CN101536541A - Apparatus for reproduction of stereo sound - Google Patents

Abstract

Apparatus for reproducing stereo sound having a housing (1, 25) defining an at least partially enclosed space. A first transducer (7) or pair of transducers (28, 29) is provided and arranged to reproduce one, both or the sum of two audio signals. A pair of transducers (10, 32) is also provided and arranged to reproduce a signal comprising the difference of the two audio signals. All the transducers communicate with the at least partially enclosed space, and the transducers arranged to reproduce the difference between the two audio signals are each arranged to direct their output primarily in a direction generally at right angles to the direction in which the first transducer or pair of transducers primarily direct their output. The apparatus may be arranged to be placed on or adjacent a generally flat surface, and the transducers arranged to reproduce the difference of the two audio signals may be arranged to direct their output towards the flat surface.

Description

equipment for reproducing stereo sound

technical field

The present invention relates to a device for reproducing stereophonic sound, and more particularly to a device for reproducing stereophonic sound from a two-channel stereophonic signal.

Background technique

Stereo recording and reproduction utilizes stereo projection to encode the relative positions of recorded sound sources and aims to reproduce sounds by sensing these relative positions. Stereo systems can contain two or more channels, but binaural systems reign supreme when it comes to audio recording. Two channels (often referred to as left and right channels) carry information about the sound field in front of the listener. By far the most popular means for reproducing a two-channel stereo signal is to play the channels separately through spatially separated left and right speakers.

Although very popular, this system still has disadvantages. Most commercial binaural recordings are made for optimal reproduction by speakers spatially separated by about 1.6 meters. In practice, this is unlikely, especially if one wants to reproduce stereo sound from a single unit. In any case, regardless of how the recording was recorded, the closer the speakers used to send the left and right channels, the worse the stereo reproduction will be.

Moreover, for the most perfect stereo effect, the listener should be located at the apex of an equilateral triangle formed by a pair of speakers and the listener. But in practice, it is usually inconvenient or impossible for a listener to adopt or maintain this position, and of course, it is even more impossible for multiple listeners to listen from the same position.

Alternative systems for reproducing two-channel stereo signals should overcome some of the above-mentioned disadvantages. In US 3,588,355 is disclosed what should be called a "sum and difference system". This document discloses a stereo speaker system comprising two pairs of speakers. The speakers of each pair are oriented so that their axes are perpendicular to each other, and the speakers are substantially equidistant from the intersection of the axes. The speakers are arranged so that one speaker of each pair faces the listener, and the axis of the other speaker is oriented substantially at right angles to the direction of the listener. An apparatus is provided for matrixing left and right two-channel stereophonic signals to provide sum and difference signals. The sum signal is applied in phase to the loudspeaker whose axis is directed towards the listener, and the difference signal is applied to the loudspeaker whose axis is perpendicular to the direction of the listener, the difference signals applied to the two perpendicularly positioned loudspeakers being 180° out of phase with each other. As a result, the system will generate a stereo effect.

While the problems associated with the use of spatially separated loudspeakers would be overcome, the arrangement of US3,588,355 has not been widely used. This is believed to be due to implementation difficulties of the disclosed device, which would result in an actual sound quality obtained and a perceived stereophonic effect that is worse than theoretically expected.

Contents of the invention

The present invention seeks to provide an improved device for reproducing stereophonic sound.

According to a first aspect of the present invention there is provided a device for reproducing stereophonic sound comprising a first transducer arranged to reproduce one of two audio signals and a first transducer arranged to reproduce the other A second transducer of a signal, the device further comprising one or two transducers arranged to reproduce a signal comprising the difference of said two audio signals.

This arrangement combines the advantages of a conventional two-speaker system for reproduction of stereo sound with the advantages of a sum-and-difference system. A properly oriented difference signal can be used to enhance the perceived width and depth of the reproduced signal. This is useful where the perceived width and depth of the signal reproduced by the first and second transducers alone is limited. This is the case where two transducers are arranged in close proximity, for example both transducers are located in the same housing in portable stereo reproduction equipment.

