Patent Application
20240236551
The various embodiments described in this document relate in general to the field of hand-held devices, and more specifically to a loudspeaker assembly and a hand-held device including the same.
In the past decade, mobile phones have become very popular. A loudspeaker assembly is configured in the mobile phone to output received audio, such as music or voice from the opposite end of a call. In some scenarios, it is possible that the loudspeaker assembly is used in a mode that the mobile phone is held in front of a user's face (as opposed to being held to the ear). In such a mode, a loudspeaker in the loudspeaker assembly is often used as a hands-free loudspeaker.
However, a hands-free loudspeaker is known to have significant coloration from the reflections from the user's hands. Accordingly, there is a need to provide a loudspeaker assembly in hand-held devices that can reduce significantly the coloration of sound created by hand reflections, and in stereo use reduce the response differences between channels caused by hand reflections.
According to one aspect of the present disclosure, a loudspeaker assembly is provided. The loudspeaker assembly includes at least one loudspeaker driver and at least two output ports. The at least one loudspeaker driver and the at least two ports are configured so that the loudspeaker assembly has a unidirectional polar pattern over a desired frequency range.
In some embodiments, the loudspeaker assembly includes at least one or a combination of a loudspeaker unit of a first type, a loudspeaker unit of a second type and a loudspeaker unit of a third type. The loudspeaker unit of the first type has a sealed enclosure and a driver disposed in the sealed enclosure. The loudspeaker unit of the second type has a partially open enclosure and a driver disposed in the partially open enclosure. The loudspeaker unit of the third type has a driver with an open baffle or a driver with acoustically equal cavities on both sides.
In some embodiments, the loudspeaker assembly includes two loudspeaker units of the first type, two audio signal amplifiers and a delay. Two loudspeaker units of the first type have opposite phase, and are fed with separate signals. One of the separate signals is obtained by processing a source signal with one of the two audio signal amplifiers and the delay, and another of the separate signals is obtained by processing the source signal with another of the two audio signal amplifiers.
In some embodiments, the loudspeaker assembly includes a loudspeaker unit of the second type, an audio signal amplifier and an acoustical filter. The acoustical filter is configured to adjust acoustic outputs from two sides of the loudspeaker unit of the second type. The loudspeaker unit of the second type is fed with a signal obtained by processing a source signal with the audio signal amplifier.
In some embodiments, the loudspeaker assembly includes a loudspeaker unit of the first type, a loudspeaker unit of the third type, two audio signal amplifiers and an equalizer. The loudspeaker unit of the first type is fed with a signal obtained by processing a source signal with one of the two audio signal amplifiers, and the loudspeaker unit of the third type is fed with a signal obtained by processing the source signal with another of the two audio signal amplifiers and the equalizer.
In some embodiments, the loudspeaker assembly includes two loudspeaker units of the first type, two loudspeaker front cavities and two output ports. Each of the two loudspeaker units of the first type has a rear cavity, that is space not occupied by the driver in the sealed enclosure. Two rear cavities are next to each other. The two loudspeaker front cavities are arranged at two sides of the two loudspeaker units of the first type, and the two output ports are connected to the two loudspeaker front cavities respectively.
In some embodiments, the loudspeaker assembly includes a loudspeaker unit of the second type, a loudspeaker front cavity, a front output port and a rear output port. The loudspeaker unit of the second type has a rear cavity, that is space not occupied by the driver in the partially open enclosure. The driver in the partially open enclosure is facing the loudspeaker front cavity. The rear cavity is next to the rear output port. The rear output port is provided with an acoustic resistance element on a side wall that is different from a side wall next to the rear cavity.
In some embodiments, the loudspeaker assembly further includes a loudspeaker housing, configured to accommodate the at least one loudspeaker driver. The at least two output ports includes two output ports, connected to the loudspeaker housing.
In some embodiments, the loudspeaker assembly includes at least one or a combination of a wideband or low-frequency loudspeaker with an omnidirectional polar pattern, and a wideband or high frequency loudspeaker, with a cardioid, dipole or other directional polar pattern, or with an omnidirectional polar pattern.
In some embodiments, the loudspeaker assembly includes a loudspeaker housing, two omnidirectional loudspeaker units disposed in the loudspeaker housing, and two output ports connected to the loudspeaker housing.
