Balanced push-pull loudspeaker device, a control method thereof, and an audio processing circuit

A balanced push-pull loudspeaker device includes a loudspeaker box, a first loudspeaker component, a second loudspeaker component and an audio processing unit. The audio processing unit generates a bass audio signal according to low frequency parts of a first audio channel signal and of a second audio channel signal, mixes the bass audio signal and a high frequency part of the first audio channel signal, outputs a mixture of the bass audio signal and the high frequency part of the first audio channel signal to the first loudspeaker component, inverts the bass audio signal, mixes the inverted bass audio signal and a high frequency part of the second audio channel signal, and outputs a mixture of the inverted bass audio signal and the high frequency part of the second audio channel signal to the second loudspeaker component. This disclosure also provides a control method applied to the above loudspeaker device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 105107189 filed in Taiwan, R.O.C. on Mar. 9, 2016, the entire contents of which are hereby incorporated by reference.

BACKGROUND

Technical Field

This disclosure relates to a balanced push-pull loudspeaker device and a control method thereof, an audio processing circuit and a processing method of audio signals, and more particularly to a loudspeaker device having at least two loudspeaker components, and a control method thereof.

Related Art

Because low frequency sound waves have longer wavelengths, the air volume to be pushed for generating such sound waves is greater than that for high frequency sound waves. When a loudspeaker component reproduces low frequency sounds, the vibration diaphragm of the loudspeaker component must have a larger area to push more air to generate resonance in order to present low frequency sound effects more smoothly. In a conventional loudspeaker device for reproducing low frequency sounds, a loudspeaker component is usually disposed on a loudspeaker box of a corresponding capacity along with the performance parameters of the loudspeaker component. As a result, the loudspeaker component can generate the sound effects at exact harmonic frequencies and the low frequency sound effects are enhanced.

However, in consideration of easy disposition and aesthetic purpose, the loudspeaker component and the capacity of the loudspeaker box in a currently available loudspeaker device have been designed to have smaller and smaller sizes, making the frequency response of the loudspeaker device fail to better work in low frequency region. As the loudspeaker reproduces the low frequency sounds, a sound distortion easily occurs.

SUMMARY

This disclosure provides a balanced push-pull loudspeaker device and a control method thereof, an audio processing circuit, and a processing method of audio signals to solve the problem that a conventional loudspeaker device has a poor frequency response in low frequency region.

According to one or more embodiments of this disclosure, a balanced push-pull loudspeaker device includes a loudspeaker box, a first loudspeaker component, a second loudspeaker component and an audio processing module. The loudspeaker box has a first opening and a second opening on the casing of the loudspeaker box. The first loudspeaker component includes a first vibration diaphragm which covers the first opening of the loudspeaker box and sinks into the inner space of the loudspeaker box relative to the first opening. The second loudspeaker component includes a second vibration diaphragm which covers the second opening of the loudspeaker box and sinks into the inner space of the loudspeaker box relative to the second opening. The audio processing module is configured to generate a bass audio signal according to a low frequency part of a first audio channel signal and a low frequency part of a second audio channel signal, mix the bass audio signal and a high frequency part of the first audio channel signal, and output a mixture of the bass audio signal and the high frequency part of the first audio channel signal to the first loudspeaker component. The audio processing module is also configured to invert the bass audio signal, mix the inverted bass audio signal and a high frequency part of the second audio channel signal, and output a mixture of the inverted bass audio signal and the high frequency part of the second audio channel signal to the second loudspeaker component. Besides, when the first loudspeaker component and the second loudspeaker component output sound effects, the first vibration diaphragm and the second vibration diaphragm respectively thrust in two opposite directions relative to the inner space of the loudspeaker box.

