JP2002199484

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DESCRIPTION JP2002199484
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to line
array loudspeakers and portable loudspeakers for performers and speakers or other events using
acoustic amplification.
[0002]
2. Description of the Related Art Line array loudspeakers are straight loudspeakers with a narrow
emission plane and radiating generally in a direction perpendicular to the line. Line speakers are
outlined on pages 35 to 36 of Acoustical Engineering (1991 edition) by Harry F. Olsen.
[0003]
One feature of line array loudspeakers is that in the near field, the decrease in intensity of the
sound energy is less rapid than that of a point source. The intensity of the sound energy of the
point sound source decreases by about 1 / r2. Where r is the distance from the point source to
the listening position. In the near field, the sound energy intensity from the line array
loudspeakers is less abrupt and theoretically reduces to 1 / r. Actual line array loudspeaker
implementations are often individual acoustic drivers arranged in a row.
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[0004]
SUMMARY OF THE INVENTION An important object of the present invention is to provide an
improved line array loudspeaker. Another important object of the present invention is to provide
an improved loudspeaker system for a player.
[0005]
SUMMARY OF THE INVENTION In one aspect of the present invention, a loudspeaker system
comprises a first loudspeaker array. The first array comprises an enclosure having a width and a
height and having at least six acoustic drivers, each acoustic driver having a radiating surface
and having a diameter less than 3 inches (7.62 cm). The at least six drivers are disposed at
substantially regular intervals on the first generally straight line of the enclosure such that the
edge separation of the radiating surface is less than 2 inches (5.08 cm). The first array is
configured and arranged to emit sound at a predetermined frequency range.
[0006]
In another aspect of the present invention, a loudspeaker system comprises a portable enclosure
and a first portable array module having at least six acoustic drivers disposed substantially
rectilinearly in the enclosure. The loudspeaker system also includes a second portable array and
a second portable array having a plurality of acoustic drivers arranged substantially linearly, and
a second portable array extending the first array substantially linearly. And a mounting system
for mounting to the array.
[0007]
In another aspect of the invention, a loudspeaker array module comprises a portable enclosure
having a mounting system for mounting the module to a second module. The loudspeaker array
module comprises at least six acoustic drivers. Each driver has a radiating surface and has a
diameter of less than 3 inches (7.62 cm), such that at least six drivers have an edge spacing of
less than 1 inch (2.54 cm) The enclosures are arranged at regular intervals on a substantially
straight line. The loudspeaker array module is constructed and arranged to emit sound
essentially over the full range of the audio frequency spectrum.
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[0008]
According to another aspect of the invention, a method of improving the power converted per
unit radiation area of a line array loudspeaker array comprises radiation having edges less than 3
inches (7.62 cm) in diameter, respectively. Attaching the plurality of acoustic drivers comprising
the surface on a substantially straight line and placing the acoustic drivers on the lines such that
the separation of the edges of the radiating surface of the adjacent acoustic driver is not greater
than 1 inch (2.54 cm) And.
[0009]
A loudspeaker system for live sound source includes a line array loudspeaker comprising a line
array of a plurality of acoustic drivers.
Each driver has a diameter of less than 3 inches (7.62 cm). The plurality of drivers are arranged
in the enclosure in a substantially straight line at regular intervals less than 1 inch (2.54 cm), and
the line array is constructed and arranged to be arranged facing the audience near the live sound
source .
[0010]
In yet another aspect of the invention, a loudspeaker system for public facilities having a floor
and having a listening area with an intended listening height range above the floor comprises an
upper and a lower part and an upper part And a line loudspeaker array comprising a plurality of
acoustic driver arrays on a generally straight line joining the lower part, the upper and lower
parts defining a plane perpendicular to the line. The array is sized and positioned so that the
lower portion is substantially near the floor, such that the intended listening height is between
the plane defined by the upper portion and the plane defined by the lower portion.
[0011]
Other features, objects, and advantages will be apparent from reading the following detailed
description with reference to the accompanying drawings.
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[0012]
DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, and in particular to
FIG. 1, the loudspeaker system of the present invention is shown.
