JP2002532038A - Sound equipment - Google Patents

Abstract

(57) [Summary] The present invention relates to a method for reducing feature points occurring at a specific frequency such as a coincidence frequency. The panel (11) has exciters (13, 15) configured to reduce feature points. The exciters can be driven in phase, but are spaced a distance substantially equal to the half wavelength of the bending wave in the panel at this particular frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL FIELD [0001] The present invention relates to an acoustic device including a panel-shaped member based on bending wave action due to a resonance mode distribution of surface vibration for acoustic operation, and more particularly to a panel-shaped loudspeaker.

BACKGROUND OF THE INVENTION As taught in various applications by the present applicant, including published International Patent Application No. WO97 / 09842, panel-shaped loudspeakers have an associated panel shape and flexural rigidity. And the position of the panel exciter or the panel exciter is optimized. Even if optimized, if some frequencies are candidates for variation of their contributions during operation, for example, a substantial suppression, a rather troublesome reduction of their contributions may be beneficial. is there. Indeed, one example is related to the coincidence frequency, which results in directional radiation at a very large angle to the panel surface, at least in large panels, and an inability to exceed the size-related smoothing effects inherently useful in small panels. Cause regularity.

According to a first aspect of the present invention, a panel capable of supporting a bending wave, and a first excitation mounted on the panel to cause the bending wave in the panel to generate an acoustic output Wherein the acoustic output response of the panel driven by the first exciter has a feature at a known frequency, and furthermore, the acoustic output is attached to the panel and causes a bending wave in the panel to generate an acoustic output. A second exciter for generating, the second exciter being a flexural wave configured to smooth a characteristic point when the first exciter and the second exciter are commonly driven. A loudspeaker is provided.

[0004] The second exciter may be arranged at a predetermined interval from the first exciter to smooth the feature points. The relative phase and gain of the first and second exciters may be controlled and the second exciter may include a filter, an attenuator, a delay device, a phase control device, a signal processing device, and / or a variable gain control. A device may be provided. Generally important is the relative amplitude and phase of the signals supplied to the two exciters, so that the second
A filter, an attenuator, a delay device, a phase control device, a signal processing device, or a variable acquisition control device may be provided in association with the first exciter in place of or in addition to the exciter of (1). The second exciter may be connected in phase or out of phase with the first exciter.
Some or all combinations of these methods can be used.

A characteristic point is an acoustic output (sound pressure level) as a function of a frequency related to a constant excitation voltage.
May be peaks, protrusions or bumps at Thus, the loudspeaker according to the present invention can have an improved frequency response with smoothed feature points. The second exciter is preferably spaced from the first exciter on the panel by a distance substantially equal to a half wavelength of the panel bending wave at a known frequency. Further, it is also possible to use an odd multiple of the half wavelength, that is, a wavelength 1.5 times or 2.5 times the wavelength.

Preferably, the first and second exciters are connected in phase between the common terminals.
This can be easily achieved by connecting the same type of exciter in a ring in the same way in a series or parallel arrangement, whereby the bending waves are emitted in phase. of course,
If the exciters are separated by half a wavelength at a particular frequency, the phase relationship at that frequency will provide the desired amount of cancellation, providing suppression and / or smoothing.

If the second exciter is driven simply in phase opposition to the first exciter irrespective of the arrangement of the second exciter, the first and second exciters have a wide frequency band Over time, causing harmful interference, especially at low frequencies. Conversely, by arranging the first and second exciters separated by a half wavelength, the first and second exciters can be driven in phase and the sound output can be increased. Only at known frequencies the bending waves caused by the two exciters are out of phase and cancel. Thus, the exciter according to the invention has an improved response at a certain known frequency.

[0008] Preferably, the known frequency is a coincidence frequency. At the coincidence frequency, the acoustic characteristics of the panel do not change smoothly. Therefore, the frequency response at this frequency often has peaks or bumps. This can be smoothed with the loudspeaker according to the invention.

The panels may be anisotropic and have separate coincidence frequencies associated with the first axis and the second axis. A second exciter may be spaced along the first axis from the first exciter to smooth a coincidence frequency characteristic associated with the bending wave along the first axis, A third exciter spaced apart from the first exciter by a distance substantially equal to a half wavelength of the bending wave at the coincidence frequency associated with the second axis.

