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1. Title of Invention 2, Inventor's Address, Clarence Road, 11 Wayland, Mass., USA Name: Roy
Frederic Allison 6, Patent Assignee's Address, Nadeysk, Mass., USA, Titch Zakul 7 @ 50024947.
[Phase] Japan Patent Office ■ Japanese Patent Application Laid-Open No. 50-122E3250
Japanese Patent Application No. 50. (19'75), 9 ', 26 Japanese Patent Application No. 50-2.4-94-7
[Phase] Application date: O, 097, auxiliary document 64-6,555 specification 1, title of the
invention] 1, title of the invention] speaker system
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an audio speaker
system. It is well known that direct radiation speakers are extremely inefficient in converting
electrical energy into acoustic energy. For example, in the case of a commercially available direct
radiation type speaker system and a closed box having a volume of about 8 cubic feet or less
(about 1/9 cubic meter), its exchange efficiency is only lf +. Such low efficiency is due to the
occurrence of impedance mismatch because the resistance component of the radiation
impedance (load) is extremely small compared to the impedance of other electro-acoustic
circuits. Also, as is well known, the resistance component (radiation resistance) of the above
circuit is inversely proportional to the effective radiation angle expressed by steradians emitted
by the speaker. For this reason, the radiated acoustic output of the direct radiation speaker
system doubles when the effective radiation angle of the system is halved. If the speaker's
diaphragm can be mounted flush with the wall of the room (at a distance of 5) and at a certain
distance from the walls of both neighbors, the radiation angle is reduced from 4π steradian to
2π steradian and radiation resistance is doubled The relative acoustic energy is larger at a
distance from the wall boundary. However, this is practically impossible because it is assumed
that the audio speaker device is embedded in the wall of the room. In a typical home audio
system, the loudspeakers are placed adjacent to a room wall or other boundary, and the location
of the room boundary's impact on the loudspeaker's effective radiation angle is a function of the
frequency of the emitted sound It is eaten. At normal distances, the boundary of the room serves
to reduce the effective radiation angle for the lowest frequency audio in the audio frequency
range. In commercially available low frequency direct emission systems (i.e., woo-), it is known
that the impact of the room interface is limited to only a small fraction of the frequency range of
the loudspeaker. As a result, although the sound output can be made constant by operating
without changing the radiation resistance, the energy radiated from the frequency response
curve fluctuates with the frequency of the sound according to the frequency response curve. This
is of course a disadvantage, and the realization of low frequency audio speaker systems with flat
frequency response curves has been an equal goal for audio designers. The present invention
provides a direct emission speaker system in which the frequency response curve is improved,
particularly in the low frequency range of a typical Eau de Io system. That is, the system
according to the present invention provides a system in which the effective radiation angle of the
speaker system hardly changes as the frequency starts in the low frequency range (band).
To this end, the room audio speaker system according to the invention is made in combination
with the interface of at least one room. In this speaker system, the closed end wall is in close
contact with the boundary surface, the both side walls extend away from the end wall, and the
leading edge is integrated with the end wall to form a bordering trailing edge. Equipped with a
closed box. The direct emission type audio reproducing apparatus is an angle between the end
wall and a portion having an angle of 900 or less, substantially parallel to a portion of at least
one exposed surface of the side wall. Mounted flush with. The distance along the side wall from
the center of the regenerator to the rear border edge of the side wall is less than half the
minimum outside dimension of this side wall. Preferably, one side wall lies in one plane, and the
reproduction device is a cone-shaped loudspeaker which extends over a frequency range of at
least 100 Hz. An embodiment of the speaker system of the present invention will be described
according to the attached drawings. The sound image principle helps when considering the
impact of the effective radiation angle on a speaker system placed relatively close to one or more
interfaces of the room (i.e. floor, ceiling, wall). When placing a relatively small sound source at a
distance X from the boundary of a large room, another sound source (for the true sound source)
exists at the same distance X where the boundary does not exist or is opposite to the boundary.
As in the case of the sound image, the effect in this case is very large. In this model, therefore,
two sources of equal intensity and in phase oscillation will be separated by a distance 2x. The
small part of one wavelength where the frequency of the sound to be radiated is sufficiently low,
even at a distance 2x, the emissions from the two sounds are combined virtually in phase in all
directions, and the acoustic energy radiated is truly Of the energy that the sound source emits
when the boundary is crawling. Similarly, the boundary reduces the effective radiation angle by
half. The active space of the loudspeaker's diaphragm is mounted flush to the interface, the
frequency then acting such that the distance 2X is only a fraction of the wavelength. On the other
hand, as the frequency increases, the wavelength decreases and the effect of the upper 2
changes. When X is at a frequency corresponding to 1⁄4 wavelength, the radiation from the
sound image reverses 1800 phases at the true source. For this reason, radiation in the direction
perpendicular to the room boundary is canceled by all children, and the total energy output (total
of the acoustic energy emitted in all directions) is half of the low frequency energy mentioned
above. Become.