The device may include a housing defining an at least partially enclosed space. All transducers can be mounted in the housing and can all communicate with the partially enclosed space. The first and second transducers are preferably arranged to direct their outputs in substantially parallel, spatially separated directions. The two transducers arranged to reproduce the difference of the two signals are preferably arranged to direct their outputs substantially in the same direction as said first transducer and the second transducer are arranged to direct their outputs substantially The pointed direction is substantially at right angles to the direction and may have its output in a substantially opposite direction.

According to a second aspect of the present invention there is provided a device for reproducing stereophonic sound, the device comprising a housing defining an at least partially enclosed space, arranged to generate one of two audio signals or two a first transducer of the sum of the audio signals, and two transducers, each of which is arranged to reproduce a signal comprising the difference of said two audio signals, wherein said three transducers are all in communication with said at least partially enclosed space, and wherein each of said transducers arranged to reproduce a signal comprising the difference of said two audio signals is arranged to have its own output substantially Pointing up is substantially at right angles to the direction in which the first transducer is arranged to point its output substantially.

The first transducer is arranged to reproduce one of the two audio signals, a second transducer is preferably provided to reproduce the other signal, and the first and second transducers are preferably arranged to reproduce themselves The outputs of are directed in substantially parallel, spatially separated directions.

Stereo reproduction and difference systems are generally thought to work by modifying the playback audio and signal by varying amounts at different locations from the playback difference signal to recreate the originally recorded sound field, or an approximation of that sound field. Where the first and second transducers are provided to send audio signals separately, playing the sum of the two signals by one or more transducers will have a similar effect, especially if the two transducers are in close proximity hour. Having all three transducers (or possibly four as the case may be) communicate with the same partially enclosed space has two distinct benefits. First, this simplifies the mechanical construction of the device (particularly the housing), eliminating the need to construct isolators or valves to separate the transducers. This can reduce the overall size of the housing required for a given transducer, and/or can allow other components to be mounted in the housing. Likewise, this would enable a pair of loudspeakers arranged to transmit a difference signal to be incorporated into the available space within the enclosure of an existing mono or stereo device, thereby, without increasing the size of the enclosure, Enables equipment to be redesigned to reproduce stereo or improved stereo audio signals. Second, this increases the interaction between the outputs of the transducers which can add increased perceived depth and width to the sound reproduced by the device.

According to a third aspect of the present invention there is provided a device for reproducing stereophonic sound, the device comprising a housing arranged to be placed on or adjacent to a substantially flat surface, arranged to generate two audio a first transducer of one of the audio signals or the sum of the two audio signals, and two transducers, each of which is arranged to reproduce the audio signal comprising the two audio signals difference signal, wherein each of said transducers arranged to reproduce a signal comprising the difference of said two audio signals is arranged such that the output mainly in a direction generally at the right corner becomes the first transducer The transducer is arranged such that its output is mainly located in a direction, and wherein said transducer arranged to reproduce a signal comprising the difference of said two audio signals is arranged relative to the outer box such that when the outer casing is When placed on or adjacent to a substantially flat surface, both transducers are oriented such that their outputs are primarily in a direction extending toward the plane of the surface.

By orienting the output of the transducer reproducing the difference signal toward the surface against which the device is used, any surface-induced surface effects that are normally found to improve the output of the device are enhanced.

The first transducer is arranged to reproduce one of the two audio signals, a second transducer is preferably provided to reproduce the other signal, and the first and second transducers are preferably arranged to combine their own The outputs are directed in substantially parallel, spatially separated directions.

A device according to any aspect of the invention may include any or all of the additional features of another aspect of the invention, as appropriate.

The following relate to optional features of all aspects of the invention.

Each transducer may be a microphone. The loudspeaker may comprise a driver arranged to drive a loudspeaker element, eg, wherein the loudspeaker element may be a diaphragm of any suitable shape, such as a frusto-conical shape or a substantially flat shape.

Said transducers arranged to reproduce a signal comprising the difference of said audio signal ("difference signal") are preferably arranged to reproduce signals substantially out of phase with each other and to orient the direction of the two out of phase signals in different directions (preferably substantially opposite directions). The out-of-phase signals are preferably 180 degrees out of phase.