The line array loudspeaker system 10 comprises a line array loudspeaker module 12. The line
array loudspeaker module 12 comprises a large number (smaller than 3 inches in diameter, or a
wavelength of about 5 KHz sound) of an acoustic driver 14, preferably an acoustic such as a cone
driver having a broad emission surface for the full width of the driver Have a driver. The driver is
usually round but may be an oval or "race track" driver smaller than 3 inches in diameter. The
acoustic drivers 12 are arranged on a straight line which may be substantially straight even
when viewed from the front and the side. The acoustic drivers are closely spaced (i.e. mounted so
that the edges of the emitting surface are close to one another and the non-emitting part of the
line array loudspeaker module is small). Line array loudspeaker module 12 is surrounded by
enclosure 13. The front of the line array loudspeaker module 12 can be covered with an
acoustically transparent cover such as a cloth or mesh (not shown in this figure) to protect the
acoustic driver 14.
[0013]
In one embodiment, the line array loudspeaker module 12 is mounted from Bose Corporation of
Framingham, Mass., With a center-to-center distance of about 3 inches, such that the gap
between the edges of the radiation cone is about 0.75 inches. It includes 12 commercially
available 2.5 inch diameter cone acoustic drivers. The enclosure 13 is a closed back structure
having a height h of about 36 inches, a width w of 3 inches, and a depth d of 4 inches. The aspect
ratio (ratio of height to width) of the module is 12: 1. In a typical line array system comprising
multiple line array modules, the aspect ratio is 24: 1 or 36: 1. The line array module 12 weighs
approximately 19 pounds (8.62 kg) for easy portability. The line array is flat at the bottom so
that it can be placed on the floor or easily attached to a fixed stand (not shown). The line array is
constructed and arranged for an operating range of about 7 octaves, for example about 120 Hz
to 15 kHz.
[0014]
The 2.5 inch diameter of each acoustic driver is equivalent to the wavelength of a sound wave
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having a frequency of about 5.4 kHz, which is about an octave below the highest frequency
designed for the loudspeaker system. Line array loudspeakers using smaller diameter acoustic
drivers maintain a smooth vertical distribution at high frequencies and a gradual drop in sound
energy intensity. A further advantage of the line array loudspeaker according to the invention is
that the line array can convert relatively large amounts of electrical energy. In one embodiment,
a line array according to the present invention is capable of converting 7 watts of power per
square inch of the emitting surface to acoustic waves.
[0015]
Referring now to Figures 2a-2c, another embodiment of the present invention is shown. In this
embodiment, the enclosure 13 comprises a slot port 16 that connects the back (not shown) of the
acoustic driver 14 to the front of the enclosure 13. In FIG. 2 b, the acoustic drivers 14 are
individually enclosed, each individually enclosed driver having a port 16. Figure 2c shows a
cross-sectional view along the lines 2c-2c of Figures 2a and 2b.
[0016]
The sound energy intensity of the line array loudspeaker according to the invention drops less
rapidly than 1 / r2. Referring now to FIG. 3, there is shown a calculated graph of sound pressure
level (SPL) versus distance from the speaker. Curve 30 represents a typical compact loudspeaker
and curve 32 represents a line array loudspeaker according to the invention. The two speakers
were equalized and adjusted to have the same frequency response and the same SPL (90 dB) 2
meters (6 feet 8 inches) from the speakers, and the SPL was calculated at floor height. The effects
of floor reflections are included in both sources. At 60 feet from the speaker, it can be seen that
the SPL of the line array loudspeaker according to the invention is only about 10 dB down from
the SPL at 6 feet 8 inches. At 60 feet from the speaker, a typical compact loudspeaker is 6 feet 8
inches to 18 dB down. The closely spaced small drivers ensure that the line array loudspeaker
according to the invention continues to operate as a line array loudspeaker even at high
frequencies (as opposed to point source groups), even at high frequencies. Mostly emit sound
waves. Because the individual drivers are smaller, the line array loudspeakers according to the
invention have a wider horizontal dispersion than conventional line array loudspeakers,
especially at higher frequencies. Also, it can be seen from FIG. 3 that there is an adequate sound
pressure level (about 76 dB) at 100 feet while the sound pressure level (about 90 dB) is not
objectionable where the player stands. Furthermore, it can be seen from FIG. 3 that the sound
pressure level is about 96 dB even when the performer is very close to the speaker, while the
sound pressure level exceeds 100 dB when using the conventional compact speaker, Not only
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uncomfortable but also harmful. While six feet and eight inches may be a typical distance r1
from the line array loudspeaker system to the performer, 60 to 100 feet is a typical distance r2
from the speakers to the farthest audience sell.
