HK1175626B - Audio system and television - Google Patents

Abstract

An audio system including a left input channel signal, a right input channel signal, and a discrete center input channel. Circuitry removes correlated content from the left input channel signal and the right input channel signal and inserts the correlated content into the center input channel signal to provide a modified left input channel signal, a modified right input channel signal, and a modified center input channel signal. The modified left input channel signal is radiated by a directional loudspeaker so that radiation in a direction toward a listening area is less than radiation in other directions. The modified right channel input channel signal is radiated by a directional loudspeaker so that radiation in a direction toward a listening area is less than radiation in other directions.

Description

Audio system and television

Technical Field

This specification describes an audio system.

Disclosure of Invention

In one aspect, an audio system includes a left input channel audio signal, a right input channel audio signal, and a separate center input channel audio signal; circuitry for removing correlated content from the left input channel audio signal and the right input channel audio signal and inserting the correlated content into the center channel signal to provide a modified left input channel audio signal, a modified right input channel audio signal, and a modified center input channel audio signal; a first directional loudspeaker for directionally radiating the modified left audio channel signal such that radiation in a direction toward a listening position is less than radiation in other directions; a second directional loudspeaker for directionally radiating the modified right channel audio signal such that radiation in a direction toward the listening position is less than radiation in other directions; and a third speaker for radiating the modified center channel. The first directional loudspeaker may include a first array of interferers. The second directional loudspeaker may include a second interference array. The second directional loudspeaker may comprise at least one common acoustic driver. The third speaker may be a third directional speaker for directionally radiating the modified center channel audio signal such that radiation in a direction toward the listening position is less than radiation in other directions. The third speaker may be a third directional speaker for directionally radiating the modified center channel audio signal such that radiation in a direction toward the listening position is greater than radiation in other directions. The third directional loudspeaker may comprise an interference array. The first directional speaker may include a first array of interferers; the second directional loudspeaker may comprise a second interference array; and the third directional loudspeaker may comprise a third interference array; and the first and third jamming arrays may comprise a common acoustic driver, and the second and third jamming arrays may comprise a common acoustic driver. The audio system may also include an acoustically opaque barrier between the third directional speaker and the listening position. The audio system may thus be implemented in a television set. The audio system may be mounted in a television set and the third loudspeaker may be a third directional loudspeaker for directionally radiating the modified center channel audio signal such that radiation in a direction toward the listening position is less than radiation in other directions. The audio system may be mounted in a television set and the third loudspeaker may be a third directional loudspeaker for directionally radiating the modified center channel audio signal such that radiation in a direction toward the listening position is greater than radiation in other directions. The third directional loudspeaker may comprise an interference array.

In another aspect, a method includes receiving a left channel audio signal, a right channel audio signal, and a separate center channel audio signal; removing correlated content from the left channel audio signal and the right channel audio signal to provide a modified left channel audio signal and a modified right channel audio signal; combining the related content with the discrete center channel audio signal; the modified left channel audio signal and the modified right channel audio signal are radiated directionally such that radiation is less toward a listening position than in other directions. Radiating the modified left channel audio signal may include radiating with a first interfering array, and radiating the modified right channel audio signal may include radiating with a second interfering array. The first jamming array and the jamming array comprise a common acoustic driver.

In another aspect, an audio signal circuit includes circuitry for removing correlated content from a left channel audio signal and a right channel audio signal to provide a modified left channel audio signal and a modified right channel audio signal; circuitry for combining the related content with a discrete center channel audio signal to provide a modified discrete center channel; and first processing circuitry for processing the modified left channel audio signal such that the modified left channel audio signal is directable radiatable by the first interference array; and second processing circuitry for processing the modified right channel audio signal such that the modified right channel audio signal is directionally radiable by the second array of interferers. The first processing circuit may process the modified left channel audio signal and the second processing circuit may modify the right channel audio signal such that the first jammer array and the jammer array comprise a common acoustic driver. The audio signal processing circuit may further include a third processing circuit for processing the modified discrete center channel such that the modified discrete center channel is directionally radiated by the interfering array. The third circuitry may process the modified discrete center channel such that the third directional array and the first directional array have a common acoustic driver, and such that the third directional array and the second directional array have a common acoustic driver.

