Patent Application
20050136848
The present invention relates to audio systems for personal use, such as in portable electronic devices and, more particularly, to audio processors for use in portable electronic devices.
Manufacturers and designers of portable electronic devices, such as mobile telephones, frequently seek to reduce the overall dimensions of such devices while maintaining attractive style characteristics for the devices. One consequence of the reduced size for such devices is that less space may be available for the required components that provide the necessary functionality of the phone as well as components that provide additional functionality. As the space available for the hardware components decreases in the portable electronic devices, it may become more difficult to support additional functionality.
Conventional mobile telephones typically provide noise cancellation to suppress unwanted background noise and enable the participants in a conversation to comprehend one another. Noise cancellation may be provided by, for example, applying sophisticated noise cancellation algorithms to signals provided by a microphone disposed in the housing of the mobile telephone.
Noise cancellation algorithms may be used in portable electronic devices having a single microphone or multiple microphones. Single microphone devices may include omnidirectional microphones that are designed to detect sound equally in all directions. Noise cancellation algorithms in phones using omnidirectional microphones may have difficulty differentiating between wanted and unwanted noise.
Time delay processing may be used in portable electronic devices having both single and multiple microphones to enhance the cancellation effect of background noise. Furthermore, microphones may be made somewhat directional (bi-directional or uni-directional), i.e., more sensitive to sound coming from a particular direction, by having respective ports to receive sound from respective sides of the microphone. Multiported, directional microphones may provide improvements over single ported omnidirectional microphones, however, may suffer from other problems caused by, for example, wind noise.
Some conventional electronic devices include multiple microphones. These microphones may be directional microphones designed to be more sensitive in certain directions. With multiple microphones, a noise cancellation algorithm can use the known spatial relationship of the microphones to be more selective of which sounds are cancelled and which sounds are amplified. Thus, the use of two or more microphones provides multiple inputs to the noise cancellation algorithm and may increase the directionality of the cancellation algorithm. However, adding additional microphones to the mobile telephone may be problematic due to size limitations of portable electronic devices. Accordingly, improved devices for and methods of noise cancellation may be desired.
Embodiments of the present invention provide portable electronic devices including a housing and first and second spaced apart transducers positioned in the housing. A multi-mode audio processor circuit is configured to transmit sound from the first transducer in a first mode of operation and to generate a composite audio signal from sound energy received by the first and second transducers in a second mode of operation.
In some embodiments of the present invention, the multi-mode audio processor circuit may be configured to generate an audio signal from sound energy received by the second transducer in the first mode of operation. The multi-mode audio processor circuit may be further configured to combine first and second audio signals produced from sound energy received by the first and second transducers, respectively, in the second mode of operation to generate a noise-attenuated audio signal.
In further embodiments of the present invention, an audio amplifier may be configured to be coupled to the first transducer in the first mode of operation and a preamplifier may be configured to be coupled to the first transducer in the second mode of operation.
In still further embodiments of the present invention, a switch may be coupled to the first transducer and configured to isolate a path of the audio amplifier from a path of the preamplifier during the first and second modes of operation. The switch may be configured to be in a first position coupled between the first transducer and the audio amplifier in the first mode of operation and to be in a second position coupled between the first transducer and the preamplifier in the second mode of operation.
Some embodiments of the present invention provide a mobile terminal including a housing, a microphone positioned in the housing and a speaker positioned in the housing remote from the microphone. A multi-mode audio processor circuit may be configured to apply noise cancellation to first and second microphone inputs thereof, the first microphone input being coupled to the microphone and the second microphone input being coupled to the speaker.
Further embodiments of the present invention provide a mobile terminal including a multi-mode audio processor circuit operatively associated with a transducer, the multi-mode audio processor circuit being configured to operate the transducer as a speaker during a first mode of operation and a microphone during a second mode of operation.
Some embodiments of the present invention provide a method of operating a mobile terminal including transmitting sound from a first transducer in a first mode of operation and generating a composite audio signal from sound energy received by the first transducer and a second transducer in a second mode of operation.
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. In the drawings, the relative sizes of regions or features may be exaggerated for clarity. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It will be understood that although the terms first and second are 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 element. Thus, a first element discussed below may be termed a second element, and similarly, a second element may be termed a first element without departing from the scope of the present invention. As used herein the term “and/or” includes any and all combinations of one or more of the associated listed items.