[0017]
With reference to FIGS. 4-7, the structure of the loudspeaker system for live sound sources, such
as a music player, is shown. The line array loudspeaker system 10 can be placed behind the
performer 22 and facing the audience in the listening area 11. Because the line source array
tends to have minimal vertical dispersion, the sound energy intensity above the top of the
speaker is significantly lower than the sound energy intensity below the top of the speaker. To
ensure that all parts of the audience get proper sound, the top of the portable line array
loudspeaker according to the invention is about the same height as the performer's head or the
head of the audience 24 whichever is higher , The height h of the line array loudspeaker system
10 can be changed. For convenience, the range of height including the head of the performer and
the head of the audience is referred to as the "intended listening height range".
[0018]
FIG. 5 shows the situation where the floor is "rake", ie, the floor is not a single horizontal plane,
but an inclined plane or a series of stepped planes or steps. In FIG. 5, the height h is sized such
that the intended listening height range is between two planes perpendicular to the line array
loudspeaker, and one of the two planes (through line 13 Including and perpendicular to the
plane of the drawing) is defined by the top of the line array loudspeaker, the other (including the
line 15 and perpendicular to the plane of the drawing) is defined by the bottom of the line array
loudspeaker .
[0019]
FIG. 6 shows that the floor is inclined at an inclination angle θ (if the floor is flat, the inclination
angle is the angle of the floor to the horizontal, but if the floor is a series of horizontal planes or
steps, the inclination angle is Fig. 9 illustrates another configuration with a sloping floor), which
is the angle with respect to the horizontal of a line connecting common points such as the front
edge of the. In FIG. 6, the line source is inclined such that the two planes are inclined with
respect to the horizontal, since the main axis of the line source is perpendicular to the inclination
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angle θ. In the configuration of FIG. 6, the line array should be sized such that the height h of
the line array is somewhat longer than the intended listening height range. If the line connecting
the common points is not a straight line, the angle at which the line array is tilted and the height
of the line array are set so that the intended listening height range is between the two planes
perpendicular to the line array loudspeaker , One of the two planes (including the through line
13 and perpendicular to the plane of the drawing) is defined by the top of the line array
loudspeaker, the other (including the through line 15 and perpendicular to the plane of the
drawing) is , Defined by the bottom of the line array loudspeaker. In the configuration of FIG. 6,
the height h of the line array need not be as long as the configuration of FIG. FIG. 7 shows an
alternative arrangement in which the performer group includes two performers 22a and 22b,
each performer having line arrays 10a and 10b, respectively, arranged close (in this case,
behind).
[0020]
The arrangements of FIGS. 4-7 are particularly advantageous. According to the sound system of
the present invention, the player hears substantially the same sound as the sound heard by the
audience. Furthermore, because it is possible to place the line array loudspeakers behind the
performer, it does not interrupt the view of the performer of the audience, which means that the
line array loudspeakers are very narrow and more for the audience It is an advantage that is
enhanced by having a large height-to-width aspect ratio, which means less noticeable. Also,
because the sound field is substantially uniform, there is only a slight possibility of feedback
through the microphone 26.
[0021]
The small size, portability, modularity (discussed below), resistance to feedback through
microphones, and low cost due to simple electronics (discussed below) make the line array
according to the invention particularly attractive to a performance group. Each member of the
group can place a line array in the vicinity of his / her own (usually behind or behind the
performer). This arrangement eliminates the need for expensive mixing circuits, the need for
people to adjust the mixing circuits, and the need for so-called "backline" loudspeakers.