One or more embodiments of this disclosure provide a control method of a balanced push-pull loudspeaker device including a loudspeaker box, a first loudspeaker component and a second loudspeaker component. The first loudspeaker component includes a first vibration diaphragm, and the second loudspeaker component includes a second vibration diaphragm. The control method includes the following steps: generating a bass audio signal according to a low frequency part of a first audio channel signal and a low frequency part of a second audio channel signal, mixing the bass audio signal and a high frequency part of the first audio channel signal and providing a mixture of the bass audio signal and the high frequency part of the first audio channel signal to the first loudspeaker component, inverting the bass audio signal to generate an inverse bass audio signal, mixing the inverted bass audio signal and a high frequency part of the second audio channel signal and providing a mixture of the inverted bass audio signal and the high frequency part of the second audio channel signal to the second loudspeaker component, and the first vibration diaphragm and the second vibration diaphragm thrusting in two opposite directions relative to the inner space of the loudspeaker box when the first loudspeaker component and the second loudspeaker component output sound effects.

According to one or more embodiments of this disclosure, an audio processing circuit is capable of converting a number of original audio channel signals into a number of terminal audio channel signals and includes a low pass filtering unit, a high pass filtering unit, an inverting unit and a mixing unit. The low pass filtering unit is configured to filter a low frequency part out of the original audio signals. The high pass filtering unit is configured to filter a number of high frequency parts out of the original audio signals. The inverting unit is configured to invert the low frequency part to output an inverse low frequency part. The mixing unit is configured to mix the low frequency part with one of the high frequency parts, output a mixture of the low frequency part and the high frequency part as one of the terminal audio channel signals, mix the inverse low frequency part with another one of the high frequency parts, and output a mixture of the inverse low frequency part and the high frequency part as another one of the terminal audio channel signals.

According to one or more embodiments of this disclosure, a processing method of audio signals is applied to convert signals of original audio channels into signals of terminal audio channels. The processing method includes the following steps: filtering a low frequency part out of the signals of the original audio channels, filtering a plurality of high frequency parts out of the signals of the original audio channels, inverting the low frequency part to output an inverse low frequency part, mixing the low frequency part with one of the high frequency parts, outputting a mixture of the low frequency part and the high frequency part as one of the signals of the terminal audio channels, mixing the inverse low frequency part with another one of the high frequency parts, and outputting a mixture of the inverse low frequency part and the high frequency part as another one of the signals of the terminal audio channels.

In view of the above, one or more embodiments of this disclosure provide a balanced push-pull loudspeaker device and a control method thereof, an audio processing circuit and a processing method of audio signals. The low frequency part of the first audio channel signal and the low frequency part of the second audio channel signal are mixed to generate a bass audio signal, the high frequency part of the first audio channel signal is mixed with the bass audio signal to generate a mixed signal, the high frequency part of the second audio channel signal is mixed with the inverted bass audio signal to generate another mixed signal, and then the mixed signals are respectively provided to the first loudspeaker component and the second loudspeaker component. In this way, when the first loudspeaker component and the second loudspeaker component output the sound effects, the vibration diaphragms of the first loudspeaker component and the second loudspeaker component respectively thrust in opposite directions relative to the inner space of the loudspeaker box so that the capacity of the inner space of the loudspeaker box is balanced. Therefore, the possibility that the noises and the harmonic distortion are caused as the first vibration diaphragm and the second vibration diaphragm simultaneously thrust in the same direction is reduced.

DETAILED DESCRIPTION

Please referFIG. 1toFIG. 3.FIG. 1is a stereogram of a loudspeaker device according to an embodiment of this disclosure.FIG. 2is a top view of a loudspeaker device according to an embodiment of this disclosure.FIG. 3is a schematic diagram of the thrust done by a first vibration diaphragm of a first loudspeaker component according to an embodiment of this disclosure. As shown in the figures, a loudspeaker device10, such as a complete speaker system, includes a loudspeaker box11, a first loudspeaker component (“FLC”)13, a second loudspeaker component (“SLC”)15and an audio processing module (“APM”)17(shown inFIG. 4). The loudspeaker device10receives an audio signal from, for example, an amplifier or other suitable audio source device, so as to drive the FLC13and the SLC15to output sounds.

