JP2007028085A - Array speaker system and line array unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an array speaker system the directivity controllable frequency band of which can optionally be designed in response to a required frequency band. <P>SOLUTION: A plurality of speaker sets 1A to D are connected. The connected position of the speaker sets can be detected. An audio signal is given to one of master speaker sets. The master speaker set supplies an audio signal to the other speaker sets 1 synchronously with the other speaker sets 1. Further, a delay amount of speaker units 11 of each speaker set 1 is controlled. With respect to the single speaker set, the apparent width of the array speaker system is twice and the interval of the speaker units is a multiple of 1/3. Thus, the frequency band wherein directivity control can be attained is enhanced. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to an array speaker system capable of directivity control, and more particularly to an array speaker system having an improved frequency controllable frequency band.

  In recent years, home theaters that can enjoy the presence of a movie theater at home have become widespread. In the home theater, as represented by 5.1 channel surround, it is common to install a plurality of speakers so as to surround the listener. However, the surround system realized by such a plurality of speaker devices has a problem that wiring to each speaker device becomes complicated and a space for installing the plurality of speaker devices is required.

  In view of this, there has been proposed an audio reproducing apparatus that uses a speaker array in which a plurality of speaker units are arranged in a line, and creates a virtual sound source around the listener using the sound beam of the speaker array and reflection from the wall of the room (for example, Patent Document 1).

  FIG. 7 shows the structure of a line array speaker in the audio reproduction apparatus described in Patent Document 1. This line array speaker is configured by arranging a plurality of speaker units 21 (21-1 to 21-n) on a line in an elongated casing. The speaker units 21 are arranged equidistantly at an interval d, and the width of the speaker array is L.

  When audio signals having the same phase are input to the plurality of speaker units 21, the synthesized wavefront of the audio output from all the speaker units 21 becomes an audio beam that is parallel and propagates only forward. The sound component propagating in a direction other than the front is canceled by combining the components output from the respective speaker units 21 (by interfering with each other), and only the component toward the front is strengthened by the combination to be a sound beam. Remain. Further, when the sound output from the speaker unit 21 is sequentially delayed from one end to the other end, the combined wavefront is inclined according to the delay time, and the sound beam can be directed obliquely.

As described above, by controlling the delay amount of the audio signals input to the plurality of speaker units, it is possible to direct the audio beam in the target direction (control the directivity).
JP-A-2005-64746

  In the line array speaker as shown in FIG. 7, when the width L of the speaker array is increased (the number of speaker units is increased), the directivity becomes sharper, and the sound beam can be concentrated in the target direction. Further, when the width L of the speaker array is increased, the directivity control can be performed to the lower frequency band side.

  The beam width of the sound beam is determined by Equation 1 below (where v is the speed of sound and f is the frequency).

θ = sin ⁻¹ (v / fdn) Equation 1
In order to increase the width L of the speaker array, the number of speaker units may be increased, or the distance d between the speaker units may be increased to implement the same number. However, if the distance d between the speaker units is increased, a problem arises in that another sound beam is generated in addition to the target direction due to the spatial folding phenomenon, which makes it difficult to control the directivity in the high frequency band. In order not to generate another sound beam, it is necessary to set d so as to satisfy the condition of Equation 2 below.

d <v / 2f Equation 2
For example, the low frequency side of the frequency band where the directivity can be controlled when the distance d between the speaker units is d = 4.5 cm and the width L of the speaker array is 67.5 cm is about 500 Hz from Equation 1, and the high frequency is The side is about 4 kHz from Equation 2. Therefore, the frequency band in which the directivity can be controlled is about 500 to about 4 kHz, and a band reproduction similar to a telephone voice can be performed, but the band reproduction required for home theater (for example, about 250 Hz to 12 kHz) cannot be realized. It was. In order to realize this, the number of speaker units must be increased, but there is a problem that the cost increases when the number of speaker units is increased.

  As described above, there is a trade-off between improving the directivity controllable frequency and suppressing the cost.

  An object of the present invention is to provide an array speaker system capable of arbitrarily designing a directivity controllable frequency band according to a required frequency band.

  In the array speaker system of the present invention, a plurality of line array units in which a plurality of speaker units are arranged on a straight line are connected in a vertical direction that is perpendicular to the straight line or in a horizontal direction that is the direction of the straight line. It is characterized by.

  In the present invention, the line array units are connected vertically or horizontally. For example, when two speaker arrays are arranged in parallel on the left and right, the apparent width L of the speaker array is doubled, and the lower limit frequency at which directivity control is possible is doubled.

