIG.
In the first embodiment, the example in which the electroacoustic transducer 100 is configured by the ring-shaped sound generation unit 101 and the circular sound generation unit 102 has been described. However, another sound generation is performed between the ring-shaped sound generation unit 101 and the circular sound generation unit 102. A portion may be arranged, which will be described below as a second embodiment.

FIG. 4 is an explanatory diagram illustrating the electroacoustic transducer 100a according to the second embodiment.
As illustrated, the electroacoustic transducer 100a according to the second embodiment includes an outer ring-shaped sound generation unit 101a, an inner ring-shaped sound generation unit 101b, and a circular sound generation unit 102. Here, the inner ring-shaped sound generation unit 101b is arranged between the outer ring-shaped sound generation unit 101a located at the outermost periphery and the circular sound generation unit 102 located at the center, and is an intermediate concentric with these sound generation units. It is a ring-shaped sounding part located in the part.

  For the electroacoustic transducer 100a configured as described above, drive signals are selected for the outer ring-shaped sound generation unit 101a, the inner ring-shaped sound generation unit 101b, and the circular sound generation unit 102, as in the configuration shown in FIG. A switch (not shown) for supply is provided, and these three types of sound generating units are selected and controlled by this switch. As this selection control, for example, control of driving only the inner ring-shaped sound generation unit 101b, driving of one of the outer ring-shaped sound generation unit 101a and the inner ring-shaped sound generation unit 101b and the circular sound generation unit 102, or all of them. Control such as driving of the sound generation unit can be performed.

  As a result, more detailed sound pressure level and directivity can be set. Also in the second embodiment, the same number of amplitude modulators and amplifiers as those corresponding to these three types of sound generation units are provided, and different signals such as frequency-dependent signals and anti-phase signals are provided for the respective sound generation units. A signal may be supplied. In this way, it is possible to set the sound pressure level and directivity in detail and to increase the control range.

  As described above, according to the second embodiment, the electroacoustic transducer 100a is configured by the outer ring-shaped sound generation unit 101a, the inner ring-shaped sound generation unit 101b, and the circular sound generation unit 102. The pressure level and directivity can be set.

  In the first and second embodiments, as the electroacoustic transducer 100 (100a), the ring-like sounding part 101 and the circular sounding part 102, or the outer ring-like sounding part 101a, the inner ring-like sounding part 101b and the circular sounding part. Although the configuration of 102 is used, the configuration may be such that only the ring-shaped sound generation unit 101 or the circular sound generation unit 102 such as only the outer ring-shaped sound generation unit 101a and the inner ring-shaped sound generation unit 101b does not exist. That is, the area of the ring-shaped sound generating portion is 1/2 or less of the area of the sound generating portion in a circular state, and the outer shape thereof is 1/10 or less of the distance to the listener, and is further driven in the ring shape. If the condition of the area is controlled so that the area of the sounding part changes more than double or 1/2 or less, or the half full angle changes more than 5 ° at the listener's position, only the ring-like sounding part The drive area may be controlled.

  Moreover, in the said Embodiment 1, 2, although the electroacoustic transducer 100 (100a) was circular (annular), it is not limited to this shape, It is polygonal, such as an ellipse, a rectangle, and a hexagon. There may be. In such a case, various polygonal shapes and the like can be considered in the same manner as circular shapes or circular shapes having the same area.

  Furthermore, in Embodiment 2 described above, two types of ring-like sound generating portions are used, but it may be divided into more ring-like sound generating portions.

It is a block diagram which shows the parametric speaker by Embodiment 1 of this invention. It is explanatory drawing which shows the drive state of the electroacoustic transducer by Embodiment 1 of this invention. It is a characteristic figure of the directivity angle of the electroacoustic transducer by Embodiment 1 of this invention. It is explanatory drawing which shows the electroacoustic transducer by Embodiment 2 of this invention.

Explanation of symbols

  100, 100a Electroacoustic transducer, 101 ring-shaped sound generation unit, 101a outer ring-shaped sound generation unit, 101b inner ring-shaped sound generation unit, 102 circular sound generation unit, 200 drive signal generation means, 300 control means, 400 distance detection means.

Claims (4)

In a parametric speaker that converts audible sound into ultrasonic waves and radiates sound from an electroacoustic transducer, forms a beam-like sound field and reproduces it as audible sound,
The electroacoustic transducer includes a ring-like sound generating portion having a variable area as a sound generating portion that performs the acoustic radiation and formed in a ring shape. In a parametric speaker that converts audible sound into ultrasonic waves and radiates sound from an electroacoustic transducer, forms a beam-like sound field and reproduces it as audible sound,
The electroacoustic transducer includes a ring-shaped sound generating portion formed in a ring shape, and a circular sound generating portion located inside the ring-shaped sound generating portion and disposed concentrically with the ring-shaped sound generating portion. A parametric speaker in which at least one of the sound generation units is configured to have a variable area as a sound generation unit that performs the acoustic radiation.   The electroacoustic transducer has a ring-like sound generating area whose area is equal to or less than ½ of the area of the entire sound generating part having an outer diameter equal to the outer diameter of the ring-shaped sound generating part, and the distance to the target listener The position of the ring-shaped sound generating portion is 10 times or more of the outer diameter of the ring-shaped sound generating portion, and the total area of the sound generating portion is controlled so as to cause a change of 2 times or more or 1/2 times or less. The parametric speaker according to claim 1 or 2.   The electroacoustic transducer has a ring-like sound generating area whose area is equal to or less than ½ of the area of the entire sound generating part having an outer diameter equal to the outer diameter of the ring-shaped sound generating part, and the distance to the target listener And the total area of the sound generating portion is controlled so that a change of a half-full angle of 5 ° or more occurs at the position of the listener. The parametric speaker according to claim 1 or 2.

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