The loudspeaker box11has a first opening111and a second opening112on its casing. For example, the loudspeaker box11is made of plastic, planks, medium density fiberboards or other suitable material. This disclosure does not intend to limit the shape, thickness of the casing and internal capacity of the loudspeaker box11. Besides, a sound absorbing material or other element capable of attenuating air vibration inside casing can be disposed in the loudspeaker box11. In this embodiment, the casing of the loudspeaker box11may form the shell of the loudspeaker device10. In another embodiment, the loudspeaker box11may be a box inside the casing of the loudspeaker device10, and a shock absorbing material may be disposed between the loudspeaker box11and the casing.

The FLC13includes a first vibration diaphragm131, an actuator132and a vibration diaphragm frame133. In another embodiment, the FLC13may also include a center cap, a surrounding or other suitable element, which is not limited in this disclosure. The first vibration diaphragm131of the FLC13covers the first opening111of the loudspeaker box11and sinks into the inner space of the loudspeaker box11relative to the first opening111. In other words, the FLC13outputs sounds to the outside of the loudspeaker box11.

Similarly, the SLC15includes a second vibration diaphragm151, an actuator152and a vibration diaphragm frame153. The second vibration diaphragm15covers the second opening112of the loudspeaker box11and sinks into the inner space of the loudspeaker box11relative to the second opening112. The FLC13and the SLC15are active loudspeakers. The FLC13and the SLC15generate magnetic field change in response to received currents or voltages to drive the first vibration diaphragm131and the second vibration diaphragm151which then inwardly or outwardly thrust relative to the inner space of the loudspeaker box11so that the air vibrates to output sounds. The size of the FLC13is not limited to be the same as that of the SLC15. When the first vibration diaphragm131and the second vibration diaphragm151respectively cover the first opening111and the second opening112of the loudspeaker box11, an enclosed space may be formed among the loudspeaker box11, the first vibration diaphragm131and the second vibration diaphragm151.

In this embodiment, the thrust of the first vibration diaphragm131relative to the inner space of the loudspeaker box11refers to that most of the area of the first vibration diaphragm131pushes inwardly into the loudspeaker box11. In practice, the first vibration diaphragm131is distorted when it vibrates, so when the first vibration diaphragm131pushes inwardly into the loudspeaker box11, a small part of the first vibration diaphragm131thrusts outwardly, and vice versa, as shown inFIG. 3. Identically, the vibration of the second vibration diaphragm151is a similar one, so we shall not repeat the detail description here.

The APM17generates a bass audio signal according to the low frequency part of a first audio channel signal (“FACS”) and the low frequency part of a second audio channel signal (“SACS”), mixes the bass audio signal and the high frequency part of the FACS, and outputs a mixture of the bass audio signal and the high frequency part of the FACS to the FLC13. The FLC13outputs sound effects according to the mixture of the bass audio signal and the high frequency part of the FACS. The APM17inverts the bass audio signal, mixes the inverted bass audio signal and the high frequency part of the SACS, and outputs a mixture of the inverted bass audio signal and the high frequency part of the SACS to the SLC15. The SLC15outputs sound effects according to the mixture of the inverted bass audio signal and the high frequency part of the FACS. When the FLC13and the SLC15output sound effects, the first vibration diaphragm131and the second vibration diaphragm151respectively thrust in two opposite directions relative to the inner space of the loudspeaker box. In other words, when the first vibration diaphragm131inwardly thrusts relative to the inner space of the loudspeaker box11, the second vibration diaphragm151outwardly thrusts relative to the inner space of the loudspeaker box11; and vise versa.

To conveniently depict that the present embodiment uses the inverted bass audio signal to make the first vibration diaphragm131and the second vibration diaphragm151respectively thrust in two opposite directions, the following description temporarily omits the high frequency part of the FACS and the high frequency part of the SACS. After the APM17mixes the low frequency part of the FACS and the low frequency part of the SACS to generate the bass audio signal, the FLC13will receive the bass audio signal, and the SLC15will receive the inverted bass audio signal which is 180 degree out of phase with the bass audio signal. When the bass audio signal received by the FLC13is in the positive half of a cycle, the first vibration diaphragm131of the FLC13thrusts outwardly relative to the inner space of the loudspeaker box11. At the meantime, the inverted bass audio signal received by the SLC15is in the negative half of the cycle, the second vibration diaphragm151of the SLC15thrusts inwardly relative to the inner space of the loudspeaker box11, and vice versa.