  The present invention is further characterized in that the plurality of line array units arranged in the vertical direction are connected to each other by being shifted to the left and right by “the interval between the speaker units / the number of arrangement stages”.

  In the present invention, when n number of line array units are provided in the vertical direction, the line array units are provided by being shifted by 1 / n of the interval between the speaker units. If they are shifted and overlapped by 1 / n of the speaker unit interval, the apparent speaker interval d becomes 1 / n times, and the upper limit frequency at which directivity control is possible becomes n times.

  The present invention is further characterized in that a plurality of line array units are connected in the left-right direction, and another line array unit is connected vertically in the central portion of the arrangement in the left-right direction.

  In the present invention, line array units are connected in parallel on the left and right, and another line array unit is overlapped at the center. The direction controllable band on the low frequency side is improved by increasing the width of the speaker array, and the interval between the speaker units is not affected, so there is no need to connect separate line array units on the left and right ends of the line array unit. .

  The line array unit according to the present invention is a line array unit used in the array speaker system according to any one of claims 1 to 3, wherein a plurality of speaker units arranged in a straight line, an input unit for inputting an audio signal, The audio signal is supplied to each speaker unit with a predetermined delay, signal processing means for controlling the directivity of the line array unit, connection detection means for detecting the connection form and position therein, Control means for setting a delay amount of the signal processing means in accordance with the connection form detected by the connection detection means and the connection position.

  In this invention, a connection form and the position in it are detected, and the delay amount of each speaker unit is set according to the position. Thereby, the directivity is controlled in the entire array speaker system. Each control unit may set the delay amount independently, or any one of the connected line array units may set the delay amount of the entire array speaker system. Good.

  According to the present invention, it is possible to connect a plurality of line array units and change the apparent width of the speaker array and the interval between the speaker units. Bands can be designed arbitrarily.

  FIG. 1 is a schematic diagram showing the configuration of an array speaker system according to an embodiment of the present invention. As shown in the figure, this array speaker system includes a plurality of speaker devices 1A to 1D.

  The speaker device 1A and the speaker device 1B are connected side by side in the left-right direction. The speaker device 1C is connected above the speaker device 1A and the speaker device 1B, and the speaker device 1D is connected below the speaker device 1A and the speaker device 1B.

  Each speaker device 1 has a configuration in which eight speaker units 11-1 to 11-8 are arranged at equal intervals in a line at intervals d, and corresponds to a line array unit of the present invention. As the speaker unit, a cone type speaker unit is generally used, but other types such as a horn type speaker unit may be used. The distance from the speaker unit 11-1 at one end to the speaker unit 11-8 at the other end is L. This distance L is defined as the width L of the speaker device 1. Here, in the array speaker system of this embodiment, the speaker device 1A and the speaker device 1B are connected side by side in the left-right direction, so the apparent width of the array speaker system is 2L. In this example, a speaker device in which eight speaker units are arranged is shown, but a plurality of speaker units may be arranged or may be reduced.

  The speaker device 1C is connected to the upper center of the speaker device 1A and the speaker device 1B so that the horizontal position of the speaker is shifted to the right by d / 3. The speaker device 1D is connected to the lower center of the speaker device 1A and the speaker device 1B so that the horizontal position of the speaker is shifted to the left by d / 3. FIG. 2 is a diagram for explaining overlapping of the speaker device. As shown in the figure, the speaker device 1C is placed above the speaker device 1A and the speaker device 1B so as to be shifted to the right by a distance d / 3. Similarly, the speaker device 1D is placed below the speaker device 1A (and the speaker device 1B) so as to be shifted leftward by a distance d / 3. Therefore, the apparent distance between the speaker units of the array speaker system is the distance d / 3 for the overlapping portions.

  Here, the principle of the speaker array will be described. FIG. 3 is a diagram for explaining the principle of the speaker array.

  FIG. 2A shows a case where audio signals having the same phase are input to all speaker units 11 at the same time. When audio signals having the same phase are simultaneously input to all the speaker units 11, the sound output from the individual speaker units 11 propagates radially (circular), but the sound output from all the speaker units 11 is synthesized. As shown in the figure, the wavefront is narrowed down into a beam and propagates only forward. The components propagating in the other directions are canceled out by synthesizing (interfering with each other) the audio components output from the respective speaker units 11, and only the components directed forward are strengthened by the synthesis to form an audio beam. Remaining.