The housing preferably has two openings through which the two difference signals are routed. The housing is arranged to be placed on or adjacent to a flat surface, preferably the opening is placed on the housing such that when the housing is placed on or adjacent to a flat surface, the opening is located adjacent to the surface . Preferably, the housing includes at least one substantially planar surface. This may form the bottom of the housing, allowing the housing to rest on a flat surface, or may form the sides of the housing, enabling the housing to be adjacent to a flat surface such as a wall. Alternatively or additionally, the housing may include one or more planar surfaces extending from adjacent the opening or adjacent each opening. The or each opening is arranged to be able to be located adjacent to the surface so that surface effects can be used. As discussed further below, arranging the difference signal to be played along a flat surface enhances the difference signal, and in turn enhances the overall perception of width and depth of the sound reproduced by the sum and difference system.

The housing may also comprise an opening through which a signal comprising the sum of the two provided audio signals may be transmitted. Alternatively, the housing includes one or two openings through which audio signals are respectively sent. The housing may also comprise further openings forming ports which act as pressure relief valves into the at least partially enclosed space when low frequencies are reproduced. The valve may lead to a conduit or tube extending in at least part of the enclosure formed by the housing. In addition to being provided with a valve, the housing may be completely enclosed.

The two transducers arranged to reproduce the difference signal are oriented to direct their output mainly in a direction extending towards the plane of the substantially flat surface or surface against which the housing is backed, preferably such that each transducer The direction of the transducer is towards the surface at an angle between 1° and 8°, more preferably between 2° and 6°, and even more preferably between 3° and 5°. The housing comprises a substantially planar surface, relative to which a transducer arranged to reproduce the difference signal, as described above, may be oriented relative to a plane corresponding substantially to any surface on which said transducer is placed or adjacent. The plane of a substantially flat surface.

The device may be used to reproduce a two-channel stereophonic signal using the sum-and-difference system. In this case, the transducer for reproducing the two out-of-phase difference signals is driven with a signal comprising or preferably only consisting of the difference of the two stereo channels, and with a signal comprising or preferably consisting only of the sum of the two stereo channels Drives the third transducer.

The device may include sum and difference matrices to achieve this.

Alternatively, the device may be used to reproduce a two-channel stereo signal using a conventional arrangement of two spatially separated transducers, each for one of the two stereo channels, supplemented with For transducers that reproduce two phase-difference signals, the two transducers are driven by a signal that consists of, and preferably consists of, only the difference of the two stereo channels.

In any case, the difference signal can be filtered to reduce the amplitude of low frequencies. Low frequencies included in the sum signal or a single channel of the stereo signal used to drive the two transducers may be boosted. The device may include a high pass filter and/or a bass boost compensation circuit. It has been found that boosting the low frequencies sent by the transducer that reproduces the sum or individual components of the two audio signals, and reducing or eliminating the low frequencies sent by the transducer that reproduces the difference signal, leads to a further improvement in the depth and perception of the reproduced sound . This is also discussed further below.

The device may be provided in a housing arranged to accommodate means that is to provide a stereo signal to drive the transducer. In particular, the device may be included in a docking station for an MP3 player or other portable music playback device. Alternatively, the apparatus may comprise means or related components for generating a stereo signal to drive the transducer, such as an audio tuner.

Description of drawings

For a clearer understanding of the present invention, embodiments of the present invention are now described by way of example with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a speaker unit according to the present invention;

Fig. 2 is a sectional view taken along the plane formed by a-a and b-b line of Fig. 1;

Fig. 3 is a sectional view taken along the plane formed by a-a and c-c lines of Fig. 1;

Figure 4 is a block diagram of circuitry associated with the unit of Figure 1;

5 is a front sectional view of another embodiment of the speaker unit according to the present invention;

Figure 6 is a side cross-sectional view of the embodiment of Figure 5;

Figure 7 is a block diagram of circuitry associated with the unit of Figure 5;

Fig. 8 is a schematic perspective view of a TV set incorporating a speaker unit according to the present invention;

Fig. 9 is a cross-sectional view of the television set of Fig. 8 placed against a wall, viewed from above.

Detailed ways

In the following, terms such as front, rear, top, bottom etc. are used to refer to a direction relative to the device shown or to be used. These terms are used for convenience only and should not be construed as limiting.

