WO2008117002A1

WO2008117002A1 - Active fan control

Info

Publication number: WO2008117002A1
Application number: PCT/GB2007/001090
Authority: WO
Inventors: Andrew Radford
Original assignee: Nds Limited
Priority date: 2007-03-26
Filing date: 2007-03-26
Publication date: 2008-10-02

Abstract

A system is described. The system includes a fan speed controller (12) to control speed of operation of at least one fan (14), the fan speed controller (12) receiving an input indicative of a volume measurement of audio being played by a device and adjusting the speed of operation of the at least one fan (14) as a function of the volume measurement. A related apparatus and methods are also described.

Description

ACTIVE FAN CONTROL

FIELD OF THE INVENTION

The present invention relates to a fan control system, specifically a fan control system for use in a consumer electronic device.

BACKGROUND OF THE INVENTION

Up until recently, set-top boxes, game consoles, audio video projectors, audio amplifiers, and other consumer electronic audio devices were completely solid state, and had no moving parts. All heat produced by the device was dissipated passively. In the last few years, consumer audio devices have become more advanced; consequently the power usage has increased and heat produced within the device enclosure has increased to the point that many have employed a ventilation and/or circulation fan to assist in ridding the device of surplus heat inside the case. The consequence of having a fan is the introduction of the noise created by the fan. The fan noise reduces the quality of the user experience, especially during quiet sections of audio, when the noise to signal ratio of the listening environment is effectively higher; i.e. the noise from the fan is more perceivable to the listener.

SUMMARY OF THE INVENTION

The present invention, in preferred embodiments thereof, seeks to provide an apparatus and methods for continuous and adaptive modulation of a fan speed to reduce disruption of an audio presentation on a consumer device that creates audio directly, that is part of a system that presents audio, or that is used in the vicinity of a system that presents audio. A fan speed controller, in a preferred embodiment of the present invention, may employ a continuous function whereby the speed of the fan at any point is based on the audio volume. An exemplary continuous function may comprise a proportional integral derivative (PID) function or any of its constituent parts. A further preferred embodiment of the present invention may comprise a temperature sensor input. The temperature sensor input may be used as an additional input to the continuous function to increase the fan speed if the temperature is above a predetermined threshold.

There is thus provided in accordance with a preferred embodiment of the present invention, a system including a fan speed controller to control speed of operation of at least one fan, the fan speed controller receiving an input indicative of a volume measurement of audio being played by a device and adjusting the speed of operation of the at least one fan as a function of the volume measurement. Additionally, in accordance with a preferred embodiment of the present invention, the input indicative of the volume measurement includes any one of the following a function proportional to the volume measurement, an integral function of the volume measurement, a function that is a derivative of the volume measurement, and a proportional integral derivative (PID) function of the volume measurement.

Moreover, in accordance with a preferred embodiment of the present invention, the system further includes a temperature sensor input for conveying a temperature measurement to the fan speed controller, wherein the fan speed controller is operative to further adjust the fan speed as a function of the temperature measurement. Further, in accordance with a preferred embodiment of the present invention, the fan speed controller is implemented in one of the following software, hardware, and a combination of software and hardware.

Still further, in accordance with a preferred embodiment of the present invention, the audio being played is provided by at least one of the following devices a set-top box, a television, a game console, a video projector, an audio-video projector, an audio amplifier, a stereo system component, a CD player, a DVD player, and a VHS player.

Additionally, in accordance with a preferred embodiment of the present invention, the input indicative of the volume measurement is provided to the fan speed controller by the device playing the audio.

Moreover, in accordance with a preferred embodiment of the present invention, the system further includes a microphone to measure the volume of audio being played and to provide the input indicative of the volume measurement to the fan speed controller.

Further, in accordance with a preferred embodiment of the present invention, the system further includes an environmental microphone to measure the volume of ambient noise and wherein the fan speed controller further adjusts the speed of operation of the at least one fan as a function of the ambient noise. Still further, in accordance with a preferred embodiment of the present invention, the at least one fan is comprised in at least one of the following devices a set-top box, a television, a game console, a video projector, an audio- video projector, an audio amplifier, a stereo system component, a CD player, a DVD player, and a VHS player.

There is thus provided in accordance with a preferred embodiment of the present invention, a method including receiving an input indicative of a volume measurement of audio being played by a device and adjusting speed of operation of at least one fan as a function of the volume measurement. Additionally, in accordance with a preferred embodiment of the present invention, the input indicative of the volume measurement includes any one of the following a function proportional to the volume measurement, an integral function of the volume measurement, a function that is a derivative of the volume measurement, and a proportional integral derivative (PID) function of the volume measurement.