  FIG. 5B shows a case where the sound beam is formed obliquely. In the figure, the sound beam is formed at an angle of θ in the right direction from the front. In this case, sound is first output from the speaker unit 11 at the end (left end) opposite to the direction of the sound beam. Subsequently, every time τ elapses, sound is sequentially output from the speaker unit 11 on the right side. This delay time is controlled by a directivity control unit (described later) connected to each speaker unit 11. Thus, by sequentially delaying the sound output from the speaker units 11 arranged in a row from one end to the other end, the synthesized wavefront is inclined according to the delay time as shown in the figure, and the sound beam is Can be directed diagonally.

This inclination angle θ has a relationship of θ = sin ⁻¹ (vτ / d) where the speed of sound is v. Therefore, the angle θ of the sound beam can be controlled by controlling τ.

  FIG. 4 is a diagram showing an example of the sound beam control angle. In the graph shown in FIG. 6A, the horizontal axis represents θ, and the vertical axis represents the gain (G) of the speaker array. FIG. 6A shows the relationship between the angle θ and the gain G when the number of speaker units n = 16, the distance d between speaker units d = 4.5 cm, and the width L of the speaker array L = 67.5 cm as an example.

In FIG. 6A, θ = 0 is the target sound beam direction, and the gain G is maximum when θ = 0. As the distance from θ = 0 increases, the sound output from each speaker unit interferes and the gain G decreases, and becomes zero at θ = ± θ1. The width until the gain G becomes zero across the target sound beam direction θ = 0 is defined as the beam width. Θ1 at which the gain G becomes zero, that is, the width of the sound beam is determined by θ1 = sin ⁻¹ (v / fdn) from Equation 1 described above, where f is the frequency.

  FIG. 2A shows an example for the frequency f = 1 kHz. Here, in the present embodiment, since the speaker units are arranged equidistantly at an interval d, the width L of the speaker array is represented by L = d (n−1), and the beam width θ1 is expressed by Equation 1. Is determined by the distance d between the speaker units, the width L of the speaker array, and the frequency f.

  FIG. 6B is a diagram showing the relationship between the angle θ and the gain G when the number n of speaker units is four times n = 64 under the conditions in FIG. In the graph shown in FIG. 5B, the horizontal axis represents θ and the vertical axis represents gain. In FIG. 5B, the beam width is smaller than the beam width shown in FIG. 5A and has a sharp directivity in the target direction. Further, from the relationship of sin θ1 = v / fdn, the beam width as shown in FIG. 5B can be obtained even when the frequency f is quadrupled or the width d of the speaker unit is quadrupled.

  FIG. 10C is a diagram showing the relationship between the angle θ and the gain G when the frequency f is 1/4, f = 250 Hz, under the conditions shown in FIG. In the graph shown in FIG. 5C, the horizontal axis represents θ and the vertical axis represents gain. In FIG. 5C, there is no θ1 at which the gain G becomes zero.

  FIG. 4D is a diagram showing the relationship between the angle θ and the gain G when the frequency f is 8 times f = 8 kHz under the condition of FIG. Also in the graph shown in FIG. 4D, the horizontal axis represents θ and the vertical axis represents gain. In FIG. 4D, sound beams are also generated in directions other than θ = 0. This is called a so-called space folding phenomenon, and the phenomenon shown in FIG. 4D occurs at a frequency where d ≧ v / 2f.

  Thus, the speaker array has frequency dependency on the width of the sound beam. As in the above example, the number of speaker units n = 16, the distance d between speaker units d = 4.5 cm, and the width of the speaker array. In the case of L = 67.5 cm, the frequency band in which the directivity can be controlled is about 500 Hz to about 4 kHz. At a frequency lower than this frequency band, the directivity characteristics are lost as shown in FIG. 4C, and at a higher frequency, an audio beam is generated in a direction other than the target direction as shown in FIG. 4D.

  As described above, θ1 at which the gain G becomes zero is expressed by sin θ1 = v / fdn. Therefore, the influence of the frequency f, the distance d between speaker units, and the number n of speaker units on θ1 is equivalent. That is, by reducing the distance d between the speaker units and further increasing the number L of the speaker units to increase the width L of the speaker array, it is possible to widen the frequency bandwidth capable of directing control.

  Here, in the array speaker system of the present embodiment, the speaker device 1A and the speaker device 1B are arranged side by side in the left-right direction, so that the apparent number n of speaker units of this array speaker system is double, that is, the speaker array. , The frequency band in which the directivity can be controlled is doubled to the low frequency side. Further, since the speaker device 1C and the speaker device 1D are overlapped with each other by being shifted in the left-right direction by d / 3 in the vertical direction, the apparent distance between the speaker units of this array speaker system is d / 3, and directivity control is performed. The possible frequency band is expanded three times to the high frequency side.