Therefore, the FLC13receives the bass audio signal, and the SLC15receives the inverted bass audio signal, so that the first vibration diaphragm131of the FLC13and the second vibration diaphragm151of the SLC15respectively thrust in opposite directions. The first vibration diaphragm131and the second vibration diaphragm151, thrusting in opposite directions, balance the internal capacity of the loudspeaker box11. As a result, when the FLC13and the SLC15output sound effects, the barometric pressure inside the loudspeaker box11is approximately equal to the barometric pressure outside the loudspeaker box11. As the capacity of the loudspeaker box11is smaller, by having the diaphragms131and151thrusting in opposite directions, noise and harmonic distortion, caused by huge barometric pressure change inside the loudspeaker box11once the diaphragms131and151simultaneously thrust inwardly or outwardly, may be avoided.

Please refer toFIG. 1andFIG. 4.FIG. 4is a functional block diagram of an APM in an embodiment of this disclosure. As shown in the figures, the APM17includes a first audio processor171, a second audio processor172, a bass mixer173, an inverter174, and output mixers175a,175b. In this embodiment, the APM17receives the FACS from a receiving end CH1and the SACS from a receiving end CH2.

For example, the first audio processor171and the second audio processor172are audio filters configured to filter the audio signal into the high frequency part and the low frequency part. More specifically, the first audio processor171includes a low pass filter and a high pass filter, for example. The first audio processor171outputs the FASC's high frequency part whose frequency is higher than a first cutoff frequency as well as the FASC's low frequency part whose frequency is lower than the first cutoff frequency after receiving and filtering the FACS. The first audio processor171, for example, attenuates or blocks the FASC's low frequency part whose frequency is lower than the first cutoff frequency, in order to output the FASC's high frequency part. The first audio processor171attenuates or blocks the FASC's high frequency part whose frequency is higher than a first cutoff frequency, in order to output the FASC's low frequency part. The first cutoff frequency depends on, for example, the size, Thiele-Small parameters or other factor of the FLC13, which is not limited in this disclosure. Also, the first cutoff frequency can be set by the designer directly according to practical requirements.

Similarly, the second audio processor172includes, for example, a low pass filter and a high pass filter. The second audio processor172outputs the SACS's high frequency part whose frequency is higher than a second cutoff frequency as well as the SACS's low frequency part whose frequency is lower than the second cutoff frequency after receiving and filtering the SACS. The second cutoff frequency depends on, for example, the size, Thiele-Small parameters or other factor of the SLC15. The first cutoff frequency can also be set by the designer directly according to practical requirements, and this disclosure does not intend to limit the way the first cutoff frequency is decided. The bass mixer173is coupled to the first audio processor171and the second audio processor172to receive the low frequency part of the FACS and the low frequency part of the SACS. The bass mixer173also mixes the low frequency part of the FACS and the low frequency part of the SACS to generate the bass audio signal.

The output mixer175areceives the high frequency part of the FACS and the bass audio signal output by the bass mixer173, mixes the high frequency part of the FACS and the bass audio signal to generate a first mixed audio signal, and outputs the first mixed audio signal to the FLC13. On the other hand, the bass mixer173outputs the bass audio signal to the inverter174. The inverter174outputs the inverted bass audio signal to the output mixer175bafter shifting the phase of the bass audio signal by 180 degrees. The output mixer175breceives the high frequency part of the SACS and the inverted bass audio signal, mixes the high frequency part of the SACS and the inverted bass audio signal to generate a second mixed audio signal, and outputs the second mixed audio signal to the SLC15. Accordingly, when the FLC13and the SLC15output sound effects according to the received mixed audio signals, the first vibration diaphragm131of the FLC13and the second vibration diaphragm151of the SLC15respectively thrust in opposite directions relative to the inner space of the loudspeaker box11.

Please refer toFIG. 5.FIG. 5is a functional block diagram of an APM in another embodiment of this disclosure. As shown inFIG. 5, the APM27includes an audio mixer271, a low pass filter272, a first high pass filter273, a second high pass filter274, an inverter275, output mixers276a,276b. Similar to the former embodiment, the APM27receives the FACS from the receiving end CH1and receives the SACS from the receiving end CH2.