A fourth exciter may be provided, and the first, second, third and fourth exciters may be provided in a rectangular shape on the panel surface. Additional exciters may be added if desired to provide, for example, sufficient power.

The exciters may be separate transducers, for example, each exciter comprises a voice coil mounted on a panel and a magnet assembly configured to move relative to the voice coil. You may. The exciter may be inertial, i.e. the magnet assembly does not need to be fixed to a separate frame, but the forces on the panel repel the inertia of the magnet assembly. If the exciters are driven in phase, some parts can be shared. For example, the first and second exciters may comprise a single transducer having a coil and a magnet assembly, wherein the coil has a first region in contact with the panel (a first exciter) and a second region in contact with the panel. And two regions (second exciters).
The two locations are spaced apart by a half wavelength of the bending wave at a known frequency.

[0012] Preferably, the exciters are spaced apart by a certain distance, but this is not always possible. Therefore, in another embodiment, the second exciter may be arranged near the first exciter and driven in opposite phase. In this case, the second exciter is driven only in a predetermined frequency band near a known frequency using a band filter.

In an embodiment, a small number of exciters may be arranged to operate at a frequency sufficiently higher than the coincidence frequency, for example, to reduce interference effects at the coincidence frequency. This can be achieved by providing filters associated with the aforementioned exciters, only one of which operates in the high frequency band. Since this may break the electrical and mechanical balance of the first, second, third exciters, etc., one or more other high frequency exciters may alternatively be provided. . Providing a single high frequency exciter is beneficial for reducing acoustic interference effects at high frequencies.

If a separate high-frequency exciter or a plurality of high-frequency exciters is provided, the low and high frequencies in the drive signal are separated by a crossover circuit, ie a high-frequency exciter higher than the cutoff frequency and another high-frequency exciter below the cutoff frequency. It can be separated by a circuit for driving the exciter. The detailed design of the crossover circuit is well known in the loudspeaker art, and it is desirable that the crossover circuit be as steep as necessary. The crossover circuit should not be confused with the bandpass filter described above,
If convenient, the circuits may be combined.

According to a second aspect of the present invention, a panel capable of supporting a bending wave, and first and second excitations mounted on the panel to cause the bending wave in the panel to generate an acoustic output. Wherein the first and second exciters are spaced apart by half a wavelength at a predetermined frequency, and when the first and second exciters are commonly driven, the acoustic output of the panel is A flex wave loudspeaker adapted to be affected at a predetermined frequency is provided.

The first and second exciters may be connected in antiphase to increase the sound output at a predetermined frequency, or connected in phase to smooth or reduce the sound output at a predetermined frequency. Good. High responsiveness at a particular frequency is particularly useful for sirens and other audible alarms that only need to generate output at a known frequency.

For a more general requirement for a smooth loudspeaker response, the first and second exciters are connected in phase. In this case, other features described in connection with the first aspect of the present invention may be utilized if convenient.

According to a third aspect of the present invention, a frequency response of a bending wave loudspeaker having a panel (11) capable of supporting a bending wave and a first exciter (13) attached to the panel. Wherein the response of the first exciter on the panel determines the frequency having the feature point; and the first and second exciters (
13 and 15) are commonly driven so that the characteristic points are smoothed by the second exciter (
15) on a panel.

A second exciter may be provided on the panel at a half wavelength of the panel bending wave at a known frequency. The step of determining a frequency may determine a coincidence frequency associated with the predetermined direction.

According to another aspect of the present invention, a panel-shaped loudspeaker based on bending wave action having a beneficial distribution of resonant mode vibrations is based on the spacing between at least two excitation means associated with the associated panel. It has a control device for at least one frequency. This spacing is from one excitation means in a position optimized for panel excitation to additional additional excitation means, and this spacing is directly related to the speed of transmission of the bending wave in the panel for this frequency. It may be related, especially when the excitation means receives the same signal on an in-phase basis, to coincide with a half wavelength to obtain a reduction to satisfactory suppression.

The one frequency is supplied substantially only to this additional excitation means, for example via a narrow band filter, and with a delay this spacing is other than the half wavelength but substantially the same effect It is possible to fulfill. Another or further adjustment function can be realized by the delay imparted to the remaining input signal, but it is usually desirable not to differentially apply the exciters to the optimized position.

