JPH1153056

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DESCRIPTION JPH1153056
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to
portable computer systems, and more particularly, to a speaker cabinet with sound paths built
into the portable computer system.
[0002]
BACKGROUND OF THE INVENTION Conventional portable computers in general use a structure
in which a speaker is housed in a closed speaker cabinet, but such a structure causes mechanical
distortion and magnetic distortion as the speaker excursion becomes large. The speaker
excursion was kept small because there was a possibility that the target distortion might occur.
Speaker excursions mean that the various components of the speaker, such as the winding, voice
coil, front plate, back plate, and cone, move up and down when the speaker is facing up, and thus
move in and out. , That is the size of the movement. As mechanical distortion that may occur due
to an increase in the speaker excursion, the speaker winding may collide with the front plate or
the rear plate of the speaker, or may be provided near the center of the speaker to provide a cone
and a frame. That are connected by a crimped member (referred to in the industry as a corn
center support member ) by being overstretched, and that it is provided near the top end of the
speaker facing upwards and the frame The elastic members attached to the curved shape
(referred to in the industry as "cone edge support members") are produced by being stretched
until they are completely flat.
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[0003]
A loudspeaker is an electroacoustic transducer that uses magnetic circuits to produce acoustic
radiation. When the current supplied to the speaker flows through the voice coil, a magnetic field
is generated. When the polarity of the current alternates like a sine wave, a magnetic wave
propagates across the gap between the voice coil and the permanent magnet. The gap between
the permanent magnet of the loudspeaker and the voice coil serves as the main flux resistance or
reluctance of the loudspeaker's magnetic circuit. As a result of propagation of the magnetic wave
across the gap, the magnetic field of the voice coil repels or attracts the magnetic field of the
permanent magnet. This causes an up and down motion when the speaker is facing up, and the
motion causes the density of air molecules around the cone of the speaker to be rough.
[0004]
SUMMARY OF THE INVENTION As the speaker excursion increases, the various components of
the speaker become less likely to deflect, thus increasing the force factor of the component. As
the force coefficient increases, the reaction force increases, causing mechanical non-linearity. On
the other hand, the relative positional relationship between the voice coil and the gap determines
how large the magnetic non-linearity exists. That is, the speaker excursion that generates a great
deal of magnetic non-linearity is a speaker excursion that causes the voice coil to protrude out of
the gap. The greater the amount that the voice coil extends out of the gap, the more magnetic
non-linearity becomes more pronounced.
[0005]
Since mechanical distortion and magnetic distortion may occur as described above, the speaker
excursion associated with the acoustic radiation in the low frequency region has been suppressed
to a low level for the speaker of the portable computer. In addition, since space constraints are
particularly severe in portable computers, it has been a particularly serious problem that
mechanical distortion and magnetic distortion may occur if the speaker excursion is large. On the
other hand, the sound pressure level of the speaker housed in the speaker cabinet with the sound
path has the property of being sharply lowered in the low frequency region. Thus, the low
frequency range acoustics of portable computer speakers were significantly inferior to the high
quality low frequency range acoustics of speakers housed in a separate speaker cabinet.
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[0006]
SUMMARY OF THE INVENTION The present invention forms a port in a speaker cabinet that
houses the speakers of a portable computer. The speaker cone is made to transmit an acoustic
output of a frequency above a predetermined low frequency, and the sound path is made to
transmit an acoustic output of a frequency below the low frequency. As described above, in the
present invention, by causing the sound output in the low frequency region to be sent to the
sound path instead of the speaker cone, the speaker excursion can be reduced and the possibility
of mechanical damage to the speaker can be reduced. ing.
[0007]
Furthermore, in the present invention, a speaker cabinet that houses the speakers of the portable
computer is designed to be particularly suitable for the portable computer. The speaker cabinet
is formed into a shape conforming to the shape of components disposed adjacent to the speaker
cabinet inside the portable computer, to mention some of the key points in the design of the
speaker cabinet. In some cases, the speaker cabinet may be formed to fit within the surface area
of the portable computer housing, and the sound path may be disposed in a plane different from
the plane in which the speaker cone is disposed. Furthermore, in the present invention, in order
to suppress the speaker excursion, the input signal to the speaker may be subjected to electrical
filtering. This electrical filtering can improve the acoustic output of the low frequency region and
at the same time reduce the risk of mechanical damage to the loudspeaker.