  Therefore, in the array speaker system of the present invention, a single speaker device is designed in which the number of speaker units is reduced and the cost is reduced, and a plurality of speaker devices are provided as in the above example according to the required frequency band. By connecting these, it is possible to improve the frequency band in which directivity control can be easily performed.

  Next, the configuration of each speaker device of the array speaker system of this embodiment will be described in detail. FIG. 5 is a block diagram showing a configuration of each speaker device. As shown in the figure, the speaker device 1 includes n speaker units 11-1 to 11-n, a directivity control unit 12, a control unit 13, a clock switching unit 14, a connection detection unit 15, and a conversion unit 16. It has.

  The n speaker units 11-1 to 11-n are connected to the directivity control unit 12, and the directivity control unit 12 is connected to the control unit 13, the clock switching unit 14, and the conversion unit 16. In addition, a connection detection unit 15 is connected to the control unit 13.

  The directivity control unit 12, the control unit 13, and the clock switching unit 14 are connected to the directivity control unit 12, the control unit 13, and the clock switching unit 14 of other speaker devices 1, respectively. The directivity control unit 12, the control unit 13, and the clock switching unit 14 may be connected to other speaker devices 1 by sharing a single connection line (connection terminal), or each of them may be dedicated. You may make it connect with a connection line (connection terminal).

  The directivity control unit 12 supplies the input audio data to the speaker units 11-1 to 11-n with a predetermined delay amount to control the directivity of the speaker array. Each delay amount is set by the control unit 13. The speaker units 11-1 to 11-n respectively D / A convert the input audio data and emit sound.

  The control unit 13 controls the clock switching unit 14 and the directivity control unit 12 and transmits a control command to the control unit 13 of another connected speaker device 1 to control the other control unit 13.

  The clock switching unit 14 is connected to a crystal oscillator (not shown) built in the speaker device, and supplies a reference clock to the directivity control unit 12. The directivity control unit 12 operates based on this reference clock. When the clock switching unit 14 is connected to the clock switching unit 14 of another speaker device 1, the reference clock is transmitted to the clock switching unit 14 of the other speaker device 1. When a reference clock is received from another speaker device 1, either the reference clock received by the directivity control unit 12 or the reference clock of the built-in crystal oscillator is selectively supplied.

  The conversion unit 16 converts an analog audio signal input from an audio device into an A / D conversion function and, when digital audio data is input, a sampling frequency (for example, 44.1 kHz) of the audio data. And a frequency conversion function for converting to one reference frequency (for example, 48 kHz). The converted audio data is supplied to the directivity control unit 12.

  The directivity control unit 12 supplies the audio data input from the conversion unit 16 to the speaker units 11-1 to 11-n with a predetermined delay amount based on an instruction from the control unit 13, respectively.

  The connection detection unit 15 detects the connection state of each speaker device 1 and transmits to the control unit 13 at which position in the array speaker system the speaker device 1 is connected. As shown in FIG. 6, the connection detection unit 15 includes a plurality of connection terminals 15-s installed around the speaker device 1. Each speaker device 1 is provided with connecting terminals 15-s on the right side surface, the left side surface, the upper surface right side, the upper surface center right side, the upper surface center left side, the upper surface left side, the lower surface right side, the lower surface center right side, the lower surface center left side, and the lower surface left side. ing. The connection position can be detected depending on which connection terminal 15-s is connected to the connection terminal 15-s of another speaker device 1. For example, in the same figure, the speaker device 1A is connected to the right side terminal, the upper right terminal, the upper center right terminal, the lower right terminal, and the lower center right terminal. The connection detection unit 15 determines that the speaker device 1 is located on the left side of the middle stage in the array speaker system. Thereby, the connection position in the array speaker system can be detected. Note that these connecting terminals 15-s are installed at positions where the speaker unit 11 is connected to be shifted by d / 3 in the vertical direction as described above. In addition, the directivity control unit 12, the control unit 13, and the clock switching unit 14 described above are connected to the other directivity control unit 12, the control unit 13, and the clock switching unit 14 by the connection terminal 15-s. .

  In addition, the detection method of a connection position is not restricted to this example. For example, the user may specify the position of the speaker device 1 manually.

  Next, directivity control of this array speaker system will be described in detail. When a user connects an audio device to any one of the speaker devices 1 and inputs an audio signal, the speaker device 1 becomes a master speaker device of the array speaker system. This master speaker device controls other connected speaker devices 1. Note that the speaker device 1 to which an audio signal is input from an audio device may be a master speaker device, and another speaker device 1 may be a master speaker device. A speaker device to which an audio signal is directly input from an audio device may be automatically selected as a master speaker device, or may be manually selected by a user.