The present invention will be described below with respect to embodiments of the invention illustrated in
Multi-mode audio processor circuits according to embodiments of the present invention may be included in portable electronic devices. It will be understood, that, as used herein, the term “portable electronic device” may include a mobile terminal or a cellular radiotelephone with or without a multi-line display; a Personal Communications System (PCS) terminal that may combine a cellular radiotelephone with data processing, facsimile and data communications capabilities; a Personal Data Assistant (PDA) that can include a radiotelephone, pager, Internet/intranet access, Web browser, organizer, calendar and/or a global positioning system (GPS) receiver; and a conventional laptop and/or palmtop portable computer, that may include a radiotelephone transceiver.
Embodiments of the present invention will now be described with reference to the schematic block diagram illustration of a mobile terminal in
The processor 151 may support various functions of the mobile terminal 100. For example, as illustrated in
The speech/data processing circuit 155 as well as other functional modules not illustrated in
The transceiver 130, the speech/data processing circuit 155 and other components of the mobile terminal 100 may be implemented using a variety of hardware and software. For example, operations of the transceiver 130 and/or the speech/data processing circuit 155 may be implemented using special-purpose hardware, such as an application specific integrated circuit (ASIC) and programmable logic devices such as gate arrays, and/or software or firmware running on a computing device such as a microprocessor, microcontroller or digital signal processor (DSP). Although functions of the transceiver 130 and the other circuits shown in
The base station transceiver 24 is typically a radio transceiver(s) that defines an individual cell in a cellular network and communicates with the mobile terminal 100 and other mobile terminals in the cell using a radio-link protocol. Although only a single base station transceiver 24 is shown, it will be understood that many base station transceivers may be connected through, for example, a mobile switching center and other devices to define a wireless communications network.
Although the present invention may be embodied in communication devices or systems, such as the mobile terminal 100, it will be understood that the present invention is not limited to such devices and/or systems. Instead, the present invention may be embodied in any apparatus that may utilize a multi-mode audio processor circuit according to embodiments of the present invention.
In accordance with various embodiments of the present invention, a multi-mode audio processor circuit 157 disposed within the mobile terminal 100 is configured to switch the mobile terminal 100 between a first mode of operation and a second mode of operation. It will be understood that the multi-mode audio processor circuit 157 may include, for example, amplifiers and other electronics to provide operations according to embodiments of the present invention. The multi-mode audio processor circuit 157 may be configured to transmit sound from the speaker/microphone 180 (first transducer), i.e., transmit a signal to a user via the speaker/microphone 180, and to generate an audio signal from sound energy received by the microphone 190 (second transducer) in the first mode of operation. In other words, the speaker/microphone 180 may operate as, for example, a loudspeaker in the first mode of operation and the microphone 190 may operate as, for example, an electret microphone in the first mode of operation. The mobile terminal 100 may operate in the first mode of operation, when the mobile terminal 100 is idle, i.e., waiting for a call, or is receiving a request for a call from the base station 24. The speaker/microphone 180 may be used to provide an alerting tone to notify the user of the call request in the first mode of operation. As discussed above, musical instrument digital interface (MIDI) signals may be supplied to the speaker/microphone 180 by a MIDI synthesizer 170 to provide, for example, polyphonic alerting tones.
Once the call is established and the alerting tones may no longer be active, the multi-mode audio processor circuit 157 may be configured to switch the mobile terminal from the first mode of operation to the second mode of operation. The multi-mode audio processor circuit 157 may be configured to receive sound energy at the speaker/microphone 180 and microphone 190 in the second mode of operation. In other words, the first transducer 180 may operate as a dynamic microphone in the second mode of operation and the second transducer 190 transducer may still operate as an electret microphone in the second mode of operation. The speaker/microphone 180 and microphone 190 receive sound energy and first and second audio signals are produced from the sound energy received by the speaker/microphone 180 and microphone 190. The multi-mode audio processor circuit 157 may be further configured to combine the first and second audio signals to generate a noise-attenuated audio signal. Thus, a composite audio signal may be generated from sound energy received by the speaker/microphone 180 and microphone 190 in the second mode of operation.