Moreover, in accordance with a preferred embodiment of the present invention, the method further includes receiving a temperature measurement from a temperature sensor and further adjusting the speed of operation of the at least one fan as a function of the temperature measurement.

Further, in accordance with a preferred embodiment of the present invention, the audio being played is provided by at least one of the following devices a set-top box, a television, a game console, an audio projector, a video projector, an audio-video projector, an audio amplifier, a stereo system component, a CD player, a DVD player, and a VHS player.

Still further, in accordance with a preferred embodiment of the present invention, wherein the receiving an input indicative of the volume measurement is from the device playing the audio.

Additionally, in accordance with a preferred embodiment of the present invention, the method further includes measuring with a microphone the volume of audio being played and providing the input indicative of the volume measurement to the fan speed controller. Moreover, in accordance with a preferred embodiment of the present invention, the method further includes measuring a volume of ambient noise with an environmental microphone and adjusting the speed of operation of the at least one fan as a function of the ambient noise.

Further, in accordance with a preferred embodiment of the present invention, the at least one fan is comprised in at least one of the following devices a set-top box, a television, a game console, an audio projector, a video projector, an audio- video projector, an audio amplifier, a stereo system component, a CD player, a DVD player, and a VHS player. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more folly from the following detailed description, taken in conjunction with the drawings in which: Fig. 1 is a partially pictorial, partially block diagram illustration of usage of an exemplary fan control system in a consumer device operating in a non- limiting, home entertainment system, operative in accordance with a preferred embodiment of the present invention;

2A and 2B are exemplary graphical illustrations of the volume levels of an exemplary audio program and possible fan noise over time, operative in accordance with a preferred embodiment of the present invention; and

Fig. 3 is a more detailed block diagram illustration of the fan control system of Fig. 1 and components operably connected to it, operative in accordance with a preferred embodiment of the present invention.

It is noted that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Reference is now made to Fig. 1, which is a partially pictorial, partially block diagram illustration of usage of an exemplary fan control system in a consumer device operating in a non-limiting, home entertainment system, operative in accordance with a preferred embodiment of the present invention. A user 2 may, for example, be operating a home entertainment system comprising a television 4, a set-top box 6, and optional speakers 8A and 8B operatively connected. Set-top box 6 may comprise a fan control system 10 operably connected to a fan (not shown), operative in accordance with a preferred embodiment of the present invention. Audio may be provided by television 4, set- top box 6 and/or speaker(s) 8. Television 4 and speaker(s) 8 may be any appropriate television and speaker(s) known in the art. Set-top box 6 may be based on any appropriate set-top box known in the art, modified to comprise fan control system 10. Persons skilled in the art will appreciate that set-top boxes are named by their usual location on top of a television set, but that the term "set-top box" is not meant to limit the location of the set-top box relative to a television set with which the set-top box is associated, it being further appreciated that televisions with integrated set-top box functionality are also known in the art and are within the scope of the present invention.. Another non-limiting system may comprise an audio-video projector used with a stereo, wherein the projector produces the video and the stereo produces the audio. The audio-video projector may be any appropriate projector known in the art that comprises a fan control system operably connected to a fan and the stereo may be any appropriate stereo known in the art. Further non-limiting examples of consumer devices include appropriate game consoles and appropriate audio amplifiers known in the art. Other combinations of appropriate consumer devices which create audio directly or are part of a system that presents audio are within the scope of the present invention. Fan control system 10, which may be operably connected to a fan, may be used to control the operation of the fan in ridding the consumer device of surplus heat inside the device case. Fan control system 10 may modulate the fan speed in response to the sound level presently being presented by the consumer audio device(s) since generally the amplitude of audio presented is dynamic. The sound has loud and quiet periods. An example of a quiet period may be whispered dialogue, and an example of a loud period may be a car chase scene. During the generally quiet periods, the fan may be set to a low operating speed or even stopped. During the generally loud periods, the fan speed may be increased. With the knowledge of the sound level, the system may increase the fan speed during generally loud periods, to compensate for the quiet periods when the fan speed may be slower and the temperature inside the consumer device case may have risen. During the loud periods, although the fan speed may be higher, the noise from the fan may be essentially masked by the program audio.