Referring to the drawings, Figures 1-4 show a sum-difference loudspeaker unit according to the present invention. The unit may incorporate means (not shown) for reproducing audio signals, eg a tuner, such as a DAB tuner, a compact disc player or an MP3 player.

The unit comprises a housing 1 whose exterior is generally cuboidal. The housing is manufactured from rigid board, but may be manufactured from any other suitable material, such as is commonly used to manufacture loudspeaker housings. A generally circular aperture (not shown) is formed in the front of the housing and is covered by a grille or other substantially sound permeable covering.

A substantially circular hole 3 is respectively formed in each of the two opposite side walls 4 of the housing 1, and each hole is covered by a grille 5 or other substantially sound-permeable covering. Each of said apertures is located approximately in the middle along the way, adjacent to the bottom edge of the side wall 4 forming the aperture.

Towards the rear of the bottom side 6 of the housing 1 there is also provided another substantially circular hole. The bottom side of the housing is substantially flat such that the housing can be supported by placing its bottom side on a substantially flat surface.

Holes are not formed on the top and rear of the housing.

A single speaker 7 is installed inside the front of the unit to fill a hole formed in the front of the unit. The loudspeaker is of conventional type and comprises a driver 8 arranged to drive a diaphragm 9 of generally frusto-conical shape. A speaker 7 is arranged to transmit audio signals through a hole in the front of the unit.

A single loudspeaker 10 is also mounted on the inside of each side wall 4 of the unit, filling the holes in the side walls. Each loudspeaker 10 also comprises a driver 8 and a diaphragm 9 of generally frusto-conical shape. Each loudspeaker 10 is mounted on the side wall at an angle relative to the side wall 4 such that the central axis of its diaphragm 9 (shown in phantom) extends towards the extension of the plane of the unit bottom side 6, while the axis is from the unit. extended outward. Each loudspeaker 10 was mounted so that the central axis of its diaphragm 9 would intersect the extension of the plane of the bottom side of the unit at an angle of about 4 degrees. Thus, the axes of the diaphragms of the two loudspeakers 10 mounted on the side wall 4 of the unit respectively cross each other at an angle of approximately 172 degrees.

In an alternative arrangement, each loudspeaker 10 may be mounted in a position close to, but spatially separated from, the inside of the side wall 4 of the enclosure 1 .

A cardboard tube 11 is mounted inside the unit bottom side 6, over a hole formed in the unit bottom side and protrudes into the unit. Tube 11 forms a valve. The valves and all three speakers share the same acoustic environment within the unit.

The speaker unit is associated with the electronic circuit shown in Figure 4. Preferably, the circuit components can be placed inside the casing 1 or placed separately. The circuit component may be placed in the housing together with other components, in particular components arranged to generate audio signals, such as a tuner.

The circuit comprises two inputs 14 , 15 connected to a sum-difference matrix transformation unit 16 . The sum-difference matrix transformation unit 16 is arranged to produce two outputs: a sum output at 17, which includes the sum (14+15) of the inputs at 14 and 15; and a difference output at 18, which The difference output comprises the difference of the inputs at 14 and 15 (14-15).

And the output terminal 18 is connected to the bass boost compensation circuit 19. This adds approximately 3dB of gain to the low frequency content of the signal, typically frequencies between 40 and 500 Hz. The output of the bass boost compensation circuit is connected via a power amplifier 20 to a speaker 7 ("mono speaker") mounted behind a hole in the front of the unit.

The difference output 18 is connected to a high pass filter 21 operable to reduce the amplitude for frequencies below 100 Hz by at least 3 dB. The filtered signal is then provided with a gain of about 4dB by amplifier 22, the output of which is connected via power amplifier 20 to loudspeaker 10 located behind aperture 3 in side 4 of the unit ("differential loudspeaker"). The outputs are connected to two difference speakers such that when driven by the difference signal, the signals generated by the two speakers are out of phase (ie out of phase).

The power amplifier 20 associated with the differential speaker 10 need only have about 10-20% of the power output associated with the mono speaker 7 .