[0008]
DETAILED DESCRIPTION OF THE INVENTION Specific embodiments of the present invention will
now be described in detail with reference to the drawings. FIG. 1 is a perspective view of a
portable computer case C housing a computer system, showing the case C in an open state. The
portable computer case C comprises an upper housing 10 in which a display screen 12 and other
components are housed. The portable computer case C further comprises a lower housing 14 in
which a keyboard and other components are housed. In this preferred embodiment of the
invention, the sound box equipped speaker cabinet E according to the invention, which is shown
in dotted lines in the figure, is accommodated in the lower housing 14. Two curved portions of
the speaker cabinet E extend from each of the two speakers L to the side surface 22 on the front
side of the lower housing 14, and these curved portions are the sound path P according to the
present invention. Therefore, the openings 23 of the sound paths P are formed on the side
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surface 22 on the front side of the lower housing 14. It is preferable to attach a cushion member
25 to each of the openings 23 of the sound paths P so as to surround the mouth edge thereof. It
is between the sides and serves as a sound absorbing material.
[0009]
The sound-guided speaker cabinet E is shaped to match the shape of the components disposed
inside the portable computer case C adjacent to the speaker cabinet E. Further, the speaker
cabinet E is sized to fit substantially in the surface area of the lower housing 14 between the
upper surface defining member 18 and the lower surface defining member 20. The upper
surface defining member 18 and the lower surface defining member 20 are preferably made of
synthetic resin or other suitable flexible material. As another embodiment different from the
above, the speaker cabinet E with a sound path may be housed in the upper housing 10 of the
portable computer case C.
[0010]
2 and 4 are side views (a rear view and a front view) of the speaker cabinet E with a sound path
according to the present invention. The sound-guided speaker cabinet E according to this
preferred embodiment is configured to accommodate two speakers L. Each of the two speakers L
is housed in a separate speaker box portion 24 integrally formed in the sound-guided speaker
cabinet E. The upper portion 28 of each speaker box portion 24 is formed by the speaker cabinet
upper member T (FIG. 5), and the lower portion 26 of each speaker box portion 24 is formed by
the speaker cabinet lower member B It is done. It is preferable to bond the speaker cabinet upper
member T and the speaker cabinet lower member B using an adhesive tape 30. In order to
connect the wiring cords 32 to the respective speakers L, the speaker cabinet E is provided with
holes for inserting the respective wiring cords 32. Each speaker L is connected to an acoustic
signal generator, which is, for example, a CD-ROM drive 33 via a wiring cord 32.
[0011]
FIG. 3 is a plan view of the speaker cabinet E. As shown in FIG. The two loudspeakers L are
preferably arranged equidistant from one another from the center point of the loudspeaker
cabinet E, which is also the case in this preferred embodiment. Furthermore, it is preferable to
attach a cushion member 34 to each of the speakers L so as to surround the peripheral portion
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thereof. Each cushion member 34 functions as a sound absorbing material, and is preferably
formed of a material such as polyether urethane foam. As described above, by providing the
cushion member 34 as a sound absorbing material between the speaker L and the upper surface
defining member 18 of the lower housing 14, the chattering noise which may be generated due
to the vibration of the speaker L is suppressed small. Can. In this preferred embodiment, a foam
member 36 is disposed on the side of each speaker L remote from the center of the speaker
cabinet E in proximity to the speaker L. The foam members 36 function as sound absorbing
members provided between the respective speakers L and the right side surface 38 to the left
side surface 40 of the lower housing 14.
[0012]
FIG. 5 is a partially exploded view for showing the components of the speaker cabinet E with a
sound path, which are shown together with the upper surface defining member 18 and the lower
surface defining member 20 of the lower housing 14. The sound-guided speaker cabinet E
includes a speaker cabinet upper member T, a speaker cabinet lower member B, and two sound
passage cover members 42. The speaker cabinet upper side member T is formed with an opening
44 matched to the size of the cone 58 of the speaker L. In the present invention, the sound path
cover member 42 is used to cover the inner surface 46 of each sound path P formed on the
speaker cabinet lower side member B. Accordingly, the sound path cover member 42 defines the
upper wall portion of the sound path P, and is for causing air to properly enter and exit the
sound path P. In this embodiment, the speaker cabinet upper member T, the speaker L, the sound
path cover member 42, and the speaker cabinet lower member B are all upper surface defining
members of the lower housing 14 of the portable computer case C. 18 is accommodated between
the lower surface defining member 20 and the lower surface defining member 20.