In some embodiments of the present invention, the speaker/microphone 180 may operate as both a dynamic speaker and a dynamic microphone during hands-free operation of the handset, for example, using a push-to-talk functionality, when the user is on a call. These embodiments of the present invention may include a voice activity detector 191 coupled to the microphone 190 in the housing of the portable electronic device as illustrated in
Accordingly, portable electronic devices including multi-mode audio processor circuits 157 according to embodiments of the present invention may apply two-microphone noise cancellation algorithms without providing two physical microphones in the housing of the portable electronic device. In certain embodiments, the speaker/microphone 180 and microphone 190 may have as large a distance as possible between them. The spatial relationship of the speaker/microphone 180 and microphone 190 may be used in the noise cancellation algorithm to be more selective of which sounds are cancelled and which sounds are amplified. For example, the microphone 190 may be positioned closer to where a user's voice originates, for example, close to the user's mouth. Thus, the user's voice (sound energy) will reach the microphone 190 and the speaker/microphone 180 at different times and with different amplitudes. Accordingly, there will be a time delay between when the speaker/microphone 180 and microphone 190 receive the voice signals (sound energy). In contrast, background noise will likely reach the speaker/microphone 180 and microphone 190 at approximately the same time. Thus, the multi-mode audio processor circuit 157 may use the time delays as well as amplitude differences, as well as other characteristics, to determine which signals to amplify and which signals to suppress to provide a composite noise-attenuated audio signal.
It will be understood that two-microphone (multi-microphone) noise cancellation algorithms that use, for example, special relationships, time delay, amplitude differences, spectral characteristics, the characterization of the human voice and the like, to determine which signals to amplify and which signals to suppress are known to those having skill in the art. Accordingly, the details with respect to noise cancellation algorithms will not be discussed further herein. Furthermore, the microphone 190 may be any type of microphone known to those of skill in the art capable of being used in a portable electronic device. For example, the microphone 190 may be, for example, omnidirectional, multidirectional, multiported, condenser, electret, ribbon, dynamic, piezo-type and the like without departing from the scope of the present invention.
A transducer assembly 187 according to embodiments of the present invention will now be described with reference to the schematic block diagram illustration of
As further illustrated in
As further illustrated in
A switch 181 is also provided to isolate a path of the audio amplifier 183 from a path of the first preamplifier 185. As illustrated in
Referring now to
A composite audio signal may be generated from sound energy received by the first transducer and a second transducer (block 320) in the second mode of operation. The first and second transducers are configured to operate as microphones during the second mode of operation. The mobile terminal may operate in the second mode of operation when a call request to the mobile terminal is accepted by a user of the mobile terminal. In some embodiments of the present invention, a multi-mode audio processor circuit may be configured to receive sound energy/audio signals from the first and second transducers at first and second microphone inputs, respectively, and generate the composite audio signal from sound energy received by the first and second transducers in a second mode of operation. Accordingly, a two-microphone noise cancellation algorithm may be provided in mobile terminals having only one physical microphone, thereby possibly providing room in the housing of the mobile terminal for optional functionality.
Referring now to
Sound energy may be received at the first and second transducers in the second mode of operation (block 450). It will be understood that the first and second transducers may receive the sound energy created by, for example, a human voice, at different times and with different amplitudes, as one of the transducers may be positioned closer to the source of the sound energy, for example, a user's mouth. A multi-mode audio processor circuit may receive the sound energy from the first and second transducers at first and second microphone inputs, respectively, and combine first and second audio signals produced from the sound energy received by the first and second transducers, respectively, in the second mode of operation (block 460). A single noise-attenuated audio signal may be generated based on the combined first and second audio signals (block 470).
Referring now to
If voice activity is detected (block 540) above a certain threshold at the microphone, the speaker/microphone may be configured to operate as a microphone (block 550). Sound energy may be received at the microphone and the speaker/microphone in the second mode of operation. It will be understood that the microphone and speaker/microphone (first and second transducers) may receive the sound energy created by, for example, a human voice, at different times and with different amplitudes, as one of the transducers may be positioned closer to the source of the sound energy, for example, a user's mouth. A multi-mode audio processor circuit may receive the sound energy from the first and second transducers at first and second microphone inputs, respectively, and combine first and second audio signals produced from the sound energy received by the first and second transducers, respectively, in the second mode of operation (block 560). A single noise-attenuated audio signal may be generated based on the combined first and second audio signals (block 570). On the other hand, when voice activity is not detected at the microphone (block 540), the speaker/microphone may operate as a speaker in the first mode of operation (block 545) and the path of the microphone may be disabled until voice activity is detected.
As discussed briefly above with respect to
In the drawings and specification, there have been disclosed typical illustrative embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.