Other features, objects, and advantages will become apparent from the following detailed description when read in conjunction with the following drawings, in which:

drawings

Fig. 1 is a schematic top view and a schematic front view of an audio module;

fig. 2 is a schematic top view, a schematic front view and a schematic side view of a television set comprising the audio module of fig. 1;

FIGS. 3A and 3B are schematic side views of one or more acoustic drivers for displaying an audio module;

3C-3E are schematic front views of an end acoustic driver of an audio module;

FIGS. 4A-4D are each a schematic diagram of an audio module showing the configuration of one of the directional arrays; and

fig. 5 is a block diagram of an audio signal processing system.

Detailed Description

Although elements of the various views of the drawings may be shown and described as discrete elements in a block diagram and may be referred to as "circuitry," these elements may be implemented as one or a combination of analog circuitry, digital circuitry, or one or more microprocessors for executing software instructions, unless otherwise indicated. The software instructions may include Digital Signal Processing (DSP) instructions. The operations may be performed by analog circuitry or by a microprocessor running software equivalent to the arithmetic or logic used to perform the analog operations. If not otherwise indicated, the signal lines may be implemented as separate analog or digital signal lines, as a single separate digital signal line with appropriate signal processing to process separate streams of audio signals, or as elements of a wireless communication system. Some of the processing may be described in block diagrams. The actions performed in each block may be performed by one element or by multiple elements, and may be separated in time. The elements used to perform the acts of the blocks may be physically separate. If not otherwise indicated, the audio signal or the video signal or both may be encoded and transmitted in digital or analog form, and conventional digital-to-analog and analog-to-digital converters may not be shown in the figures. For simplicity, the phrase "radiating acoustic energy corresponding to an audio signal in channel x" will be referred to as "radiating channel x".

Fig. 1 shows a top view and a front view of an audio module 12 comprising a plurality (in this embodiment, 7) of acoustic drivers 18-1 through 18-7. An acoustic driver 18-4 is located near the lateral center of the module, near the top of the audio module. The three acoustic drivers 18-1 to 18-3 are arranged close to the left end 20 of the audio module and are closely and unevenly spaced such that the distances l1 ≠ l2, l2 ≠ l3, l1 ≠ l 3. In addition, the interval is arranged such that l1 < l2 < l 3. Similarly, the distance l6 ≠ l5, l5 ≠ l4, l6 ≠ 4. In addition, the interval may be arranged such that l6 < l5 < l 4. In one implementation, l 1-l 6-55 mm, l 2-l 5-110 mm, and l 3-l 4-255 mm. The device of fig. 1 may be a stand-alone audio device or may be implemented in a television set, as shown below. Directional indicator 16 shows the intended orientation of audio module 12 in use. While the concepts disclosed herein are illustrated with the audio module of fig. 1, the principles may be implemented with other forms of directional speakers and in other configurations.

The audio module 12 of fig. 1 is particularly beneficial when used with or integrated into a television or similar media device. Fig. 2 shows a top view, a side view, and a front view of a television 10 including the audio module 12 of fig. 1 in a television console. The audio module is substantially linear and extends horizontally across the television above the screen. In other implementations, the audio module may be disposed below the screen. Further details of the audio module are shown in the following figures. The listener 14 is shown in a top view, the listener 14 showing the orientation of the television together with the directional indicator 16.