The differences between this embodiment and the former embodiment is that the audio mixer271receives and mixes the FACS and the SACS and then outputs the mixture of the FACS and the SACS to the low pass filter272. The low pass filter272filters the mixture of the FACS and the SACS through low pass filtering and outputs the bass audio signal. For example, the low pass filter272attenuates or blocks the high frequency part of the mixture of the FACS and the SACS to output the low frequency part of the mixture as the bass audio signal. The first high pass filter273filters the FACS through high pass filtering and outputs the high frequency part of the FACS. The second high pass filter274filters the SACS through high pass filtering and outputs the high frequency part of the SACS.

The cutoff frequencies of the low pass filter272, the first high pass filter273and the second high pass filter274depend on, for example, the sizes, Thiele-Small parameters or other factors of the FLC23and the SLC25. The cutoff frequencies can also be set by the designer according to practical needs, and this disclosure shall not limit the implementation manner.

The output mixer276areceives the high frequency part of the FACS and the bass audio signal output by the low pass filter272, mixes the high frequency part of the FACS and the bass audio signal to generate a first mixed audio signal, and outputs the first mixed audio signal to the FLC23. On the other hand, the low pass filter272outputs the bass audio signal to the inverter275. After reversing the phase of the bass audio signal by 180 degrees, the inverter275outputs the inverted bass audio signal to the output mixer276b. The output mixer276breceives the high frequency part of the SACS and the inverted bass audio signal, mixes the high frequency part of the SACS and the inverted bass audio signal to generate a second mixed audio signal, and outputs the second mixed audio signal to the SLC25. Therefore, when the FLC23and the SLC25output sound effects according to the received mixed audio signals, the first vibration diaphragm of the FLC23and the second vibration diaphragm of the SLC25respectively thrust in opposite directions relative to the inner space of the loudspeaker box21.

Please refer toFIG. 6andFIG. 7.FIG. 6is a stereogram of a loudspeaker device according to yet another embodiment of this disclosure.FIG. 7is a functional block diagram of an APM in yet another embodiment of this disclosure. As shown in the figures, the loudspeaker device30includes a loudspeaker box31, a FLC33, a SLC35, a third loudspeaker component (“TLC”)37and an APM39. The loudspeaker box31has a first opening311, a second opening312and a third opening313on the casing. The FLC33includes at least a first vibration diaphragm331which covers the first opening311of the loudspeaker box31and sinks into the inner space of the loudspeaker box31relative to the first opening311. The SLC35includes at least a second vibration diaphragm351which covers the second opening312of the loudspeaker box31and sinks into the inner space of the loudspeaker box31relative to the second opening312. The TLC37includes at least a third vibration diaphragm371which covers the third opening313of the loudspeaker box31and sinks into the inner space of the loudspeaker box31relative to the third opening313.

In this embodiment, the FLC33, the SLC35and the TLC37, acting as terminal audio channels, are active loudspeakers. That is, according to received currents or voltages, the FLC33, the SLC35and the TLC37can actively drive the first vibration diaphragm331, the second vibration diaphragm351and the third vibration diaphragm371to inwardly or outwardly thrust relative to the inner space of the loudspeaker box31, which in turn makes air oscillate to output sounds. In this embodiment, the number of loudspeaker components is, for example, but not limited to three. Moreover, this disclosure does not intend to limit the sizes of the FLC33, the SLC35and the TLC37. When the first vibration diaphragm331, the second vibration diaphragm351and the third vibration diaphragm371respectively cover the first opening311, the second opening312and the third opening313of the loudspeaker box31, an enclosed space may be formed among the loudspeaker box31and the vibration diaphragms331,351,371.

As shown inFIG. 7, the APM39includes low pass filters391a˜391c, high pass filters392a˜392c, a mixer393, inverters394a˜394c, output mixers395a˜395cand a signal processor396. The APM39receives the FACS, the SACS and the third audio channel signal (“TACS”) from the receiving ends CH1, CH2, CH3(original audio channels), respectively.