The loudspeaker unit uses a sum-and-difference system to reproduce a traditional two-channel stereo signal. In use, the unit is preferably positioned on a flat surface 23 which extends in all directions towards the unit. The two channels (left and right) of the stereophonic signal are then supplied to the two inputs 14 and 15 of the sum-difference matrix transformation unit 16, respectively. Ideally, the listener should be located toward the front of the unit, but can also be located at the rear of the unit. While the unit enables the listener to appreciate the depth and width effects of a stereo recording over a wide area, the depth and width effects are at or near the axis extending through the mono speaker 7 (i.e. substantially perpendicular to the front of the enclosure 1). Part) the detection effect is the best. The depth and width effects are worst at positions lying on the axis extending through the duct difference loudspeaker 10 (ie substantially perpendicular to the side 4 of the housing 1).

The loudspeaker unit has significant advantages over conventional sum-and-difference loudspeakers. Enclosure 1 defines a single acoustic enclosure shared by all loudspeakers. This simplifies manufacturing and eliminates the need to partition the interior of the enclosure to provide a separate acoustic package, and provides more room within the enclosure for electronics and related components. Maximizing space utilization is important in the manufacture of compact devices. Having the three loudspeakers share the same acoustic package also improves the possible interaction between the outputs of the different loudspeakers. The air valve formed by the cardboard tube 11 and its associated hole acts as a pressure relief valve for low frequencies.

Placing the differential speakers adjacent to the bottom edges of the sides of the enclosure enables the use of surface effects when the enclosure is placed on a surface, for example the floor or the top of a piece of furniture. Placing speakers in this way takes advantage of surface effects. When sound is reproduced in close proximity to a flat surface (ideally, a flat surface with a linear dimension greater than the lowest frequency wavelength within the sound), sound reflections from the surface have the effect of intensifying the sound around the surface. In this way, the sound pressure level away from the sound source is reduced to a lower level compared to the theoretical inverse square law. In practice, the sound level of the difference signal transmitted through the difference loudspeaker 10 is increased by about 8-10 dB. This improves the effect of depth and width in the reproduced sound. Mounting the differential loudspeaker at an angle so that the loudspeaker is slightly facing the surface on which the unit rests further helps to take advantage of surface effects. Another benefit of placing the differential loudspeakers 10 at an angle is that since the loudspeakers do not share a common axis, the tendency to form mid-frequency standing waves within the enclosure is reduced. This is undesirable as it may impair the overall quality of the sound reproduced by the unit. Another advantage is that the differential speaker angles provide a guiding element to the primary spatial sound image generated by the device.

Performance improvements can also be obtained by processing incoming sound signals. The low frequency sound reproduced by the poor speaker 10 is relatively poor compared to the low frequency sound reproduced by the larger monaural speaker 7 . This is due in part to the inherently reduced ability of smaller speakers to reproduce low frequencies, and also to mutual cancellation between the out-of-phase signals produced by the two speakers, which is expected to occur at low frequencies due to their inherently long wavelengths. While the mutual cancellation problem could be reduced by further separating the two poor speakers, the required separation is impractical. Instead, the low frequencies reproduced by the poor speaker 10 are compensated by boosting the amplitude of the low frequencies in the sum signal driving the mono speaker 7 . This in turn enables low frequencies to be cut from the difference signal by high frequency filter 21 means, improving the integrity of the audio difference signal.

Figures 5-7 show alternative embodiments of loudspeaker units according to the invention. The unit is substantially similar to that shown in Figures 1-4, except that the single speaker 10 arranged to play the sum of two audio channels is replaced by two speakers arranged to play the individual audio channels respectively.

The embodiment of Figures 5-7 includes a housing 25 which is generally cuboidal in appearance. The housing is manufactured from rigid board, but may be manufactured from any other suitable material, such as is commonly used to manufacture loudspeaker housings. In the front (not shown) of the housing 25 are formed two generally circular holes (not shown) which are covered by a grill or other substantially sound permeable covering. A smaller, generally circular aperture 33 is formed in each of the two opposing side walls 26 of the housing 25, and each aperture is covered by a grille 34 or other substantially sound permeable covering. . Each of the apertures is located approximately midway along the way, adjacent to the bottom edge of the aperture-forming side wall 26 .