An additional second phase is provided by the antiphase relationship of the half-wavelength interval to the one excitation means.
When the exciting means is provided, the effect is opposite, and the contribution of the frequency in the sound output of the panel-shaped loudspeaker may increase.

The direction of this spacing is also important. As in another aspect of the invention, the particular direction of the spacing between the two excitation means is affected at a frequency corresponding to this spacing. The two frequencies are suitably influenced by different spacings in the same direction, typically included on either side of the excitation means in the optimal position, or in different spacings in different directions with respect to the frequencies, which are related to different directions. May be affected.

In a particular embodiment of the invention, for this frequency which is furthermore related to the length or width of one of said substantially rectangular panels, said spacing is related to this direction, ie both sides of the length or width. Or it is parallel to the axis. In fact, each frequency with respect to the length and width of such a rectangular loudspeaker, whether by additional excitation means separated separately with respect to the optimal position of one excitation means or each with a different optimal position of the excitation means It is practical to handle the minimum frequency of

If different optimal positions of the excitation means are used, spacings for the purposes of the present description, including, but not limited to, those not associated with one or more of the optimal positions used Relevance of additional excitation means spaced apart, one direction at the same spacing,
A relevance using the frequencies associated with one to all the optimal exciter positions, another opposing spacing in one direction with respect to at least one of the latter using the optimal exciter positions (ie another relevant frequency ), An association using at least one used optimal exciter position using another direction and spacing (i.e., another associated frequency), also having an association with the one direction and spacing, and the book When it is beneficial / convenient to treat each separately as far as the relevance of the additional excitation means from the same optimal position of the additional excitation means at significant intervals for the purposes of the description in another direction and at an interval There is.

At least for the band-passed affected frequency, using one normalized interval and various delays, yet another interval and optionally given delay, are substantially the same The effect is feasible.

If at least for one optimal position of the excitation means this device for one or more frequencies of interest is added, it is advantageous to apply a pass filter to the signal input and to select the selected band. Only applies to all the excitation means associated with that one optimal position.

Embodiments of the present invention that provide a reduction to suppression on a selective frequency basis include:
As will be specifically described and illustrated, it can be seen that there are applications that are particularly useful in achieving improved acoustic performance in connection with the specific problems described above with respect to coincidence frequencies. It can be seen that embodiments of the present invention that provide selective frequency-based enhancements require, for example, an alarm siren and / or have beneficial applications such as loudness and overrides for communications (results). , Operation on the selected frequency band is possible).

If the affected signal element is directional at the output from the loudspeaker panel, embodiments of the present invention may be used in connection with the desired directional effects, including reducing or enhancing it. Can be.

The device of the present invention for at least selective frequency reduction / suppression, including spaced-apart exciters operating in phase, has some equivalence for large area excitations, Thus, the use of large area excitation means can be used effectively or practically, and the unavoidable frequency band effect that can be achieved by small area excitation means at another location as well as any suitable pass filter. It can be understood that correction can be made for the following. Particular embodiments of the present invention are described below by way of example only with reference to the accompanying drawings.

BEST MODE FOR CARRYING OUT THE INVENTION Referring to the following equations (Equations 1 and 2), the dependence of the wave velocity (v) over the panel surface on the frequency is (Equation 1): This wave velocity results in a coincidence frequency (Equation 2) equal to the loss frequency coincidence frequency of the panel's wave velocity. At this coincidence frequency, for example, the polar coordinates of a large panel of 1450 mm × 1100 mm are the sound pressure level (SP) generated at the maximum angle with respect to the panel surface.
L) Will show a peak. This becomes more apparent in larger panels for a number of reasons. As the area increases, the optimum flexural rigidity (β) increases and the coincidence frequency decreases. Any "beaming" effects of the small panels are dispersed by the smearing effect associated with the panel dimensions. In addition, the peak is more pronounced because the smearing effect experienced by the large panel is small. Equation 1: v (f, β, μ) is the velocity of the wave and depends on the frequency f expressed in Hz, the flexural rigidity β (unit: Newton meters) of the panel material, and the area density μ (unit: kg / m ² ). Equation 2:

FIG. 1 shows a schematic diagram of a loudspeaker according to the invention. The panel 11 has a first exciter 13 and a second exciter 15 mounted on its surface. The microphone 17 is moved around the horizontal path 19 for measurement, and the acoustic output response is measured as a function of the angle from the center line 21 orthogonal to the panel.