The low pass filters391a˜391crespectively receive and apply low pass filtering to the FACS, the SACS and the TACS. Then, the low pass filters391a˜391crespectively output the FACS's low frequency part at a frequency lower than the first cutoff frequency, the SACS's low frequency part at a frequency lower than the second cutoff frequency and the TACS's low frequency part at a frequency lower than the third cutoff frequency. The high pass filters392a˜392crespectively receive and apply low pass filtering to the FACS, the SACS and the TACS. Then, the high pass filters392a˜392crespectively output the FACS's high frequency part at a frequency higher than the first cutoff frequency, the SACS's high frequency part at a frequency higher than the second cutoff frequency, and the TACS's high frequency part at a frequency higher than the third cutoff frequency.

For example, the first cutoff frequency, the second cutoff frequency and the third cutoff frequency respectively depend on the sizes, Thiele-Small parameters or other factors of the FLC33, the SLC35and the TLC37, but this disclosure does not intend to limit them. Also, the first cutoff frequency, the second cutoff frequency and the third cutoff frequency can be set by the designer according to practical requirements.

The mixer393is coupled to the low pass filter391a˜391cto receive the low frequency parts of the FACS, the SACS and the TACS. The mixer393mixes the low frequency parts of the FACS, the SACS and the TACS to generate the bass audio signal. In an embodiment, besides mixing the low frequency parts of the FACS, the SACS and the TACS to generate the bass audio signal, the mixer393can further adjust the bass audio signal. For example, the mixer393can reduce the sound intensity level of the bass audio signal.

The inverters394a˜394care respectively coupled to the output mixers395a˜395c. The output mixer395ais coupled to the FLC33via the signal processor396. The output mixer395bis coupled to the SLC35via signal processor396. The output mixer395cis coupled to the TLC37via signal processor396. The signal processor396is configured to amplify the mixed audio signals output by the output mixers395a˜395cand output the amplified mixing audio signals to the FLC33, the SLC35and the TLC37, respectively. In another embodiment, the signal processor396is omitted, and the output mixers395a˜395care directly coupled to the FLC33, the SLC35and the TLC37, respectively.

The output mixer395ais coupled to the high pass filter392ato receive the high frequency part of the FACS and selectively accept the inverted bass audio signal from the inverter394aaccording to a control information ct1. In other words, the output mixer395adecides to or not to receive the bass audio signal from the inverter394aaccording to the control information ct1. When the output mixer395areceives the bass audio signal from the inverter394a, it means the output mixer395areceives the inverted bass audio signal. The output mixer395amixes the inverted bass audio signal and the FACS's high frequency part, which is output by the high pass filter392a, to generate a first mixed audio signal, and outputs the first mixed audio signal to the FLC33. When the output mixer395adoes not receive the bass audio signal from the inverter394a, it means that the output mixer395adirectly receives the bass audio signal from the mixer393. The output mixer395amixes the non-inverted bass audio signal and the FACS's high frequency part, which is output by the high pass filter392a, to generate a first audio signal and outputs the first audio signal to the FLC33.

Similarly, the output mixer395bis coupled to the high pass filter392bto receive the high frequency part of the SACS, and selectively receives the bass audio signal from the inverter394baccording to the control information ct1. The output mixer395bmixes either the bass audio signal or the inverted bass audio signal with the high frequency part of the SACS, which is output by the high pass filter392b, to generate a second mixed audio signal, and outputs the second mixed audio signal to the SLC35. The output mixer395cis coupled to the high pass filter392cto receive the high frequency part of the TACS, and selectively receive or block the bass audio signal from the inverter394c, according to the control information ct1. The output mixer395cmixes either the bass audio signal or the inverted bass audio signal with the high frequency part of the TACS, which is output by the high pass filter392c, to generate a third mixed audio signal, and outputs the third mixed audio signal to the TLC37.