There is also a generally circular aperture towards the rear of the bottom side 27 of the housing 25 . The bottom side of the housing is substantially flat such that the housing can be supported by its bottom side on a substantially flat surface.

Holes are not formed on the top and rear of the housing.

Speakers 28, 29 are mounted inside the front of the unit to fill holes formed in the front of the unit. The loudspeaker is of conventional type and comprises a driver 30 arranged to drive a diaphragm 31 of generally frusto-conical shape. Loudspeakers 28, 29 are arranged to transmit audio signals respectively through holes in the front of the unit.

A single speaker 32 is also mounted on the inside of each side wall 26 of the unit, filling the hole in the side wall. Each loudspeaker 32 also includes a driver 30 and a diaphragm 31 of generally frusto-conical shape. In the same manner as the unit shown in FIG. 2 , each loudspeaker 32 is mounted on the side wall at an angle relative to the side wall 26 so that the central axis of its diaphragm extends towards the extension of the plane of the unit bottom side 27 , with the axis extending outward from the cell.

In an alternative arrangement, each loudspeaker 10 may be mounted in a position close to, but spatially separated from, the inside of the side wall 4 of the enclosure 1 .

A cardboard tube 35 fits inside the unit bottom side 27, over a hole formed in the unit bottom side and protrudes into the unit. The tube forms the valve. The valves and all four speakers share the same acoustic environment within the installation. The air valve formed by the cardboard tube 35 and its associated hole acts as a pressure relief valve for low frequencies.

The speaker unit is associated with the electronic circuit shown in FIG. 7 . The circuit assembly may preferably be housed within housing 26 or separately. The circuit component may be placed in the housing together with other components, in particular components arranged to generate audio signals, such as a tuner.

The circuit comprises two inputs 36,37. The input ends are respectively connected to speakers 28 and 29 through a bass boost compensation circuit 38 and a power amplifier 39 . Bass boost compensation circuit 38 adds approximately 3dB of gain to the low frequency content of the signal, typically frequencies between 40 and 500 Hz.

The two circuit inputs 36 and 37 are also connected to a subtraction circuit 40 which outputs the difference of the signals received at the inputs 36 and 37 . The difference output is connected to a high pass filter 41 operable to reduce the amplitude of frequencies below 100 Hz by at least 3 dB. The filtered signal is then provided with a gain of approximately 4dB by an amplifier 42 whose output is connected via a power amplifier 43 to the loudspeaker 30 located behind the aperture 3 in the side 4 of the unit ("differential loudspeaker"). The output is connected to the two difference speakers so that when the two difference speakers are driven by the difference signal, the signals generated by the two speakers are out of phase (ie anti-phase). More specifically, the differential speaker adjacent to speaker 28 is driven with a signal comprising a signal received at input 36 that is smaller than the signal it contains received at input 37, and the other differential speaker (due to its The opposite polarity) is also effectively driven with a signal that contains a signal received at input 37 that is smaller than the signal it contains received at input 36 .

The power amplifier 43 associated with the difference loudspeaker 10 need only have about 10-20% of the power output of the power amplifiers associated with the other loudspeakers 28 , 29 .

The loudspeaker unit is to reproduce a traditional two-channel stereophonic signal utilizing some properties of the sum-and-difference system. In use, the unit is preferably placed on a flat surface 44 which extends around the sides of the unit. The two channels (left and right) of the stereo signal are then supplied to two inputs 36 and 37 respectively. The two front speakers 28 and 29 will then output left and right signals respectively, in the manner of a conventional two-speaker stereo system. The two side speakers output signals including left-right and right-left signals, respectively, wherein a side speaker adjacent to the front speaker outputting the left signal outputs a left-right signal, and vice versa. Providing a side speaker output difference signal increases the depth and width obtainable from a stereo signal compared to using the two front speakers alone. Ideally, the listener should be located toward the front of the unit, but can also be located at the rear of the unit.

The unit combines traditional two-speaker stereo speaker technology with aspects of sum-and-difference technology, resulting in a system that improves on both of the aforementioned technologies. The invention also provides the manner in which a conventional two-speaker stereo unit can be modified to improve the reproduction of a stereo signal by adding a difference speaker. For a conventional unit where the left and right loudspeakers are mounted very close together, the improvement is quite significant. Compared to conventional sum-and-difference loudspeaker units, the loudspeaker unit, like the first embodiment described above, has further advantages over conventional sum-and-difference loudspeaker arrangements.