Furthermore, this arrangement makes the arrangement more pleasing to the audience, as the
sound from each performer sounds as coming from near the performer rather than from a
common loudspeaker system that may be away from one of the performers A stick
psychoacoustic effect is provided.
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[0022]
The small size, portability, modularity, resistance to feedback, and low cost also allow the line
array according to the invention to be used especially in public places, eg microphones attached
for speakers or pre-recorded It is attractive for use as a portable sound system as a loudspeaker
with an audio signal source for playing back messages and music.
[0023]
The line array according to the invention can also be used in public halls, meeting rooms, places
of worship, halls, and similar spaces in a permanently mounted arrangement.
The line array according to the present invention can be oriented with the lines vertically and be
of appropriate length such that the audience and the player's head is between the horizontal
planes defined by the top and bottom of the line array. Such a line array is advantageous because
the line array according to the invention can be unobtrusive, easier to integrate into a building,
and can be relatively easy to access for installation, maintenance . The relative distance between
the line array and the performer, and the line array and the spectator, is very flexible as the
decrease in sound energy intensity is gradual and the possibility of feedback through the
microphone is low.
[0024]
Referring now to FIG. 8, the electronic circuitry of the system element is shown. The signal input
is coupled to the acoustic driver 14 by a signal amplifier 19. Since the acoustic drivers are
connected in parallel to the amplifier 19 and there is no filtering or shading circuit, all acoustic
drivers receive essentially the same signal at all frequencies. Although not shown in this figure,
there may be equalization circuits, which equalize all acoustic drivers the same so that the signals
received by all acoustic drivers are the same at all frequencies. Do. The circuit of FIG. 8 is
relatively inexpensive, uncomplicated, and allows the system according to the invention to be
implemented with relatively few amplifiers and other components. The present invention
provides a line array loudspeaker system 10 by providing an attachable line array loudspeaker
module to create a longer line array loudspeaker as described in the description of FIGS. 4 and 5.
Make extension easy. Furthermore, since the electroacoustic conversion is divided among many
acoustic drivers, the total amount of voice coil structure is divided by the number of acoustic
drivers, and the heat generating components are dispersed, so that the total amount of energy
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can be increased. It can be sent to the module.
[0025]
Referring to FIG. 9, a feature of the present invention for extending a line array loudspeaker is
shown. Each enclosure 13 of the line array module loudspeaker 12 is provided at the back with a
T-shaped channel 30 in which the flange 32 fits. The flange 32 is held in place by a set screw 34
which may be a thumb screw. The channel 30 may be provided with indentations, stops or holes
for receiving the push screw 34 for slip prevention. Channels 30 may extend the entire length of
enclosure 13 or may be only near the top and bottom of enclosure 13. The flange 30 is then held
in place by the second set screw 34, even if it fits into the channel 30 of another enclosure of
another line array module loudspeaker, whereby one line array module loudspeaker is Fixedly
mounted end to end on another line array module line loudspeaker, a two module long line array
loudspeaker can be created. Additional line array module loudspeakers can be similarly attached
at the end to create several modules long line array loudspeakers. Simple electrical connections
between signal sources and modules and between modules are possible due to the fact that in
addition to relatively simple mechanical connections, each module has the simple electrical
connection of FIG. 9 without filtering or shading circuitry become. Modularization allows
individual modules to be easily transported and to be assembled in the field. This feature makes
the line array loudspeaker according to the invention particularly attractive to a sound system for
music players.
[0026]
If desired, separate bass units can be associated with the line array loudspeakers to enhance the
bass energy emitted by the line array loudspeakers in applications requiring more bass energy.
The separate bass unit may be located at a distance from or near the line array loudspeakers, and
if placed in the vicinity, attached to the base of the line array loudspeakers and the line It can
help stabilize the array loudspeakers.
[0027]
It is self-evident that those skilled in the art can now make numerous modifications and
developments of the specific devices and techniques disclosed herein. As a result, the present
invention is intended to embrace each and every novel feature and novel combination of features
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presented or possessed by the devices and techniques disclosed herein, limited only by the spirit
and scope of the appended claims. It is interpreted as a thing.
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