Therefore, when the FLC33, the SLC35and the TLC37output sound effects according to the received mixed audio signals, at least two of the first vibration diaphragm331of the FLC33, the second vibration diaphragm351of the SLC35and the third vibration diaphragm371of the TLC37thrust in opposite directions relative to the inner space of the loudspeaker box31. For example, when the control information ct1indicates that the FLC33receives the inverted bass audio signal through the inverter394a, the SLC35receives the inverted bass audio signal through the inverter394b, and the TLC37does not receive the inverted bass audio signal through the inverter394b, so long as the bass audio signal is in the positive half of a cycle, the first vibration diaphragm331and the second vibration diaphragm351inwardly thrust relative to the inner space of the loudspeaker box31, and the third vibration diaphragm371outwardly thrusts relative to the inner space of the loudspeaker box31. In contrast, as the bass audio signal is in the negative half of the cycle, the first vibration diaphragm331and the second vibration diaphragm351outwardly thrust relative to the inner space of the loudspeaker box31, and the third vibration diaphragm371inwardly thrusts relative to the inner space of the loudspeaker box31.

In an embodiment, the control information ct1, for example, is provided by another controller controlling the APM39, or is generated by another control unit of the APM39, but is not limited in this disclosure. The control information ct1is related to the internal capacity, the shape of the inner space of the loudspeaker box31, the number, the sizes and Thiele-Small parameters of the loudspeaker components. In practice, the inner space of the loudspeaker box31is not uniform. In other words, because of the shape of the loudspeaker device30, the position of the APM39in the loudspeaker device30, the volume of the sound absorbing material, or other possible factor, the airflow amounts pushed or pulled by thrust of the vibration diaphragms of the FLC33, the SLC35and the TLC37are different. For example, when the APM39is disposed near the FLC33, in the inner space of the loudspeaker box31, the capacity of the region A neighboring to the FLC33is smaller than the capacity of the region B neighboring to the SLC35as well as the capacity of the region C neighboring to the TLC37, as shown inFIG. 6. As a result, the airflow amount pushed by the FLC33is different from both the airflow amounts pushed by the SLC35and TLC37.

In this example, because the capacity of the region A is smaller than both the region B and the region C, the control information ct1indicates that the FLC33and the neighboring TLC37equally receive the inverted or non-inverted bass audio signal. When the FLC33and TLC37output sound effects, the first vibration diaphragm331and the third vibration diaphragm371thrust in the same direction relative to the inner space of the loudspeaker box31. However, when the SLC35outputs sound effects, the second vibration diaphragm351thrusts in the direction opposite to the first vibration diaphragm331and the third vibration diaphragm371. A person having ordinary skill in the art may design the control information ct1in terms of actual requirements to control thrusting directions of the first vibration diaphragm331, the second vibration diaphragm351and the third vibration diaphragm371, and this embodiment is not limited to above implementation.

In other words, the loudspeaker device30controls the thrusting directions of the first vibration diaphragm331, the second vibration diaphragm351and the third vibration diaphragm371by the control information ct1so that the first vibration diaphragm331, the second vibration diaphragm351and the third vibration diaphragm371can approximately balance the capacity of the inner space of the loudspeaker box31. Therefore, when the FLC33, the SLC35and the TLC37output sound effects, the possibility that the noises and the harmonic distortion are caused by a great change of air pressure inside the loudspeaker box11as all vibration diaphragms simultaneously thrust in the same direction is reduced.

In this embodiment, the FACS, the SACS and the TACS may be mixed before being filtered by the low pass filter. A person having ordinary skill in the art can understand the methods of implementation by referring to the embodiment inFIG. 5, so the related details shall not be repeated here.