[0013]
FIG. 6 is a cross-sectional view of the speaker L accommodated in the speaker cabinet E with a
sound path. Conventional portable computers generally employ a structure in which a speaker is
housed in a closed speaker cabinet, but such a structure causes mechanical distortion and
magnetic distortion when the speaker excursion becomes large. I was trying to keep the speaker
excursion small because there is a risk. In the speaker excursion, various components of the
speaker L such as the winding 50, the voice coil 52, the front plate 54, the back plate 56, and the
cone 58 move vertically when the speaker L faces upward, Therefore, it moves inward and
outward directions, but the size of the movement. As mechanical distortion that may occur due to
the increase of the speaker excursion, the distortion due to the winding 50 of the speaker L
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colliding with the front plate 54 or the rear plate 56 of the speaker L, or near the center of the
speaker L By overstretching a crimped member 60 (referred to in the art as "corn central
support") which is provided to connect the cone 58 and the frame 64, with the loudspeaker L
facing upwards Such as those produced by stretching a curved shaped elastic member 62
(referred to in the art as a "cone edge support member") provided near the upper end of the case
and attached to the frame 64, etc. until it is completely flat There is.
[0014]
The loudspeaker L is essentially an electroacoustic transducer that uses magnetic circuits to
produce acoustic radiation. When the current supplied to the speaker L flows through the voice
coil 52, a magnetic field is generated. When the polarity of the current alternates like a sine
wave, a magnetic wave propagates across the gap 53 between the voice coil 52 and the
permanent magnet 66. The gap 53 between the permanent magnet 66 of the speaker L and the
voice coil 52 serves as the main flux resistance or reluctance of the magnetic circuit of the
speaker L. As the magnetic wave propagates across the gap 53, the magnetic field of the voice
coil 52 repels or attracts the magnetic field of the permanent magnet 66. As a result, an upward
and downward motion occurs in the upward speaker L, and the motion causes the density of air
molecules around the cone 58 of the loudspeaker L to be rough.
[0015]
As the speaker excursion increases, the various components of the speaker L become less likely
to flex, thus increasing the component's force factor. As the force coefficient increases, the
reaction force increases, causing mechanical non-linearity. Also, the relative positional
relationship between the voice coil 52 and the gap 53 can be known from the magnitude of the
magnetic non-linearity. That is, the speaker excursion that generates severe magnetic nonlinearity is a speaker excursion that causes the voice coil 52 to protrude out of the gap 53. As the
amount of voice coil 52 protruding out of gap 53 increases, the magnetic non-linearity becomes
more pronounced.
[0016]
Since mechanical distortion and magnetic distortion may occur as described above, the speaker
excursion associated with the acoustic radiation in the low frequency region has been suppressed
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to a low level for the speaker of the portable computer. In addition, since space constraints are
particularly severe in portable computers, it has been a particularly serious problem that
mechanical distortion and magnetic distortion may occur if the speaker excursion is large. As a
result, the low frequency range acoustics of the portable computer speakers were significantly
inferior to the high quality low frequency range acoustics of the speakers housed in the separate
speaker cabinet.
[0017]
FIG. 7 shows speaker excursions of the speaker system of a portable computer using a
conventional closed cabinet and the speaker system of a portable computer using a speaker
cabinet with a sound path according to the present invention. It is a graph plotted against
frequency. In a speaker system using a closed speaker cabinet, the speaker excursion exceeds a
safe displacement level at a predetermined low frequency fprf, which may cause damage to the
speaker system. Note that in FIG. 7, the recommended maximum excursion level 68 is assumed
to be -20 dB. In the frequency range lower than the predetermined low frequency fprf, the
loudspeaker excursion curve 70 corresponding to the enclosed loudspeaker cabinet exceeds the
recommended maximum excursion level 68 as shown by the broken line in the figure, so that
mechanical distortion is caused. And the possibility of magnetic distortion is increased. On the
other hand, the speaker excursion curve 72 corresponding to the sound-guided speaker cabinet E
according to the present invention does not exceed the recommended maximum excursion level
at the above-mentioned predetermined low frequency fprf. Furthermore, the speaker excursion
curve 72 by the speaker cabinet E with the sound path has a shape that turns up at a certain
frequency after rising once, so this curve 72 has a certain bandwidth of a predetermined low
frequency fprf or less. Even in the frequency domain, it is at a level lower than the recommended
maximum excursion level 68.
[0018]
Assuming that the speaker excursion curve 72 by the speaker cabinet E with a sound path is a
frequency that is lower than the recommended maximum excursion level 68 above the frequency
by fbd, the speaker cabinet E with a sound path is The present invention exerts an effect on
acoustic radiation in a frequency range between the frequency fbd and the predetermined low
frequency fprf described above. Although the frequency range in which the speaker system using
the conventional closed speaker cabinet can properly emit the sound output energy is limited to
the frequency range exceeding the frequency fprf, the speaker with the sound path according to
the present invention In the speaker system using the cabinet E, the acoustic output can be
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properly transmitted even in the frequency range between the frequency fbd and the frequency
fprf. The region width between the frequency fbd and the frequency fprf corresponding to the
difference between the two frequency regions is about one octave. From the above, it can be seen
that the speaker cabinet E with sound path according to the present invention improves the
acoustic characteristics in the low frequency region.