Figures 3A-3E show some variations in the orientation of one or more acoustic drivers 18-1 through 18-7. In the side view of fig. 3A, acoustic drivers 18-n (where n-1-7) are emitting upward, i.e., the radiating surfaces face upward. In the side view of FIG. 3B, acoustic driver 18-n is oriented such that the radiating surface faces upward and rearward at an angle θ relative to vertical, where θ is greater than 0 degrees and less than 90 degrees. In the front view of fig. 3C, the acoustic driver 18-1 closest to the left end of the audio module 12 is oriented substantially directly upward. In the front view of fig. 3D, the acoustic driver 18-1 closest to the left end of the audio module 12 is oriented facing upward and outward at an angle λ relative to vertical. In fig. 3E, the angle λ of the acoustic driver 18-1 is 90 degrees, so that the acoustic driver is emitting laterally, i.e., facing sideways. The mirror image of figures 3D and 3E may be used with acoustic driver 18-7. The orientation of figure 3D may be implemented with acoustic driver 18-2 or acoustic driver 18-3 or both. The mirror of figure 3D may be implemented with acoustic driver 18-5 or acoustic driver 18-6 or both. The one or more acoustic drivers may be in a combined orientation of the orientations of fig. 3A-E; for example, the acoustic drivers may be angled backwards and outwards with respect to the vertical. In one implementation, acoustic drivers 18-2 through 18-6 may be angled back such that angle θ is 27 ± 5% degrees, and acoustic drivers 18-1 and 18-7 are replaced by directional speakers (speakers configured such that radiation is substantially lateral as described in U.S. patent publication 2009/0274329a 1).

Orienting the acoustic driver according to fig. 3A-3E together with the signal processing described below results in more or all of the acoustic radiation reaching the listener being indirect radiation compared to the situation with a conventional audio system. A larger proportion of the acoustic radiation is indirect radiation resulting in a broad acoustic image as desired.

It is achieved by forming an interference-type directional array consisting of a subset of acoustic drivers 18-1 to 18-7 that causes as much of the acoustic radiation experienced by the listener as possible to be indirect radiation. Interference-type directional arrays are discussed in U.S. Pat. No. 5,870,484 and U.S. Pat. No. 5,809,153. At frequencies where the individual acoustic drivers radiate substantially omnidirectionally (e.g., frequencies where the corresponding wavelength is greater than twice the diameter of the radiating surface of the acoustic driver), the radiation from each acoustic driver interferes destructively or non-destructively with the radiation from each other acoustic driver. The combined effect of destructive and non-destructive interference is that the radiation in some directions is significantly less, for example-14 dB, relative to the maximum radiation in any direction. The direction in which the radiation is significantly less than the maximum radiation in any direction will be referred to as the "null direction". The effect of causing more of the radiation experienced by the listener to be indirect radiation is achieved by causing the direction between the audio module and the listener to be an empty direction.

At frequencies where the corresponding wavelength is less than twice the diameter of the radiating surface of the acoustic driver, the radiation pattern becomes less omnidirectional and more directional until at frequencies where the corresponding wavelength is equal to or less than the diameter of the radiating surface of the acoustic driver, the radiation pattern of the individual driver becomes inherently directional. At these frequencies, there is less destructive and non-destructive interference between the acoustic drivers of the array, and the acoustic image tends to collapse (collapse) into a single acoustic driver. However, if the acoustic driver is oriented according to fig. 3A-3E, the listener experiences indirect radiation even at frequencies corresponding to wavelengths equal to or less than the diameter of the radiating surface. As a result, the perceived source is diffuse and differs from the acoustic driver in some places. In addition, the barrier 21 deflects the radiation so that it reaches the listener indirectly. The barrier has the additional advantage of hiding the acoustic drivers and protecting them from damage from the front of the television set.

Fig. 4A shows a schematic diagram of audio module 12 showing the configuration of the directional array of audio modules. The audio module is used to radiate the channels of a multichannel audio signal source 22. Generally, a multi-channel audio signal source for use with a television set has at least a left (L), right (R), and center (C) channel. In FIG. 4A, left channel array 32 includes acoustic drivers 18-1, 18-2, 18-3, 18-4, and 18-5. The acoustic drivers 18-1 through 18-5 are coupled to the left channel signal source 38 by signal processor circuits 24-1 through 24-5, respectively, the signal processor circuits 24-1 through 24-5 applying transfer functions H, respectively_1L(z)-H_5L(z) signal processing. Transfer function H_1L(z)-H_5LThe (z) effect on the left channel audio signal may include one or more of phase shift, time delay, polarity inversion, etc. Transfer function H is generally_1L(z)-H_5L(z) is implemented as a digital filter, but can be implemented with equivalent analog devices.