  The control unit 13 of the speaker device 1 that has become the master speaker device sets the clock switching unit 14 to read the reference clock from the built-in crystal oscillator. The directivity control unit 12 of the master speaker device operates with a reference clock supplied from the built-in crystal oscillator. In addition, the control unit 13 instructs the clock switching unit 14 to transmit the reference clock to the other speaker devices 1. The directivity control unit 12 of the other speaker device 1 operates based on a reference clock transmitted by the master speaker device.

  In the master speaker device, the digital audio data input from the conversion unit 16 to the directivity control unit 12 is transmitted to another speaker device 1. The directivity control unit 12 also operates by reading the reference clock from the clock switching unit 14 and supplies digital audio data to the other speaker devices 1. As a result, the digital audio data synchronized with all the speaker devices 1 is supplied. Note that an audio signal may be directly input from each audio device to each of the speaker devices 1, and then each directivity control unit 12 may synchronize audio data.

  The control unit 13 of the master speaker device sets the delay amount of the audio data supplied to each speaker unit 11 in the directivity control unit 12. Further, the controller 13 of all the connected speaker devices 1 is instructed to set the delay amount of the audio data supplied to each speaker unit 11 to the directivity control unit 12 of the speaker device 1. . Here, the master speaker device controls the directivity of the entire speaker unit as one speaker array. That is, in FIG. 1, audio data is supplied with a predetermined delay amount from the speaker unit 11-1 of the speaker device 1A to the speaker unit 11-8 of the speaker device 1B in order. At this time, the speaker device 1C and the speaker device 1D are assumed to be on the same line as the speaker device 1A and the speaker device 1B, and set their respective delay amounts. Thereby, the directivity characteristics of the entire array speaker system can be controlled.

  In the example described above, the delay amount of all the speaker devices connected to the master speaker device is set. However, each speaker device may set the delay amount independently. In this case, it is assumed that information defining the beam direction is transmitted and received between the speaker devices so that the sound beam is formed in the entire array speaker system.

  As described above, the array speaker system in the present embodiment connects a plurality of speaker devices 1A to 1D, synchronizes all the speaker devices, and detects the connection position. Since the apparent width of the array speaker system is doubled and the interval between the speaker units is 1/3, the frequency band in which the directivity control of the speaker unit can be controlled with respect to a single speaker device 1 is low. It will improve twice on the side and three times on the high frequency side.

  In the present embodiment, the array speaker system in which two in the left-right direction and three in the vertical direction are connected has been described. However, the present invention is not limited to this configuration example. Four stages may be connected in the vertical direction, or two stages may be connected. The speaker units may be placed with different widths depending on the number of the upper and lower parts. Since the number of speaker units to be connected is changed according to the frequency band that requires directivity control, it is possible to improve the frequency band in which directivity control can be easily performed while the speaker array has a reduced cost.

Schematic showing the configuration of the array speaker system The figure explaining the overlap of a speaker apparatus Diagram for explaining the principle of the speaker array Figure showing an example of the sound beam control angle Block diagram showing the configuration of the speaker device Schematic showing the connection terminal Block diagram showing a conventional line array speaker unit

Explanation of symbols

1-speaker device 11-speaker unit 12-directivity control unit 13-control unit 14-clock switching unit 15-connection detection unit 16-conversion unit

Claims (4)

  An array speaker system in which a plurality of line array units in which a plurality of speaker units are arranged on a straight line are connected in the vertical direction, which is a direction orthogonal to the straight line, or the horizontal direction, which is the direction of the straight line.   The array speaker system according to claim 1, wherein the plurality of line array units connected in the vertical direction are connected to each other while being shifted to the left and right by “the interval between the speaker units / the number of arrangement stages”.   The array speaker system according to claim 1 or 2, wherein a plurality of line array units are connected in the left-right direction, and another line array unit is connected in the vertical direction at a central portion of the arrangement in the left-right direction. A line array unit for use in the array speaker system according to claim 1,
A plurality of speaker units arranged in a straight line;
An input means for inputting an audio signal;
A signal processing means for supplying the audio signal to each speaker unit with a predetermined delay, and for controlling the directivity of the line array unit;
A connection detecting means for detecting a connection form and a position in the connection form;
Control means for setting a delay amount of the signal processing means according to the connection form and connection position detected by the connection detection means;
A line array unit comprising:

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