[0019]
The speaker excursion curve 72 of the speaker cabinet E with a sound path shown in FIG. 7 is an
excursion curve when the sound path P of the speaker cabinet E is tuned to the above-mentioned
predetermined low frequency fprf. At this frequency fprf, the sound path P functions as an
acoustic resonator in place of the speaker cone 58. Therefore, this frequency fprf is called a
sound path resonance frequency (Port Resonance Frequency). The sound path resonance
frequency fprf is a function of the compliance of the sound path P and the mass of a mass of air
contained in the sound path P. Therefore, the resonance frequency of the sound path P can be set
by adjusting the compliance and the mass.
[0020]
When the sound path P is tuned to a resonance frequency, an impedance load whose center
frequency is at the resonance frequency is loaded to the driving unit D as a back load. Here, the
drive part D is a term that collectively refers to components other than the cone 58 among
components of the speaker L (see FIG. 5). Therefore, the speaker cone 58 does not vibrate at all
at the sound path resonance frequency fprf, but hardly vibrates, and thus does not function as an
acoustic radiator. As described above, in the low frequency region, the sound path P functions as
an acoustic radiator instead of the speaker cone 58, thereby suppressing the excursion of the
speaker L to a mechanical damage to the speaker L and the driver D. Reduce the risk of
[0021]
When using a speaker cabinet with a sound path, it is known that the slope of the speaker
excursion curve becomes steep in a certain frequency range. In such a frequency range, a slight
decrease in frequency results in a significant increase in sound pressure level. Speakers used in
portable computers are susceptible to excursions because their components are small, and so on,
and so it is not possible to use speaker cabinets with sound paths, as in conventional portable
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computers. there were. In this regard, in the present invention, the method of suppressing the
speaker excursion of the frequency lower than the specific low frequency fbd may be used in
combination by applying the electric filtering process to the electric signal input to the speaker. .
Thus, the possibility of damage to the speaker L and the drive unit D can be reduced by
suppressing the speaker excursion to a small value. Therefore, the present invention provides a
speaker cabinet E with a sound path built in a portable computer case C which can reduce the
possibility of mechanical damage to the speaker L and the drive part D.
[0022]
As is apparent from the above, in the present invention, the sound path P is formed in the
speaker cabinet E incorporated in the portable computer. Therefore, the possibility of mechanical
distortion and magnetic distortion of the acoustic signal due to the speaker excursion can be
greatly reduced. Furthermore, the dimensions of the sound path P, such as length, width and
degree of curvature, should be sized to deliver an appropriate acoustic output in a predetermined
low frequency region, and also inside the portable computer. It should also be noted that the
dimensions and shapes of the components arranged at positions adjacent to the speaker cabinet
E are made to match. The above disclosure and description of the present invention are intended
only to present specific examples of the present invention, and the dimensions, shapes, materials,
components, circuit elements, connection of wiring, and forms of contacts are presented.
However, various changes can be made to the detailed configurations and operation modes of the
circuits and structures specifically shown without departing from the concept of the present
invention.
[0023]
Brief description of the drawings
[0024]
1 is a perspective view of a computer case housing the computer system, showing the computer
case in an open state.
[0025]
2 is a rear view of the speaker cabinet device according to the present invention.
[0026]
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3 is a top view of the speaker cabinet device of FIG.
[0027]
4 is a front view of the speaker cabinet device of FIG.
[0028]
5 is a partially exploded perspective view showing the various components of the speaker
cabinet apparatus of FIG. 2, showing the components together with the top and bottom defining
members of the portable computer housing .
[0029]
6 is an enlarged cross-sectional view of the elliptically enclosed speaker indicated by reference
numeral 6 in FIG.
[0030]
Fig. 7 The frequency of the speaker excursion is the frequency of the speaker housed in the
conventional sealed computer for portable computer and the speaker housed in the speaker
cabinet with sound path for portable computer according to the present invention It is a graph
plotted against.
[0031]
Explanation of sign
[0032]
B Speaker Cabinet Lower Member C Portable Computer Case E Loudspeaker Speaker Cabinet D
Drive Part L Speaker P Loudspeaker T Loudspeaker Cabinet Upper Member 42 Sound Canal
Cover Member 52 Voice Coil 58 Speaker Cone
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