In operation, the transfer function H will be determined by the acoustic drivers 18-1 through 18-5_1L(z)-H_5L(z) the modified left channel signal L is converted into acoustic energy. Radiation from the acoustic driver interferes destructively and non-destructively to result in the desired directional radiation pattern. To achieve a wide stereo image, the left array 32 directs radiation toward the boundary of the space as indicated by arrow 13 and cancels out towards the listenerOf (2) is performed. For example, Boone et al describes in design of high direction oriented end speaker array in volume 57 of audio eng.soc. the use of digital filters to apply transfer functions to create a directional interference array. This concept is also discussed by design logic microphone minor space directive-directive transmission radrrays (also with respect to the loudspeaker) in volume 44 of audio eng.soc. of 1996, by van der wal et al, and by the analysis design sound base and sensory acquisition radar with frequency in microphone patterns, by Ward et al, 2.1995, j.acout.soc.am.97 (2). Arithmetically, the directional microphone array concept can be generally applied to a speaker.

Similarly, in FIG. 4B, right channel array 34 includes acoustic drivers 18-3, 18-4, 18-5, 18-6, and 18-7. The acoustic drivers 18-3 through 18-7 are coupled to the right channel signal source 40 by signal processor circuits 24-3 through 24-7, respectively, the signal processor circuits 24-3 through 24-7 applying transfer functions H, respectively_3R(z)-H_7R(z) signal processing. Transfer function H_3R(z)-H_7RThe influence of (z) may include one or more of phase shift, time delay, polarity inversion, etc. Transfer function H is generally_3R(z)-H_7R(z) is implemented as a digital filter, but can be implemented with equivalent analog devices.

In operation, the transfer function H will be determined by the acoustic drivers 18-3 through 18-7_3R(z)-H_7R(z) the modified left channel signal L is converted into acoustic energy. Radiation from the acoustic driver interferes destructively and non-destructively to result in the desired directional radiation pattern. To achieve a wide stereo image, the right array 34 directs radiation towards the right boundary of the space as indicated by arrow 15 and cancels radiation towards the listener.

In FIG. 4C, center channel array 36 includes acoustic drivers 18-2, 18-3, 18-4, 18-5, and 18-6. The acoustic drivers 18-2 through 18-6 are coupled to the center channel signal source 42 by signal processor circuits 24-2 through 24-6, respectively, the signal processor circuits 24-2 through 24-6 applying transfer functions H, respectively_2C(z)-H_6C(z) isAnd (6) signal processing. Transfer function H_2C(z)-H_6CThe influence of (z) may include one or more of phase shift, time delay, polarity inversion, etc. Transfer function H is generally_2C(z)-H_6C(z) is implemented as a digital filter, but can be implemented with equivalent analog devices.

In operation, the transfer function H will be determined by the acoustic drivers 18-2 through 18-6_2C(z)-H_6C(z) the modified center channel signal C is converted to acoustic energy. Radiation from the acoustic driver interferes destructively and non-destructively to result in the desired directional radiation pattern.

An alternative configuration for the center channel array is shown in fig. 4D, where center channel array 36 includes acoustic drivers 18-1, 18-3, 18-4, 18-5, and 18-7. The acoustic drivers 18-1, 18-3-18-5, and 18-7 are coupled to the center channel signal source 42 by signal processor circuits 24-1, 24-3, 24-5, and 24-7, respectively, which signal processor circuits 24-1, 24-3, 24-5, and 24-7 apply a transfer function H, respectively_1C(z)、H_3C(z)-H_5C(z) and H_7C(z) signal processing. Transfer function H_1C(z)、H_3C(z)-H_5C(z) and H_7CThe influence of (z) may include one or more of phase shift, time delay, polarity inversion, etc. Transfer function H is generally_1C(z)、H_3C(z)-H_5C(z) and H_7C(z) is implemented as a digital filter, but can be implemented with equivalent analog devices.

In operation, the transfer function H will be determined by acoustic drivers 18-1, 18-3-18-5, and 18-7_1C(z)、H_3C(z)-H_5C(z) and H_7C(z) the modified left channel signal C is converted into acoustic energy. Radiation from the acoustic driver interferes destructively and non-destructively to result in the desired directional radiation pattern.

The center channel arrays of fig. 4C and 4D direct radiation upward and rearward as indicated by arrow 17 and cancel radiation toward the listener.