In some embodiments, the loudspeaker assembly includes a first loudspeaker housing, an omnidirectional loudspeaker unit disposed in the first loudspeaker housing, a first output port connected to the first loudspeaker housing, a second loudspeaker housing, a cardioid loudspeaker unit disposed in the second loudspeaker housing, and a second output port and a third output port connected to the second loudspeaker housing;
In some embodiments, the loudspeaker assembly includes a first loudspeaker housing, a wideband loudspeaker unit disposed in the first loudspeaker housing, a first output port connected to the first loudspeaker housing, a second loudspeaker housing, a high frequency loudspeaker unit disposed in the second loudspeaker housing, and a second output port connected to the second loudspeaker housing. The first and second output ports are facing towards a same direction;
In some embodiments, the loudspeaker assembly includes a first loudspeaker housing, a wideband loudspeaker unit disposed in the first loudspeaker housing, a first output port connected to the first loudspeaker housing, a second loudspeaker housing, a high frequency loudspeaker unit disposed in the second loudspeaker housing, and a second output port connected to the second loudspeaker housing. The first and second output ports are facing towards different directions.
In some embodiments, the loudspeaker assembly includes a first loudspeaker housing, a first omnidirectional unit disposed in the first loudspeaker housing, a first output port connected to the first loudspeaker housing, a second loudspeaker housing, a dipole loudspeaker unit disposed in the second loudspeaker housing, and a second output port and a third output port connected to the second loudspeaker housing, a third loudspeaker housing, a second omnidirectional unit disposed in the third loudspeaker housing, and a fourth output port connected to the third loudspeaker housing. The first loudspeaker housing and the third loudspeaker housing are arranged at two sides of the second loudspeaker housing. All the output ports are facing towards a same direction and are arranged symmetrically around a common center point;
In some embodiments, the loudspeaker assembly includes a first loudspeaker housing, an omnidirectional unit disposed in the first loudspeaker housing, a first output port and a second output port connected to the first loudspeaker housing, a second loudspeaker housing, a dipole loudspeaker unit disposed in the second loudspeaker housing, a third output port and a fourth output port connected to the second loudspeaker housing. All the output ports are facing towards a same direction and the first and second output ports are arranged symmetrically relative to the omnidirectional loudspeaker unit.
According to another aspect of the present disclosure, a hand-held device is provided. The hand-held device includes a device housing, and a loudspeaker assembly disposed in the device housing. The loudspeaker assembly may be described as above.
The present embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references may indicate similar elements.
This specification discloses one or more embodiments that incorporate the features of this disclosure. The disclosed embodiment(s) merely exemplify the disclosure. The scope of the disclosure is not limited to the disclosed embodiment(s). The disclosure is defined by the claims appended hereto.
The embodiment(s) described, and references in the specification to “one embodiment”, “an embodiment”, “an example embodiment”, etc., indicate that the embodiment(s) described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is understood that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
There are various implementations for reducing coloration from the reflections from the user's hands. The embodiments of the present disclosure are related to loudspeaker arrangements in a hand-held device. In the arrangements, loudspeaker(s) of a first type (which may be a wideband or low-frequency loudspeaker with an Omnidirectional polar pattern) and loudspeaker(s) of a second type (which may be a wideband or high frequency loudspeaker, with a cardioid, dipole or other directional polar pattern, or in some implementations, an omnidirectional loudspeaker) are provided. Moreover, respective numbers and layouts of the loudspeakers of the first and second types are designed, and the relative phase and/or response magnitude between the loudspeakers of the first and second types are adjusted in corresponding transition frequency ranges. In this way, a sound field with a directive polar pattern over the desired frequency range can be obtained, and the coloration of sound created by hand reflections can be reduced significantly.
The basic principles of creating loudspeakers with unidirectional (cardioid) polar pattern are well known, but they have not been widely applied to portable devices.
The principle of creating a cardioid polar pattern in an electroacoustic transducer emerged first in microphone designs in 1933 and was later adopted to loudspeaker design either as passive designs (e.g. acoustic resistance enclosures) or through the use of multiple drivers with active electronics. The use of directional loudspeakers in mobile devices is not common due to dynamic range loss of most implementations. That is, the basic principles of creating loudspeakers with unidirectional (cardioid) polar pattern are well known, but they have not been widely applied to portable devices.
In addition, the use of directional microphones is somewhat common in telecommunications applications, especially in accessories, but there are only a few attempts to use directional loudspeakers. One well-known reason for avoiding directional loudspeakers is that their maximum output especially at low frequencies is limited, and the required acoustical symmetry imposes constraints on the acoustical design and driver placement. The low-frequency problem is also addressed in the present disclosure.