To explain the control method of the loudspeaker device more clearly, please refer toFIG. 1toFIG. 3andFIG. 8.FIG. 8is a flow chart of a control method in an embodiment of this disclosure. As shown in the figures, in the step S401, the bass audio signal is generated according to the low frequency part of the FACS and the low frequency part of the SACS; in the step S403, the bass audio signal is mixed with the high frequency part of the FACS, and a mixture of the bass audio signal and the high frequency part of the FACS is provided to the FLC; in the step S405, the bass audio signal is inverted; in the step S407, the inverted bass audio signal is mixed with the high frequency part of the SACS, and a mixture of the inverted bass audio signal and the high frequency part of the SACS is provided to the second loudspeaker. In this way, when the FLC13and the SLC15output sound effects, the first vibration diaphragm131and the second vibration diaphragm151thrust in opposite directions relative to the inner space of the loudspeaker box11. While the inner space occupies a smaller capacity, it turns out that noise and harmonic distortion, which would be caused by a change of air pressure inside the loudspeaker box11if the first vibration diaphragm131and the second vibration diaphragm151simultaneously thrust inwardly or outwardly, could be avoided by having the first vibration diaphragm131and the second vibration diaphragm151respectively thrust in opposite directions. Actually, the control method of the loudspeaker device in this disclosure has been described in the aforementioned embodiments, we shall not repeat describing the control method here.

This disclosure also provides an audio processing circuit for converting signals of a number of original audio channels into signals of a number of terminal audio channels. For example, the original audio channels are the receiving ends CH1˜CH3in the aforementioned embodiment, and the terminal audio channels are the loudspeaker components13,15,23,25,33,35,37. The audio processing circuit includes a low pass filtering unit, a high pass filtering unit, an inverting unit and a mixing unit. For example, the low pass filtering unit includes the low pass filters272,391a,391b, or391cin the aforementioned embodiments. The low pass filtering unit extracts a low frequency part from the signals of the original audio channels. The high pass filtering unit includes the high pass filters273,274,392a,392b, or392cin the aforementioned embodiments. The high pass filtering unit extracts a number of high frequency parts from the signals of the original audio channels. The inverting unit includes, for example, the aforementioned inverters275,394a,394b, or394c. The inverting unit inverts the low frequency part to output an inverse low frequency part. The mixing unit includes, for example, the aforementioned mixers175a,175b,276a,276b,395a,395b, or395c. The mixing unit mixes the low frequency part with one of the high frequency parts to produce a mixture of the low frequency part and the high frequency part as one of the signals of the terminal audio channels. The mixing unit also mixes the inverse low frequency part with another one of the high frequency parts to produce a mixture of the inverse low frequency part and the high frequency part as another one of the signals of the terminal audio channels signals. Actually, the audio processing circuit of this disclosure has been described in the aforementioned embodiments, the detail description shall be skipped here.

This disclosure also provides a processing method of audio signals for converting signals of a number of original audio channels into signals of a number of terminal audio channels. The processing method includes the following steps: filtering a low frequency part out of the signals of the original audio channels, filtering a number of high frequency parts out of the signals of the original audio channels, inverting the low frequency part to output an inverse low frequency part, mixing the low frequency part with one of the high frequency parts for outputting a mixture of the low frequency part and the high frequency part as one of the signals of the terminal audio channels, and mixing the inverse low frequency part with another one of the high frequency parts for outputting a mixture of the inverse low frequency part and the high frequency part as another one of the signals of the terminal audio channels signals. Actually, the processing method of audio signals of this disclosure is described in the aforementioned embodiments; the detail description shall be skipped here.

In view of the above description, one or more embodiments of this disclosure provide a balanced push-pull loudspeaker device and a control method thereof, an audio processing circuit, and a processing method of audio signals. In the disclosure, the low frequency parts of a number of audio channel signals are mixed to generate a bass audio signal, the high frequency part of each audio channel signals is mixed with either the bass audio signal or the inverted bass audio signal to generate a mixed signal, and then the mixed signals are respectively provided to the loudspeaker components. In this way, when the loudspeaker components output sound effects, the vibration diaphragms of the loudspeaker components respectively inwardly or outwardly thrust relative to the inner space of the loudspeaker box so that the capacity of the inner space of the loudspeaker box is approximately balanced. Therefore, the possibility that noise and the harmonic distortion, which would be caused by a great change off air pressure inside the loudspeaker box11if all the vibration diaphragms simultaneously thrust in the same direction, is reduced. Moreover, according to one or more embodiments of this disclosure, each of the audio channel signals is filtered into the low frequency part and the high frequency part, so when the bass audio signal is mixed with the high frequency part of the original audio channel signal, the distortion after mixing may also be reduced and the sounds reproduced by the loudspeaker device may have a high quality.