At high frequencies (e.g., frequencies where the corresponding wavelength is less than three times the distance between array elements), the stereo acoustic image may tend to "collapse" towards the more closely spaced acoustic drivers of the array. If the array elements of the directional array at the center of the array are more closely spaced than the array elements at the ends (e.g., "nested harmonic" directional arrays or logarithmically spaced arrays, such as described in the above-mentioned vanderWal article), the stereo imagery will collapse toward the center of the array.

One way to prevent collapse toward the center of the array is to form 3 arrays, one array with closely spaced elements adjacent the left end of the acoustic module, one in the center of the acoustic module, and one at the right end of the acoustic module. However, this solution requires many acoustic drivers and is therefore expensive. For example, forming a five element left, center and right channel array would require 15 acoustic drivers.

The acoustic module according to fig. 4A-D allows left, center and right arrays with fewer acoustic drivers and greatly reduces the amount of collapse of the acoustic image towards the center of the array. Since collapse tends towards more closely spaced elements, to the left end of the acoustic module 12 if there is any collapse of the left channel, and to the right end of the acoustic module 12, as opposed to towards the middle of the acoustic image, if there is any collapse of the right channel, as would be the case if the more closely spaced acoustic drivers were near the lateral middle of the acoustic module. In addition, the audio system according to fig. 4A-4D provides a wider portion of the listening area receiving indirect radiation and thus has a more diffuse, happy stereo image than an audio system having a directional array at the lateral middle of the television screen.

In some cases, causing the acoustic radiation experienced by the listener to be indirect radiation may cause the acoustic image to be different than when radiated by a conventional speaker system where the majority of the radiation experienced by the user is direct radiation. For example, some music videos are mixed so that the voice image of the singer is concentrated but more diffused than the voice image of the actor speaking in the reproduction of the moving image. One method for creating the audio image is to insert some singer's channels into the left and right channels. The insertion of the singer's channel in the left and right channels may have the desired effect of creating a diffuse, concentrated sound image when reproduced on a conventional stereo or 5.1 channel reproduction system. However, when reproduced on the reproduction system according to fig. 1-4D, the singer's voice image is more diffuse than when reproduced on the conventional stereo of the 5.1 channel reproduction system.

Fig. 5 shows the audio processing system of fig. 4A-4D with additional elements. The channel modifier 122 couples the multi-channel audio signal source 22 to the directional arrays 32, 34 and 36. The channel modifier 122 includes a correlation determiner 100 and a signal combiner 102. The left channel signal represented by line 138 and the right channel signal represented by line 140 are coupled to the correlation determiner 100. The correlation determiner 100 is coupled to the modified left channel signal source 38 ', to the modified right channel signal source 40' and to the combiner 102. The separate center channel signals, represented by lines 142, are coupled to the signal combiner 102. The signal combiner 102 is coupled to the modified center channel signal source 42'. As shown in fig. 4A-4D, a modified left channel signal source 38 ', a modified right channel signal source 40 ' and a modified center channel signal source 42 ' are coupled to the left channel array 42, the right channel array 34 and the center channel array 36, respectively.

In operation, the correlation determiner 100 removes correlated content in the left channel audio signal represented by line 138 and in the right channel audio signal represented by line 140 and combines the removed correlated content from the left and right channel audio signals with the center channel audio signal represented by line 142. The modified left channel audio signal, the modified right channel audio signal and the modified center channel audio signal are then processed as described above.

The correlation determiner 100 and the signal combiner 102 may be implemented by analog circuitry, but most conveniently by one or more digital signal processors for executing digital signal processing instructions. The digital signal processor may also implement the transfer functions of fig. 4A-4D.

The elements of fig. 5 are described as being implemented in an audio system as described in fig. 1-4D. The elements of fig. 5 may be advantageously implemented in any multi-channel audio system with a separate center channel and this results in more radiation reaching the listener indirectly rather than directly.

In an alternative embodiment, the speakers may be configured, oriented and arranged and the transfer functions may be selected such that the center channel array 38 of fig. 4C and 4D directs radiation toward the listener.

The audio processing system of fig. 5 may advantageously be combined with the audio system described in us patent application 12/465,146. In the above case, the relevant content removed from the left and right channels may be combined with the music center channel, as described in U.S. patent application 12/465,146.