In other words, the energy output of this sound source is the same as when there is no boundary
anywhere. When this frequency is 0 or more, the radiation angle at the boundary is hardly
affected, and the energy output size is not affected. FIG. 4 shows this effect as calculated and
plotted as a function of frequency for a pair of single-sources separated by half the wavelength at
160 H2. Since the wavelength at 160 Hz is about 23 meters (7 feet), the above-mentioned 9plurality of sound sources are separated by 1, 15 meters (85 feet). (This corresponds to a single
sound source placed at 0.58 meters (1, 75 feet) from the large boundary of the room. 4.)
According to FIG. 4, the basic output level (zero dB) corresponds to the output level of a true
sound source emitting at a radiation angle 4π (no border near). From FIG. 4, the presence of the
interface increases the acoustic energy output according to the effective radiation angle by half
at a very low frequency, and the distance from the sound source is a frequency greater than a
quarter wavelength (more than 160 Hz). The effect on the effective radiation angle at There is
another factor that changes the effective radiation angle with frequency, especially at low
frequencies. It has already been mentioned that the area near the boundary of the room is a
factor. Because it is convenient for a particular speaker (eg, woofer) to be attached to the bottom
of the cone on one panel face of the speaker EndPage: 3 cabinet, the panel itself creates an
effective boundary wall and the panel's minimum dimension is 2 The effective radiation angle
can be limited to 2π steradians or less when the frequency is equal to or more than a half
wavelength or more. The third factor is present as well. Install two speakers driven in phase and
in synchronization in the same cabinet (for example, two woofers) in the same cabinet, and these
speakers have a sound pressure near the boundary and this speaker Behaves in the same way as
the sound image. Each speaker has a very low frequency and a small effective radiation angle,
especially at the corresponding frequencies when the span along the speaker cabinet plane
between the centers of both speakers is as small as half a wavelength This is even more so. In the
vicinity of these loudspeakers, the combined output of the loudspeakers at low frequencies is
thus doubled. However, if the speakers are separated by more than a half wavelength, the effects
of the speakers become negligible, and each speaker emits energy as if the other speakers were
As mentioned above, in a normal direct radiation speaker system, according to the present
invention, there are three factors which can change the effective radiation angle (and hence
change the radiation output according to the frequency) in relation to the frequency. It was
understood to do. These three factors operate within the same frequency range: (1) near the
interface of the room, (2) the dimensions of the mounted panel, and (8) the same frequency
range. The various couplings between the drive parts are summarized. According to the
invention, due to the relationship between these factors, the factors are determined so that the
frequency response curve is much flatter than in a typical loudspeaker system, effectively making
the effective radiation angle a frequency. It does not matter. . In particular, the distance from the
center of a single low frequency speaker to the boundary of one or more rooms along the surface
of the speaker cabinet is about half or less of the minimum dimension of the panel of the speaker
cabinet with the single speaker attached. It turned out that it must be done. Furthermore, when
two or more speakers of this type are housed in the same sealed box and their operating
frequency ranges overlap, the distance from the center of each speaker to one or more room
boundaries is the panel to which each speaker is attached 18-etc., The distance between the
centers of the two loudspeakers and the distance along the surface of the cabinet of the cabinet
is smaller than the smallest dimension of the respective panels on which the loudspeakers are
mounted. It must be small. FIGS. 1-8 illustrate a sealed box of a speaker capable of well
distributing the intermediate and high frequency sounds in the listening space while satisfying
the various conditions described above. The mid-frequency speakers and high-frequency v
speakers distribute the sound well in the room, while the low-frequency sand river speakers
center, the cabinet attachment is for any frequency that is higher than the frequency at which the
panel is the effective interface itself. And at least one chamber boundary surface is placed closer
to a quarter wavelength. In this way, the interface of the room helps the cabinet mounting to
effectively reduce the radiation angle for the frequency at which the panel is enabled to reduce
14-EndPage: 4. According to FIG. 1A, the direct-radiating speaker system 10 is more than a boxlike cabinet with a front wall 12, side walls 14, end walls 16, a bottom wall 17 and a top wall 18.
The intermediate frequency speaker 20 and the high frequency speaker 22 are flush with the
front wall 12. The low frequency speaker z4 is mounted flush with one side wall 14.
