The present invention relates generally to audio amplifier systems and more particularly, to an audio amplifier system that is operable to enter into a thermal management mode once reaching an upper temperature threshold value that cools the amplifier using low frequency management.
An audio amplifier is a device for increasing the power of a signal, which in the case of audio amplifiers, is an audio signal. Audio amplifiers increase the power of a signal by taking power from a power supply and controlling the output of the amplifier to match the input signal shape, but typically have a much larger amplitude. Audio amplifiers are designed to perform optimally with audio frequencies that generally fall within frequency ranges between 20 Hertz and 20,000 Hertz, which generally corresponds to the frequency range that most humans can hear. The audio amplifier is typically the final stage in the audio playback chain and its purpose is to amplify the analog audio signal generated by a preceding stage to a level that can drive loudspeakers.
During operation audio amplifiers generate heat that needs to be dissipated before reaching a level that may cause damage to the components of the amplifier. The increasing output power utilized by today's audio systems poses serious problems for dissipating the heat produced by the audio amplifier. To prevent the audio amplifier from overheating, some amplifiers use “full frequency range” amplitude limiters. These amplitude limiters limit the amplitude of every portion of the audio signal that is input to the amplifier, regardless of the frequency of the signal, so that the audio amplifier will not generate heat above a predetermined upper level. Other audio amplifiers may simply stop or kick out once the amplifier reaches a predetermined temperature valve. Despite known methods of dissipating heat in audio amplifiers, improvements to the current methods and systems for dissipating heat are needed.
One embodiment according to the present invention discloses a unique heat dissipation system for an audio amplifier of an audio system. Other embodiments include unique apparatuses, systems, devices, hardware, methods, and combinations of these for maintaining the temperature value of an audio amplifier within safe operating levels. Further embodiments, forms, objects, features, advantages, aspects, and benefits of the present invention shall become apparent from the following description and drawings.
a represents a portion of a streaming analog audio signal.
b represents the portion of the streaming analog audio signal illustrated in
a represents a bass portion of a streaming analog audio signal.
b represents the bass portion of the streaming analog audio signal illustrated in
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention is illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
A audio system is disclosed that includes a unique amplification system that is operable, either through computer software or analog circuitry, to effectively cool an amplifier. In one embodiment, once the amplifier reaches a predetermined operating temperature value, a computer program product executable by a control unit causes the control unit to selectively eliminate a first select range of bass frequencies from the streaming audio signal and/or reduce an amplitude value of a second select range of bass frequencies contained in the streaming audio signal. As set forth below, in another embodiment, the computer program product may, in whole or part, be replaced by analog and/or digital circuitry.
As used herein, the term bass frequencies should be construed to cover audio frequencies traditionally found or falling in the bass range. Bass frequencies are those frequencies that have tones of low frequency or range. The audio reproduction of bass frequencies contributes, and sometimes disproportionately, to the heat generated by amplifiers during audio reproduction. In one aspect of the present invention, bass frequencies are those frequencies falling in the frequency range of about 0-300 Hz, which may vary in alternative embodiments.
With reference to
The streaming audio signal provided by the audio source 12 is preferentially in the form of a digital audio signal, but in alternative embodiments, may comprise an analog audio signal that may then be converted to a digital audio signal by an analog-to-digital (“A/D”) converter of the control unit 14. The control unit 14 may be connected with a digital signal processor (“DSP”) or pulse width modulation processor 16 that is used to convert digital audio signals supplied by the control unit 14 to at least one analog audio signal that is supplied as an input to an amplifier 18. In alternative embodiments, more than one analog audio signal may be supplied as an input to the amplifier 18 such as, for example, two audio signals for left and right channels. The audio system 10 can use the amplifier 18, and the amplifier 18 may be designed, to amplify any number of channels, such as is the case in multi-channel audio 5.1 and 6.1 channel systems.
The amplifier 18 may comprise a single stage amplifier or a multi-stage amplifier and may be capable of amplifying the analog audio signals provided as inputs by many magnitudes. The amplifier 18 illustrated in
A first thermal sensor 24 may be connected with the first amplifier stage 20. A second thermal sensor 26 may be connected with the second amplifier stage 22. In alternative embodiments, only one thermal sensor may be used or a thermal sensor may be used for each amplification stage. The thermal sensors 24, 26 may be connected with respective heat sinks or heat dissipation members 23 of the amplifier 18 that are used to dissipate heat from the amplifier 18. However, it should be appreciated that the thermal sensors 24, 26 may be connected anywhere in the amplifier 18 where they are capable of detecting an operating temperature value of the amplifier 18.