Numerous uses of departures from the specific apparatus and techniques disclosed herein may be made without departing from the inventive concepts. The invention is therefore to be construed as embracing each and every novel feature and novel combination of features disclosed herein and limited only by the spirit and scope of the appended claims.

Claims (15)

1. An audio system, comprising:

at least three acoustic drivers arranged substantially in a line and separated by non-uniform distances;

a first interference directional array comprising:

a first subset of the at least three acoustic drivers for directionally radiating one of a left channel audio signal and a right channel audio signal; and

signal processing circuitry to process audio signals to a first subset of the acoustic drivers such that radiation from each of the acoustic drivers destructively interferes such that radiation in a direction toward a listening position is less than radiation in other directions;

a second interference directional array comprising:

a second subset of the at least three acoustic drivers for directionally radiating the other of the left channel audio signal and the right channel audio signal; and

signal processing circuitry for processing audio signals to a second subset of the acoustic drivers such that radiation from each of the acoustic drivers destructively interferes such that radiation in a direction towards a listening position is less than radiation in other directions;

the first subset and the second subset include at least one common acoustic driver.

2. The audio system of claim 1, wherein a distance between two leftmost acoustic drivers in the first disturbing directional array is less than a distance between any other two acoustic drivers in the first disturbing directional array, and wherein a distance between two rightmost acoustic drivers in the second disturbing directional array is less than a distance between any other two acoustic drivers in the second disturbing directional array.

3. The audio system of claim 1, wherein the radiating surface of the acoustic driver faces upward.

4. The audio system of claim 3, wherein the radiating surface of the acoustic driver faces upward and rearward.

5. The audio system of claim 1, wherein a radiating surface of the leftmost acoustic driver faces outward.

6. The audio system of claim 1, further comprising an opaque acoustic barrier in front of the acoustic driver.

7. The audio system of claim 1 implemented in a television set.

8. The audio system of claim 1, further comprising:

a third interference directional array comprising:

a third subset of the at least three acoustic drivers for directionally radiating a center channel audio signal; and

signal processing circuitry to process audio signals to a third subset of the acoustic drivers such that radiation from each of the acoustic drivers destructively interferes such that radiation in one direction is less than radiation in other directions.

9. A television set comprising an audio device, the audio device comprising:

at least three acoustic drivers arranged substantially in a line and separated by non-uniform distances;

a first interference directional array comprising:

a first subset of the at least three acoustic drivers for directionally radiating one of a left channel audio signal and a right channel audio signal; and

signal processing circuitry to process audio signals to a first subset of the acoustic drivers such that radiation from each of the acoustic drivers destructively interferes such that radiation in a direction toward a listening position is less than radiation in other directions;

a second interference directional array comprising:

a second subset of the at least three acoustic drivers for directionally radiating the other of the left channel audio signal and the right channel audio signal; and

signal processing circuitry for processing audio signals to a second subset of the acoustic drivers such that radiation from each of the acoustic drivers destructively interferes such that radiation in a direction towards a listening position is less than radiation in other directions;

the first subset and the second subset include at least one common acoustic driver.

10. The television set of claim 9, wherein a distance between two leftmost acoustic drivers in the first array of disturbing orientations is less than a distance between any other two acoustic drivers in the first array of disturbing orientations, and wherein a distance between two rightmost acoustic drivers in the second array of disturbing orientations is less than a distance between any other two acoustic drivers in the second array of disturbing orientations.

11. The television of claim 9, wherein the radiating surface of the acoustic driver faces upward.

12. The television set as described in claim 11, wherein the radiating surface of the acoustic driver faces upward and rearward.

13. The television of claim 9, wherein the radiating surface of the leftmost acoustic driver faces outward.

14. The television set of claim 9, further comprising an opaque acoustic barrier in front of the acoustic driver.

15. The television set of claim 9, further comprising:

a third interference directional array comprising:

a third subset of the at least three acoustic drivers for directionally radiating a center channel audio signal; and

signal processing circuitry is to process the audio signals to the third subset of acoustic drivers such that radiation from each of the acoustic drivers destructively interferes such that radiation in one direction is less than radiation in the other direction.