As taught by the applicant's other patents and applications, such as WO 97/09842, for example, the first exciter 13 is located at an optimal excitation position to couple to resonant bending waves in the panel. I have. The second exciter is spaced from the first exciter to provide a smooth response at the maximum angle coinciding with the coincidence frequency. To this end, the spacing S between the centers of the exciters 13 and 15 is of a length equal to half the wavelength of the coincidence frequency of the wave along the horizontal axis 35.

FIGS. 2 and 3 illustrate certain embodiments of the present invention. 1450mm x 1100m
In the rectangular anisotropic panel 11 having an m dimension, the thickness of the core 25 is 10 mm, and the thickness of the epoxy skin 27 to which carbon fibers are added is 0.106 mm. The skin is attached to a core of 90 gsm (grams / m ² ) of epoxy film 29 laminated on a cotton carrier. An attachment 23 is provided to support the panel during use. A 534 gsm projection material 31 was glued to the panel using a double sided film 33 so that the panel functioned as a projection screen.

The flexural rigidity β of the panel is 184 Nm along the first major axis 35 and the second minor axis 37
Along with the area mass density was 1.92 kg / m ² . The coincidence frequency is a frequency when the wave speed of the panel is equal to the wave speed in the air at 344 m / s. Calculating using the above parameters and Equation 1, the coincidence frequency for the wave in the x direction is 1924 Hz. The length of the half wavelength at this frequency was 89.583 mm, and the second exciter 15 was attached at a position 90 mm away from the first exciter 13 along the long axis.

Although the calculations effectively correspond to point source exciters, commonly available exciters are up to about 25 mm in diameter or more. This does not have to be a point sound source,
It will require some tweaking for optimization, but should be easily found by trial and error. 5-10% maximum position error, eg about 5 m
m is expected to be true.

The sound is output at the coincidence frequency and a slightly higher frequency, that is, about 2 kHz, and has the maximum intensity at an angle of 80 degrees with respect to the center line 21 at this frequency. FIG. 4 shows the output with and without compensation using a second exciter at an angle of 80 degrees. Measurements were made using a 1 V excitation at a distance of 2 m with and without a second exciter.

The upper line in FIG. 4 is an excitation output using only the first exciter, and has a peak near 2 kHz. The improvement using both exciters 13, 15 can be easily seen from FIG. 4 and can be seen in the lower line measured using the excitation from both exciters. This line has no resonance peak.

With the use of the two exciters 13, 15, only the feature points associated with the beaming in the horizontal plane (x-axis 35) are corrected. However, beaming also occurs on the y-axis 37. Because the panel is anisotropic, the coincidence frequency and the wavelength of the wave along the y-axis are different. The half-wavelength interval at the coincidence frequency is calculated to be 54 mm in the same manner as described above. Therefore, the third and fourth exciters 17, 19 are y
It is provided at a position 54 mm away from the first and second exciters along the axis. The four exciters are arranged in a rectangle. The reason for using a rectangle is that it keeps a physical balance. This makes the mechanical impedance of the exciter substantially equal, and facilitates group driving.

FIG. 5 shows the improved results using a further pair of exciters. The thin line with a peak at 3 kHz represents the sound power at an angle of 80 degrees in the horizontal direction using only the first pair of exciters, and the thick line shows the effect of using all four exciters. As before, the peak at the coincidence frequency is substantially reduced.

The on-axis coincidence effect measured under anechoic conditions using a microphone along the centerline is very small. However, if the loudspeaker is installed in a room with reverberation, the listener will hear the sound output at all angles, which may reach the listener after reflecting off the wall. The loudspeaker according to the present invention comprises:
In these real-world conditions, even on-axis results in improved response.

A high frequency exciter 21 is provided (FIG. 2) and operates only at high frequencies. The low to middle frequencies including the coincidence frequency are the first to fourth exciters 13 and 15.
, 17, and 19. This division of the frequency band can reduce undesirable high-frequency interference effects caused by multiple drive exciters.

As shown in FIG. 6, the exciter is preferably driven by the crossover circuit 20. The first to fourth exciters are connected between the common terminals, that is, the excitation input point 22 and the ground 24.
Connected between The terminal can be connected to a signal source such as an amplifier. High frequency exciter 2
1 is connected in parallel with inductor L3, both connected in series to capacitor C3, which can be driven from a common terminal or another terminal.