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In addition, the loudspeaker ports 103 are arranged in a way that directional response is obtained in the loudspeaker close to the user's hand or close to a surface (existing technology describes handheld device loudspeakers that function well only when the device is essentially in the free air), and providing frequency-dependent polar pattern where the transition frequency is defined according to the hand-device acoustical interaction. The new features of the embodiments of the present disclosure have not been presented in any known implementation of portable device loudspeaker.
It should be appreciated by those of skill in the art that, gradient loudspeakers typically require a large amount of low-frequency boost to achieve flat on-axis response, since their operation relies on cancelling part of the radiated sound by having either the loudspeakers wired out of phase with suitable delays and equalization, or by utilizing the out-of-phase back radiation of an individual loudspeaker driver. This can be acceptable in large loudspeaker assemblies, such as sound reinforcement systems where the principle is becoming increasingly more popular, but in telecommunications loudspeakers the low-frequency output capability is limited, and so the loudspeaker should preferably be operated in an omnidirectional mode at low frequencies.
Simulations and measurements indicate that the user's hand provides no significant boost to a loudspeaker's below 500 Hz, and the boost increases, but remains relatively angle-independent up to about 1500-2000 Hz. This implies that an omnidirectional loudspeaker is usable up to about 1000-1500 Hz, and above that directional operation is preferable, while a directional loudspeaker loses some efficiency at low frequencies when held in hand, so omnidirectional operation is preferable at lower frequencies. Some methods for achieving the desired operation can be divided into two main categories:
Using a frequency dependent phase inversion, achieved e.g. through application of inverting all-pass filters between two separate transducers, and optionally frequency dependent delay difference so that at low frequencies both transducers radiate essentially in phase. This approach maximizes the available low-frequency output for a given number of transducers.
Attenuating the low-frequency output of one transducer, so that cancellation occurs only in a portion of the frequency range. This approach allows the high-frequency transducer to be designed for smaller size. Also in this case frequency dependent delay and phase inversion can be applied, and they are beneficial, but not essential. This approach is not known from existing technology for any type of loudspeaker.
If the unidirectional radiation is achieved through a combination of a dipole and omnidirectional acoustical source, then it is preferable to use two output ports for the omnidirectional source, placed symmetrically around the center of the dipole radiator ports so that the unidirectional radiation characteristics are achieved over a very wide frequency range.
If the polar pattern is implemented as frequency dependent, then a preferred transition frequency range from omnidirectional operation to unidirectional operation is with typical smart phone or handheld game set is from approximately 800 Hz to approximately 2000 Hz.
In conclusion, the embodiments of the present disclosure can reduce significantly the coloration of sound created by hand reflections, and in stereo use reduces the response differences between channels caused by hand reflections.
In some embodiments, a loudspeaker assembly is provided. The loudspeaker assembly includes at least one loudspeaker driver and at least two output ports. The at least one loudspeaker driver and the at least two ports are configured so that at least the loudspeaker assembly close to the hand of the user has unidirectional (typically cardioid) polar pattern over a desired frequency range (e.g. across either the entire frequency range or only at high frequencies). The implementation alternatives and the expected performance are discussed in more detail in the following illustration.
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In this embodiment, the desired polar pattern is achieved by a combination of the acoustic outputs of two units with essentially identical polar patterns, and with signal processing applied to the input signals of the units.
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In this embodiment, the desired polar pattern is achieved by adjusting the acoustic outputs from two sides of a loudspeaker unit with purely acoustical means
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In this embodiment, the desired polar pattern is achieved by a combination of two units acoustically different polar patterns and with signal processing applied to the input signals of the units.
In conclusion, the desired polar pattern is achieved through 1) as an acoustic sum of two (or more) individual loudspeaker drivers, with suitably delayed/equalized signals, or 2) through purely acoustical means (ports, cavities, and resistance elements) using single driver to achieve the desired polar pattern.
In some embodiments, to achieve the desired frequency variable polar pattern, all the loudspeakers won't in some cases reproduce the entire frequency range.
It should be appreciated that a direction shown as “Towards listener” in
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It will be understood that, although the terms first, second, etc., are, in some instances, used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first omnidirectional loudspeaker output port could be termed a second omnidirectional loudspeaker output port, and, similarly, a second omnidirectional loudspeaker output port could be termed a first omnidirectional loudspeaker output port, without departing from the scope of the various described embodiments.
The terminology used in the description of the various described embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various described embodiments and the appended claims, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms “includes,” “including,” “comprises,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the scope of the claims to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments were chosen in order to best explain the principles underlying the claims and their practical applications, to thereby enable others skilled in the art to best use the embodiments with various modifications as are suited to the particular uses contemplated.