The thermal sensors 24, 26 generate electric signals that are indicative of the operating temperature value of the amplifier 18. The readings obtained by the thermal sensors 24, 26 are transmitted to the control unit 14. In the embodiment illustrated in
The audio system 10 may also be connected with at least one speaker 30. In multi-channel audio systems, the audio system 10 may be connected with a plurality of speakers. The amplifier 18 is used to drive the speaker 30 to reproduce the audio recording contained in the streaming audio signal. In the embodiment illustrated in
Referring to
While the audio system 10 is operating in the thermal management mode 54, the thermal management module 50 may continue to monitor the operating temperature value of the amplifier 18 using the thermal sensors 24, 26, which is represented at step 58. If the operating temperature value of the amplifier 18 falls below a predetermined low threshold temperature value, at step 59, the thermal management module 50 ends the thermal management mode 54 of operation. The predetermined low threshold temperature value will vary from audio system to audio system depending upon several design parameters (e.g.—amplifier wattage, heat sink size, and so forth).
In one embodiment, the predetermined threshold temperature value is set somewhat below a safe operating temperature value to ensure that the amplifier 18 is adequately cooled before returning to a normal operating mode. If the operating temperature value of the amplifier 18 does not fall below the predetermined low threshold temperature value, the audio system 10 stays in the thermal management mode 54 until the temperature of the amplifier 18 reaches the predetermined low threshold temperature value. The predetermined low threshold temperature value may also vary from amplifier stage to amplifier stage, depending on the design of the amplifier 18. For example, if amplifier stages share a heat sink, one amplifier stage may not be able to operate under the same thermal conditions as the other and as such, the safe operating temperature range of that amplifier stage will take priority over the other.
Referring to
Once the calibrated range of bass frequencies has been obtained, the high pass filter module 60 begins filtering audio signals contained in the streaming audio signal falling within the calibrated range of bass frequencies, which is represented at step 64. The high pass filter module 60 may buffer the streaming audio signal in order to analyze and filter each audio signal contained in the streaming audio signal that falls within the calibrated range of bass frequencies. In one embodiment, the high pass filter module 60 completely removes or eliminates audio signals in the streaming audio signal that contain frequencies falling within the calibrated range of bass frequencies. In another embodiment, the high pass filter module 60 may only remove audio signals falling within the calibrated range of bass frequencies if the amplitude of a respective audio signal is above a predetermined threshold value. The high pass filter module 60 may use a look-ahead routine or module to analyze segments of the streaming audio signal in advance of being sent to the amplifier 18.
In one embodiment, after a predetermined amount of time has been spent filtering the streaming audio signal, which may be created by a delay timer 66, the high pass filter module 60 checks to see if the operating temperature of the amplifier 18 is decreasing, which is illustrated at step 68. If the temperature of the amplifier 18 is not decreasing, at step 70, the high pass filter module 60 may increase a bandwidth value associated with the calibrated range of bass frequencies. For example, the high pass filter module 60 may start filtering frequencies between 20-80 Hz as opposed to an initial setting of 30-60 Hz. As such, the high pass filter module 60 is operable to adjustably filter bass frequencies contained in the streaming audio signal.
If the temperature value is decreasing, at step 72, the high pass filter module 60 determines if the temperature of the amplifier 18 is below a predetermined threshold value. The temperature value at which the high pass filter module 60 ceases filtering the streaming audio signal will vary depending upon the characteristics of each particular amplifier 18. Referring back to
Referring to
Once the appropriate bass audio signals are located, at step 84, the amplitude limiter module 80 adjusts the amplitude of the bass audio signals by lowering the effective amplitude of the bass audio signals. This decreases the amount of power consumed by the amplifier 18 thereby cooling the amplifier 18. The amount of amplitude adjustment that takes place may vary depending upon the design of the respective amplifier 18 and the temperature value of the amplifier 18. By way of example only, in one embodiment, the amplitude limiter module 80 may initially choose to reduce the amplitude of the bass audio frequencies by 25-35%.
The amplitude limiter module 80 also continuously monitors the temperature value of the amplifier 18, which is represented at step 86. If the temperature value of the amplifier 18 does not drop, at step 88, the amplitude limiter module 80 may increase a bandwidth value associated with the second calibrated range of bass frequencies. For example, the amplitude limiter may expand the second calibrated band of bass frequencies from 70-100 Hz to 70-120 Hz. In addition, the amplitude limiter module 80 also has the ability to increase the amount of amplitude reduction that occurs at step 84. As it relates the example set forth in the preceding paragraph, the amplitude limiter module 80 may adjust the amount of amplitude reduction from 25-35% to 35-45%, and so on. As such, the amplitude limiter module 80 is capable of reducing the amplitude of bass audio frequencies contained in the streaming audio signal and is capable of adjusting the range or bandwidth of frequencies it adjusts and the amount of amplitude adjustment that takes place.