The first to fourth exciters 13, 15, 17, and 19 are commonly driven, and two parallel pairs are divided in series. This exciter array is connected in series with a parallel connected inductor L2, resistor R1 and capacitor C2 that provide a weak filter to provide additional limiting of the frequency response. The weak filter is then connected to input 22 via inductor L1 and to ground 24 via capacitor C1 to provide a low pass effect. The values of the illustrated components are as follows. L1 is 0.92 mH (low resistance), L2
Is 5.0 mH, 0.4Ω, L3 is 0.9 mH (low resistance), C1 is 6.8 μF, C
2 is 100 μF, C3 is 6.8 μF, and R1 is 30Ω.

FIG. 7 shows another configuration for driving the four exciters 13, 15, 17 and 19. In this configuration, two of the first through fourth exciters are bridged by a capacitor 39 that shorts out the high frequencies. In this way, only two exciters are driven at a high frequency.

FIG. 8 shows a variant of the previous embodiment with a further exciter. 1st to 4th
Is the same as that of the above-described embodiment. In this entire system, the fifth exciter 41 and the sixth exciter 43 are provided at appropriate positions so as to couple with bending waves in the panel. The seventh exciter 45 and the eighth exciter 47 are respectively the fifth exciter
And a sixth exciter and are spaced apart from them along a horizontal axis 35. The reason for this is that irregularities due to directivity in the horizontal plane to the listener are significantly more significant than vertical irregularities, and such irregularities are compensated for by horizontal spacing. is there. The ninth exciter 49 is also spaced apart from the fifth exciter and at a different distance along the first axis in a direction opposite to the seventh exciter.

FIG. 9 shows a crossover circuit for a system of a total of nine exciters.
FIG. 10 shows the calculated, ie simulated, electrical impedance.
The resistance drops to a minimum of 8Ω between about 12 kHz and 500 Hz. This is particularly advantageous for input signal amplifiers and, if necessary, for loudspeaker panels 3.
Room can easily be provided for connecting another system in parallel with zero, and the possibility of overloading the amplifier is reduced. In fact, the crossover circuit can activate only the fifth exciter 41 for high frequency sound output radiation, which is effective to add another improvement in high frequency response.

The nine exciter systems of FIG. 8 beneficially optimize the effects on the angular accuracy of the sound output action and the extension of low frequency operation. The measurement results of the reverberation response are shown in FIG. 8 on an on-axis basis with an angle base of up to 80 degrees.

The exciters used in this embodiment provide excellent control over directivity, increase maximum SPL level and increase bandwidth. This control is achieved by effectively nullifying or causing detrimental superposition on the selected bending wave in the panel, the frequency range affected being controlled by the specific location of the exciter in the panel area. SPL removal of up to about 10 dB, or a coincidence frequency that would otherwise occur at a maximum angle to the panel surface can be easily contained.

The typical large loudspeaker shown in FIGS. 1 and 2 often functions as a center channel loudspeaker and also serves as a so-called home movie or multimedia device visual screen. Normally, the panel 11 can be attached to the wall by the fixture 23 according to the frame specification, and a decorative edge can be attached to the front surface of the panel 11. Low frequency performance can be enhanced by minimizing the spacing between the panel and the back wall and further attaching a layer of sound absorbing material such as a foamed polyurethane sheet to the back of the panel and its orthogonal frame, for example, 800
It gives a sound absorption above Hz and a rear spacing of about 40 mm to about 80 mm.

The dimensions shown in FIGS. 1, 2 and 8 are all exemplary. Some of the exciters marked with crosses in FIG. 8 are arranged at optimal positions by distributed mode leaching according to, for example, W097 / 09842.

An arrangement of four exciters can be used in a series-parallel combination so that all exciters operate on a full range basis, resulting in a load on the signal supply amplifier of, for example, 6Ω. Alternatively, input signal frequencies beyond the band that offset the effects associated with the coincidence frequency can be radiated from exciters 13 and 15 by connecting a high-pass filter to another exciter. See the capacitor 39 in FIG. This creates a high frequency lift (variable by a resistor connected in series with the capacitor 39, if necessary) and reduces interference effects at high frequencies that can be heard by listeners walking around the panel. As described above, in order to maintain a balance between the canceling exciters related to the mechanical action in the canceling band, the phases of the currents flowing through the respective exciters should not change as much as possible, and perform any necessary corrections. Need to be done, for example, a 6 μF capacitor results in a 12 degree current phase shift at 2 kHz, which is equivalent to a 3 mm spacing reduction, FIG.
Can be corrected by increasing the distance between the pair of exciters 13, 15 and 17, 19 by 3 mm. By using a series resistor having the capacitor 55, the correction variation of the interval can be reduced.