Figures 8 and 9 show how the arrangement of Figures 5-7 could be incorporated into a television or monitor. The television set comprises a housing 50, mounted on the front of which is a screen 51. Two spatially separated loudspeakers 52 are also mounted on the front of the housing 50 . These two speakers correspond to the speakers 28 and 29 of the embodiment of Figs. 5-7, and are arranged to play the left and right channels of a conventional two-channel stereophonic signal. On either side of the rear of the housing are panels 53 which extend towards the front of the housing at an angle of approximately 45°. Loudspeakers 54 corresponding to the loudspeakers 32 of the arrangement of FIGS. Poor out-of-phase signal. The rear of the TV is flat and generally parallel to the front. In use, the rear of the television is to be placed adjacent to a flat surface, such as a wall 55 of a room. In this way, the part of the speaker 54 towards the rear of the television is towards the wall, taking advantage of the surface effect.

The above embodiments have been described by way of example only, and various changes may be made without departing from the invention.

Claims (32)

1, a kind of reproduction of stereo sound equipment that is used for, this equipment comprises second transducer that is arranged to reproduce first transducer of an audio signal in two audio signals and is arranged to reproduce another signal, this equipment also comprises the transducer that one or two is other, and each in described one or two other transducer is arranged to reproduce the signal of the difference that comprises described two audio signals.

2, equipment according to claim 1, this equipment comprises the shell that defines partially enclosed at least space, one or more being installed on the described shell and with described partially enclosed space in the wherein said transducer is connected.

3, equipment according to claim 2, wherein all described transducers all are installed on the described shell and with described partially enclosed space and are connected.

4, according to the described equipment of aforementioned each claim, wherein said first transducer is arranged to substantially parallel and direction apart is pointed in the output of self with second transducer.

5, equipment according to claim 4, described one or two the other transducer that wherein is arranged to reproduce the signal of the difference that comprises described two audio signals are arranged to the output of self pointed to basically with described first transducer and second transducer and are arranged to roughly rectangular direction of the direction that the output of self is pointed basically.

6, a kind of reproduction of stereo sound equipment that is used for, this equipment comprises the shell that defines partially enclosed at least space, be arranged to generate a audio signal in two audio signals or these two audio signals and first transducer, and two transducers, in these two transducers each all is arranged to reproduce the signal of the difference that comprises described two audio signals, wherein above-mentioned three transducers all are connected with described partially enclosed at least space, and wherein are arranged to reproduce in the transducer of signal of the difference that comprises described two audio signals each and are arranged to the output of self pointed to basically with described first transducer and are arranged to roughly rectangular direction of the direction that the output of self is pointed basically.

7, equipment according to claim 6, wherein said first transducer are arranged to reproduce an audio signal in two audio signals, and second transducer is provided and is used for reproducing another signal.

8, equipment according to claim 7, wherein said first transducer is arranged to substantially parallel and direction apart is pointed in the output of self with second transducer.

9, a kind of reproduction of stereo sound equipment that is used for, this equipment comprises on the surface that is arranged to place general planar or the shell on the surface of contiguous general planar, be arranged to reproduce a audio signal in two audio signals or these two audio signals and first transducer, and two transducers, in these two transducers each all is arranged to reproduce the signal of the difference that comprises described two audio signals, each of described transducer that wherein is arranged to reproduce the signal of the difference that comprises described two audio signals is arranged to the output of self pointed to basically with described first transducer and is arranged to roughly rectangular direction of the direction that the output of self is pointed basically, and the described transducer that wherein is arranged to reproduce the signal of the difference that comprises described two audio signals is arranged with respect to described shell, be placed on the surface of general planar with the described shell of box lunch or during contiguous general planar surperficial, two transducers all are oriented the direction of extending towards the plane on described surface is pointed in the output of himself basically.

10, equipment according to claim 9, wherein said first transducer is arranged to reproduce an audio signal in described two audio signals, and second transducer be provided to reproduce another signal, and described first transducer and second transducer are arranged to substantially parallel and direction apart is pointed in the output of self.