The dimensions of the car vignette can be adjusted as long as the above-mentioned relationship
is maintained, but in the embodiment of FIG. 1, the front wall has 3 (ly ++ X 60 c! n, and the side
wall 14 may have a spread shape of about 30 cm × 80 crn. As shown in FIG. 1A, the loudspeaker
according to the invention rests on a table 11 in contact with the room 928 intersecting the floor
at the corner 80 and parallel to the end wall 16. FIG. 5 is a plot of the output over the low
frequency range as a function of frequency for the embodiment shown in FIG. 1A. It is clear that
the energy radiated is quite uniform over a low frequency range (ie from about 60 Hz to 500
HX). Similarly, the effective radiation angle is a constant 2π. In comparison to FIG. 6 which is
similarly plotted for a conventional speaker which is the same as FIG. 1 except that the low
frequency speaker 24 is attached to the front wall 12. This output response curve is clearly
wedge shaped. The wall acts as an effective 2π steradian interface in the low frequency region,
so that the length from this wall to the center of the low frequency speaker 24 is effectively
smaller than a quarter wavelength, thereby providing low frequency response Will increase. On
the other hand, as the frequency increases, the length from the speaker 24 to the wall further
approaches a fraction of the wavelength, and the sound output (output sound pressure level)
decreases. At 160 Hz, the above length is approximately a quarter wavelength, and as described
above, the effective radiation angle is increased to 4π steradians, and the output level is reduced
by · B dB at this time. Above 200 Hz, the radiation angle again begins to decrease to 2π
steradians, which is due to the fact that the panel (ie front wall 12 in the prior art) is bounded by
2π steradians for these high frequencies. In the embodiment shown in FIG. 1A and in the other
embodiment which also places the woofer in the end wall as well, it can be placed in the corner
formed by the two chamber boundaries as shown in FIG. It will lead to further improvement of
the characteristics in the heel range. The radiation angle is closer to the two-chamber interface
resulting in a reduction to π steradian in the operating frequency range of the woofer, so that
the output 1-novel is uniformly doubled. In FIG. 2, the low frequency speaker 24 is further
attached to the top wall 18 of the C-shaped speaker cabinet 10. The cabinet 10 is placed on the
shelf 27 at the intersection of the walls 28.29.
The speakers 24 are placed closer to the room boundary 28. 29 so that the size of the panel also
meets the aforementioned boundary conditions. In FIG. 3, the pair of low frequency loudspeakers
24 driven in phase intersects the end wall 82 along the rear boundary edge 84 of the side wall at
an included angle 450.・ 8 faces 4 (mounting. In this embodiment, the span length B along the
surface of the speaker cabinet 10 between the central portions C of the speakers 24 is equal to
or less than the minimum dimension of the panel 14a to which the speakers are attached.
According to this loudspeaker system, the amplification device 86 used is connected by a pair of
output conductors 88 which drive the loudspeaker 24 in phase. In any of the embodiments
described above, the effective radiation angle may be further reduced to increase the sound
power level of the speaker system by increasing the above described boundary conditions to one
or more room boundaries. This allows, for example, the effective radiation angle to be constant at
π steradians, given that these conditions are maintained for the walls and floors of the room.
Similarly, the effective radiation angle can be obtained by placing the speaker system 10f on the
floor surface of FIG. 8 at the intersection of the two room walls and maintaining the boundary
conditions for these floors and walls. It can be a constant value of π / 2 steradians. The
embodiments of the present invention are as follows. (1) The system according to claim 1,
wherein the panels for mounting are approximately in a single plane. (2) A claim in which the
distance between the centers of the cone-shaped speakers along the closed box is smaller than
the minimum value of the predetermined minimum dimension of the panel using at least two
cone-shaped speakers. Speaker system. (8) The system according to claim 1, wherein said cone
speaker is driven in phase.
4. Brief description of the drawings] 1lJ-Figures 1A, IB, 2.8 are outline views of the audio speaker
system according to the present invention, and Figures 4-6 are frequency response curves of
some indoor audio speaker systems. . IO-one skier system 28-one first interface 26--second
interface 20.22.24-one cone-shaped loudspeaker 12--front "14-m-side 16- -Center 21-20 of FIG.
2 C--cone-shaped speaker, 18 FIGB End Page: 6 pieces of frozen sheet () 1) 5. List of attached
documents (4) Drawings-6 o'clock Agent address other than the above 2nd branch, Otemachi,
Chiyoda-ku, Tokyo 2nd, 1st EndPage: 7
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