Since most of the panel is not on the line connecting the exciters, the additional exciters have little effect on the non-reflective on-axis frequency response. Thus, most panel surfaces experience orthogonal bending wave effects caused by normal exciter positions. Measurements of the reverberation response (in a room) show an improvement when using this method, as reflections from walls, ceilings and floors have an additional smoothing effect.

FIGS. 11 and 12 show the calculation results of the panel displacement. When the bending wave panel vibrates, the displacement of the panel occurs in connection with the bending wave action. Instead of the simple front-to-rear displacement of the entire panel that occurs with conventional piston loudspeakers, a more complex displacement pattern results. FIG. 11 shows the calculation result of the panel displacement using the exciters arranged at two intervals at 71 and 73, and FIG. 12 shows the panel displacement using only one exciter at 71 for comparison. Show. Both figures show the calculation results using the energy supplied by the exciter at the coincidence frequency. Both panels have one panel
It is simplified in that it is modeled as one length dimension and one vertical dimension. Thus, some of the complexity of the actual two-dimensional panel, which deflects to cause a displacement in the third dimension, is lost. Nevertheless, the results show that the large panel displacement at coincidence frequency using only one exciter seen in FIG.
It can be seen that the arrangement of FIG. 11 with two exciters substantially cancels out.
In the acoustic domain, this effect reduces the sound pressure level at a maximum angle to the panel surface at the coincidence frequency. This is because the displacement of the large panel combines with the air to produce sound at the maximum angle, which reduces this coincidence effect (known as beaming).

The on-axis sound pressure for one or two exciters for FIGS. 11 and 12 was calculated. The result is shown in FIG. The results for one exciter are shown by the lower solid line, and the results for two exciters are shown by the upper dotted line. The two exciters produce twice as much output, so the dotted line is about 3 dB higher in sound pressure level than the solid line output. This result was calculated for the anechoic case, ie, without considering any reflection. No peak is observed in the sound pressure response of the frequency characteristic in either of the one or two exciters. This is because the peak at the coincidence frequency emits sound at the maximum angle to the axis. Therefore, in order to show the effect of using two exciters, it is necessary to consider the angle dependency of the sound pressure level.

FIG. 14 shows sound pressure levels emitted in various directions at a frequency substantially lower than the coincidence frequency of 541.7 Hz. It can be seen that the radiation is substantially isotropic at this frequency. FIG. 15 shows the results at the coincidence frequency (2039 Hz). Results from only one exciter show very large peaks and dips at maximum angles. These peaks and dips are substantially smoothed in the case of two exciters. FIG. 16 shows the result at 4515 Hz, which is sufficiently higher than the coincidence frequency. No cancellation occurs at this frequency.

Another way of expressing these results is to integrate all sound pressure levels over all angles as a function of frequency. FIG. 17 shows the results with one and two exciters. The peak at the coincidence frequency (around 2000 Hz) is clearly greater for one exciter than for two exciters.

The results of these calculations were verified using measurement samples. As shown in FIGS. 18 and 19, the test sample is made of a 3.5 mm thick aluminum honeycomb 51 having a carbon fiber skin 53 and a vinyl cover 55 laminated on the front surface with a 50 gsm thermoplastic ground cloth. . The panel is a rectangular panel measuring 220 mm along the short axis 57 and 440 mm along the long axis 59. The first and second exciters 61, 63 are mounted on a panel, each 25 mm exciter,
It is connected to the panel using a lightweight ring. The first exciter 61 is provided at a position of 94 mm in the short-axis direction and 195 mm in the long-axis direction as measured from the nearest corner, and the second exciter 63 is provided with the first exciter near the nearest corner. 22.5 from axial direction
It is mounted at an angle of degrees and 43 mm from the first exciter.