If the temperature of the amplifier 18 is dropping, at step 90, the amplitude limiter module 80 determines if the temperature of the amplifier 18 has fallen below a predetermined threshold value, which, as previously set forth, the value of which varies depending upon the design of the amplifier 18. If the temperature of the amplifier 18 has not fallen below the predetermined threshold, the amplitude limiter module 80 continues to reduce the amplitude of bass frequencies falling within the second calibrated range of bass frequencies. Referring back to
The amplitude limiter module 80 may use an amplitude control algorithm to decrease or increase a bandwidth value associated with the calibrated range of bass frequencies. If the operating temperature of the amplifier 18 continues to rise above the upper threshold value after entering thermal management mode 54, the amplitude control algorithm is operable to gradually increase the bandwidth value of the calibrated range of bass frequencies. This causes the thermal management module 60 to further limit the amplitude value of the bass frequencies thereby causing the amplifier 18 to cool faster. Once the operating temperature of the amplifier 18 falls below a predetermined threshold value, the amplitude control algorithm begins stepping down the bandwidth of the frequencies that are reduced in amplitude until normal amplification resumes.
Referring to
As further illustrated in
The control unit 14 is capable of selectively activating and deactivating the adjustable bass frequency amplitude limiter circuit 102. The control unit 14 is also capable of adjusting a bandwidth value of the second calibrated range of bass frequencies for which the adjustable bass frequency amplitude limiter circuit 102 will reduce the amplitudes of bass audio signals contained in the analog streaming audio signal provided by the DSP 16. In addition, the control unit 14 is also capable of adjusting the amount of amplitude reduction being provided by the adjustable bass frequency amplitude limiter circuit 102. As with the previous embodiment, this provides the audio system 10 with an adjustment that allows the adjustable bass frequency amplitude limiter circuit 102 to increase or decrease the amount of frequencies contained in the second calibrated range of bass frequencies and also allows the amount of amplitude adjustment to be selectively increased or decreased.
Referring to
In thermal management mode, the control circuit 110 is capable of selectively engaging the adjustable high pass filter circuit 100 and/or the adjustable bass frequency amplitude limiter circuit 102 to perform their respective operations, which have been set forth above in great detail in connection with the detailed description of the other embodiments disclosed herein. As such, before the streaming analog audio signal reaches the amplifier 18, the streaming analog audio signal may have had certain bass frequencies filtered or removed by the adjustable high pass filter circuit 100 and/or had certain bass frequencies lowered in amplitude by the adjustable bass frequency amplitude limiter circuit 102. This embodiment of the present invention discloses an audio system 10 that comprises an all active analog/digital circuitry solution as opposed to a microprocessor based solution.
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One aspect of the present invention discloses a system comprising an audio source for selectively generating a streaming audio signal; a control unit connected with the audio source for receiving said streaming audio signal; a thermal sensor connected with an amplifier and having an output connected with the control unit, wherein the thermal sensor is operative to generate a temperature signal indicative of an operating temperature value of the amplifier; and a thermal management module executable by the control unit for controlling the amplifier in a thermal management mode that removes a calibrated range of bass frequencies from the streaming audio signal once the operating temperature value of the amplifier reaches an upper temperature threshold to thereby cool the amplifier. In yet another aspect, during the thermal management mode the thermal management module is operable to reduce an amplitude value of select audio signals in the streaming audio signal that fall within a second calibrated range of bass frequencies to a reduced amplitude value once the operating temperature value reaches the upper temperature threshold instead of, or in conjunction with, removing the calibrated range of bass frequencies.
Another aspect of the present invention discloses a method comprising means for monitoring a temperature value of at least one amplifier; means for entering a thermal management mode once the temperature value of the amplifier reaches an upper threshold, wherein the thermal management mode comprises: means for selecting a calibrated range of bass frequencies; and means for eliminating said calibrated range of bass frequencies from a streaming audio signal. In yet another embodiment, a second calibrated range of bass frequencies may be selected in conjunction with, or instead of, selecting the calibrated range of bass frequencies. In this embodiment, an amplitude value associated with select audio signals falling within the second calibrated range of bass frequencies is reduced by a predetermined amount.
Yet another aspect of the present invention discloses an amplifier comprising a control unit for receiving a streaming audio signal; a thermal sensor connected with the control unit and a heat dissipation member of the amplifier; and a high pass filter for selectively removing a calibrated range of bass frequencies from the streaming audio signal once the heat dissipation member of the amplifier reaches an upper threshold value. The amplifier may further include an amplitude limiter for limiting an amplitude value associated with select signals in the streaming audio signal that fall with a second calibrated range of bass frequencies. The amplitude limiter may be used in conjunction with the high pass filter or may be used by itself.
Another aspect of the present invention discloses a computer program product for use in an amplification system comprising computer executable program code for monitoring a temperature value of at least one amplifier; computer executable program code for entering a thermal management mode once said temperature value of said amplifier reaches an upper threshold, wherein said thermal management mode comprises: computer executable program code for selecting a first calibrated range of bass frequencies; and computer executable program code for eliminating said calibrated range of bass frequencies from a streaming audio signal. In alternative embodiments, the computer program product further comprises computer executable program code for selecting a second calibrated range of bass frequencies; and computer executable program code for computer executable program code for reducing an amplitude value of audio signals in said streaming audio signal that fall within said second calibrated range of bass frequencies.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.