11, according to the described equipment of aforementioned each claim, wherein each transducer is a loud speaker.

12, according to the described equipment of aforementioned each claim, one or two transducer that wherein is arranged to reproduce the signal of the difference that comprises two audio signals is arranged to reproduce basically the signal of out-phase each other, and two out-of-phase signals are pointed to different directions.

13, according to the described equipment of each claim in the claim 2,3,6,7,8,9 and 10, wherein said shell has two openings, sends the signal of the difference that comprises described two audio signals by described two openings.

14, equipment according to claim 13, wherein said shell is arranged to place on the surface of general planar or the surface of contiguous general planar, and described opening is positioned on the described shell, so that be placed on the smooth surface or contiguous smooth when surperficial the contiguous described surface of described opening when described shell.

15, according to claim 13 or 14 described equipment, wherein said shell comprises at least one fully smooth surface.

16, equipment according to claim 15, wherein said fully smooth surface forms the bottom surface and/or the side of described shell.

17, according to the described equipment of each claim in the claim 13～16, wherein said shell comprises from the one or more smooth surface of contiguous described opening or contiguous each opening extension.

18, according to the described equipment of each claim in the claim 2,3,6,7,8,9,10 and 13～17, wherein said shell comprises opening, by described opening send comprise described two audio signals and signal.

19, according to the described equipment of each claim in the claim 2,3,6,7,8,9,10 and 13～17, wherein said shell comprises one or two opening, sends described two audio signals respectively by described opening.

20, according to claim 18 or 19 described equipment, wherein said shell comprises other opening, and this opening forms valve, and this valve is as the pressure-reducing valve in described partially enclosed at least space.

21, equipment according to claim 20, wherein said valve lead to the conduit or the pipe that extend to the small part encapsulation that is being formed by described shell.

22, according to claim 20 or 21 described equipment, wherein except providing described valve, described shell is a complete closed.

23, equipment according to claim 9 or when right require in 10～22 a certain direct or indirect quote claim 9 time according to the described equipment of this claim, it is the direction that the angle between 1～8 degree is extended that two transducers that wherein are arranged to reproduce the signal of the difference that comprises described two audio signals are oriented the plane that the output of self is pointed to described relatively surface.

24, it is that angle between 1～8 degree is extended the direction of extending towards the plane on one or more smooth surfaces from contiguous described opening or contiguous each opening part that equipment according to claim 17, the transducer that wherein is arranged to reproduce the signal of the difference that comprises described two audio signals are oriented that direction with the output of himself is decided to be basically with described relatively surface.

25, according to claim 23 or 24 described equipment, the direction of wherein said transducer is decided to be the angle between plane 2～6 degree on described relatively surface.

26, according to claim 23 or 24 described equipment, the direction of wherein said transducer is decided to be the angle between plane 3～5 degree on described relatively surface.

27, use the described equipment of aforementioned each claim to reproduce the method for two channel stereo signal, the described transducer that wherein is used to reproduce the signal of the difference that comprises described two audio signals is driven by the signal of the difference that comprises described two stereo channels, and another transducer by comprise a stereo channels in described two stereo channels or these two stereo channels and signal drive.

28, use the described equipment of each claim in the claim 1～26 to reproduce the method for two channel stereo signal, the described transducer that wherein is used to reproduce the signal of the difference that comprises described two audio signals is driven by the signal of the difference that comprises described two stereo channels, and another drives respectively two sound channels of transducer by described audio signal.

29, according to the described equipment of aforementioned each claim, this equipment comprises the high pass filter of the low frequency amplitude in the difference that is arranged to reduce described two audio signals.

30, according to the described equipment of aforementioned each claim, this equipment comprises can be operated the base lift compensation circuits that is used for strengthening low frequency.

31, according to the described equipment of each claim in the claim 2,3,6,7,8,9,10 and 13～17, wherein said shell is arranged to hold and is used to provide stereophonic signal to drive the device of described transducer.

32, according to the described equipment of aforementioned each claim, this equipment comprises and is used for producing two channel stereo signal to drive the device of described transducer.

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