FIG. 20 shows a sound output measurement result of a panel driven by the first exciter 61,
FIG. 21 shows the result of driving by both the exciters 61 and 63. In both figures, 2
The data below 00 Hz could not be accurately measured by the measuring device, and should be ignored. Comparing these graphs, it can be seen that the peak at the coincidence frequency (around 3600 Hz) is substantially lower when two exciters are used than when one exciter is used.

Unlike the large panels of FIGS. 2 and 8, this panel is considerably shorter in the short axis direction (2
20 mm), coincidence beaming in this axial direction is not a major problem. Thus, good results can be obtained using only two exciters.

FIG. 22 shows that the first exciter 13 and the second exciter 15 are arranged adjacent to each other, and the second exciter is connected to the first exciter via the band-pass circuit 81 and the lead wire 83. 3 shows another device connected in anti-phase. As mentioned above, the device can be used with intervals other than the half-wavelength of the feature point between the exciters.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a loudspeaker according to the present invention.

FIG. 2 is a plan view of the first embodiment of the present invention.

FIG. 3 is a side view of the first embodiment.

FIG. 4 is a graph of sound output at an angle of 80 degrees horizontally with respect to the vertical axis, using two horizontally spaced exciters, using a single exciter. Compared to the case.

FIG. 5 is a graph of sound output at an angle of 80 degrees perpendicular to a vertically oriented vertical axis, using two vertically spaced exciters, with a large spacing. This is compared with the case of multiple exciters arranged without.

FIG. 6 shows a crossover circuit according to the first embodiment.

FIG. 7 shows another crossover circuit.

FIG. 8 shows a second embodiment having nine exciters.

FIG. 9 illustrates a crossover circuit according to a second embodiment.

FIG. 10 shows an electrical impedance in the second embodiment.

FIG. 11 shows simulated panel displacements for a one-dimensional sample using two exciters.

FIG. 12 shows a simulated panel displacement for the sample of FIG. 11 driven by only one exciter.

FIG. 13 shows the on-axis sound pressure response in the arrangement of FIG.

FIG. 14 shows sound pressure at 541.7 Hz as a function of angle.

FIG. 15 shows sound pressure at 2039 Hz as a function of angle.

FIG. 16 shows sound pressure at 4515 Hz as a function of angle.

FIG. 17 shows sound pressure integrated over all angles.

FIG. 18 shows a plan view of a loudspeaker according to the invention.

19 shows a side view of the loudspeaker shown in FIG.

FIG. 20 shows the measurement results for the panel driven by one exciter in FIGS. 18 and 19;

FIG. 21 shows the measurement results for a panel driven by two exciters in FIGS. 18 and 19;

FIG. 22 shows yet another device.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] October 5, 2000 (2000.10.5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID , IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, (72) Invention of NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZA, ZW Person Stearns Mark United Kingdom Cambridgeshire P.E. 28 4T Huntingdon Brampton Renton Close 5F Term (Reference) 5D012 AA02 BA03 CA02 FA03 GA01 5D016 AA01 FA00

Claims (26)

[Claims] 1. A panel (11) capable of supporting a bending wave, a first exciter (13) mounted on the panel (11) and causing a bending wave in the panel to generate an acoustic output. Wherein the acoustic output response in the panel (11) driven by the first exciter (13) has a characteristic point at a known frequency, and further mounted on the panel (11). A second exciter (15) for generating a sound output by causing a bending wave in the panel, wherein a position, interval, direction, phase, phase, of the second exciter (15) with respect to the first exciter; Filter characteristics and / or
Alternatively, the gain is configured such that the feature point is smoothed when the first and second exciters (13, 15) are commonly driven, and the flexural wave loudspeaker is characterized in that: 2. The loudspeaker according to claim 1, wherein the known frequency is a coincidence frequency. 3. The first exciter (15) on the panel (11) at a distance substantially equal to a half wavelength of a bending wave in the panel at a known frequency.
A loudspeaker according to claim 1 or 2, characterized in that it is arranged at a distance from the exciter (13). 4. The exciter according to claim 1, wherein the first and second exciters are connected in phase, and the bending waves emitted from the exciters are in phase. A loudspeaker according to claim 1. 5. The loudspeaker according to claim 4, wherein said first and second exciters are connected between common terminals. 6. The panel has a first axis (35) and a second axis (37), and the second exciter (15) is arranged along the first axis (35). Any of the preceding claims, spaced apart from a first exciter (13), for smoothing coincidence frequency feature points associated with bending waves along the first axis (35). A loudspeaker according to claim 1. 7. A third exciter (17) wherein said third exciter (17) has a distance substantially equal to a half wavelength of said bending wave at a coincidence frequency along said second axis (37). The loudspeaker according to claim 6, characterized in that the loudspeaker is arranged at a distance from the first exciter (13). 8. A fourth exciter (19) is provided, wherein said first exciter (13), second exciter (15), third exciter (17) and fourth exciter (19) are provided. Exciter (
The loudspeaker according to claim 7, wherein the (19) is arranged in a rectangular shape on the panel surface. 9. The second exciter (15) is arranged adjacent to the first exciter (13), and is connected in anti-phase with the first exciter (13). The loudspeaker according to claim 1 or 2, wherein 10. A filter is provided in association with one of said first and second exciters for selectively passing frequencies in a predetermined frequency band near a known frequency through said associated exciter. A loudspeaker according to any one of the preceding claims, characterized in that: 11. A loudspeaker according to claim 10, wherein said filter is a bandpass filter (81) connected in series with said associated exciter. 12. A high-frequency exciter (21) for exciting a frequency higher than a predetermined cut-off frequency, and a frequency higher than the cut-off frequency is supplied to the high-frequency exciter (21). Frequency to another exciter (13
Loudspeaker according to any one of the preceding claims, further comprising a crossover circuit (20) for supplying to the loudspeaker. 13. A panel (11) capable of supporting a bending wave, and first and second exciters mounted on the panel (11) for causing the bending wave in the panel to generate an acoustic output. Wherein the first and second exciters (13, 15) are spaced apart by a half-wavelength at a predetermined frequency, and the first and second exciters are provided. The loudspeaker wherein the sound output of the panel is affected at the predetermined frequency when the common drive is performed. 14. The loudspeaker according to claim 13, wherein the first and second exciters (13, 15) are connected in anti-phase to enhance the sound output at the predetermined frequency. 15. The first and second exciters (13, 15) are connected in phase to reduce the sound output at the predetermined frequency.
A loudspeaker according to claim 1. 16. The loudspeaker according to claim 15, wherein the known frequency is a coincidence frequency. 17. The exciter according to claim 15, wherein the first and second exciters are connected in phase, and the bending waves emitted from the exciters are in phase. Loudspeaker. 18. The loudspeaker according to claim 17, wherein the first and second exciters are connected between common terminals. 19. The panel has a first axis (35) and a second axis (37), and the second exciter (15) is arranged along the first axis (35). 16. A coincidence frequency feature point associated with a bending wave along the first axis (35), spaced from a first exciter (13), for smoothing.
20. The loudspeaker according to any one of claims 18 to 18. 20. A third exciter (17) substantially corresponding to said second shaft (37).
Characterized in that it is spaced from the first exciter (13) along the second axis (37) by a distance equal to half the wavelength of the bending wave at the coincidence frequency associated with A loudspeaker according to claim 19, wherein 21. A fourth exciter (19) is provided, wherein the first exciter (13), the second exciter (15), the third exciter (17) and the fourth exciter (19) are provided. 3. The exciter (19) is arranged in a rectangle on the panel surface.
A loudspeaker according to 0. 22. A filter associated with one of said first and second exciters (
The loudspeaker according to any one of claims 13 to 21, further comprising: 81) selectively passing frequencies in a predetermined frequency band near a known frequency through the associated exciter. . 23. A high-frequency exciter (21) for exciting a frequency higher than a predetermined cut-off frequency, and a frequency higher than the cut-off frequency is supplied to the high-frequency exciter (21). Frequency of another exciter (
23. A loudspeaker according to any one of claims 13 to 22, further comprising a crossover circuit (20) for supplying to the loudspeaker (13, 15, 17, 19). 24. A method for suppressing a characteristic point in a frequency response of a bending wave loudspeaker having a panel (11) capable of supporting a bending wave and a first exciter (13) mounted on the panel. Determining the frequency at which the response of the first exciter on the panel has a feature point; and wherein the first and second exciters (13, 15) are commonly driven. Providing a second exciter on the panel to smooth the feature points. 25. The method of claim 24, wherein the second exciter is located at a known frequency at a half wavelength of the bending wave in the panel. 26. The method of claim 24 or 25, wherein the step of determining a frequency determines the coincidence frequency associated with a predetermined direction.