Figs. 2A and 2B, to which reference is now made, are exemplary graphical illustrations of the volume levels of an exemplary audio program and possible fan noise over time. In Fig. 2A a constant fan speed may be used, which may result in a constant fan noise level. The fan noise level does not change with the audio level and hence at various times when the audio program level is relatively quiet the noise of the fan may be invasive to the listener. For example, at point A the fan noise may be greater than the audio volume, which may cause the audio to be inaudible to the listener. However, even at point AA the fan noise may be intrusive to the listener. At point B the audio volume is greater than the fan noise and hence the fan noise may be less noticeable.

In Fig. 2B the same audio program level is used but the fan noise level is constantly changing. As may be seen in Fig. 2B, the fan noise level is generally less that of the audio program level. The fan noise level may be decreased as the audio level decreases and may be increased as the audio level increases. Hence, at point C, even though the audio is at a relatively low volume, the fan noise may have been decreased to an even lower level, for example, by lowering the fan speed. At point D, despite the fan noise being greater than the constant noise level of Fig. 2A, the noise may be masked by the high audio volume at that point. The changing of the fan speed during periods of quiet audio is possible as long as the consumer device temperature is within safe operating limits. During the lowered fan speed periods, the device temperature inside the consumer device may increase, but it will do so relatively slowly. The fan speed may be increased above the regular operating speed during the noisy times to make up for the slow fan speed periods and thus the increased speed may hasten the time to cool the device down.

In a further preferred embodiment of the present invention, if the temperature is above a pre-set maximum the fan speed reduction method may be adapted to bias the control system in favor of a temperature component to keep the device within safe thermal operating limits. At point E, in the further preferred embodiment of the present invention, the fan noise level may approach or be greater than the audio level if the temperature in the device is sufficiently hot, for example, if the temperature is above a predetermined value. This will be explained in further detail hereinbelow with respect to Fig. 3.

Fig. 3, to which reference is now made, is a more detailed block diagram illustration of fan control system 10 (Fig. 1) and components operably connected to it, operative in accordance with a preferred embodiment of the present invention. Fan control system 10 may comprise a speed controller 12. Fan control system 10 may receive an input related to audio volume and an optional temperature input, and may produce an output to control the operation of a fan. Speed controller 12 may be operably connected to a fan 14 via a fan driver 20. Speed controller 12 may be operably connected to an audio volume sense unit 16 and to an optional temperature sensor 18.

Audio volume sense unit 16 may be implemented in various ways to output the present volume of the audio. In a preferred embodiment of the present invention, audio volume sense unit 16 may have direct access to the digital audio being processed by the audio decoder and hence the volume of the audio. In a preferred embodiment of the present invention, audio volume sense unit 16 may use a microphone (not shown) to measure the volume of audio being played. Audio volume sense unit 16 may sample the analog audio output volume detected by the microphone and may encode the analog signal to a digital representation to obtain the input indicative of the volume measurement. A microphone may be used, for example, if the consumer device has no direct access to the level of the audio it is presenting and/or for consumer devices used in conjunction with an audio device; non-limiting examples include an audio projector used with a stereo and a set-top box used with a television and speaker.

In a further preferred embodiment of the present invention, an environmental microphone (not shown) may be used to measure the volume of ambient noise. Audio volume sense unit 16 may sample the ambient noise detected by the environmental microphone and may provide an output to fan speed controller 12 to enable adjustment of the fan speed as a function of the ambient noise.

Fan speed controller 12 controls fan 14 depending on the input of audio volume sense unit 16, which reflects the level of the audio volume. In a preferred embodiment of the present invention, fan speed controller 12 may be implemented as a software based control algorithm. Fan speed controller 12 may set the speed of fan 14 as a function of the audio volume level.

In determining the desired fan speed given an analog audio signal, fan speed controller 12 may pass the analog audio signal through a low-pass filter comprising a sufficient time constant to produce a signal representative of a loud or quiet period as may be "perceived by a listener". An exemplary, sufficient time constant may be 2-3 seconds, as loud and/or quiet periods as "perceived by a listener" may have a similar time scale. A time constant of 2-3 seconds may also be approximately the same order of time needed to effectively change the RPM (revolutions per minute) speed of a typical appropriate fan available in the present art. For example, set-top boxes usually have 30-80 mm case fans, which may go from stopped to full speed in less than 3 seconds. In the case of a digital audio signal, in determining the desired fan speed, the digital signal may be averaged by fan speed controller 12 to suit the time scale(s) of fan speed controller 12. The representative signal of the loud or quiet period may then be put through a control function and the result may be output to optional fan driver 20 by means of a device driver interface. Control functions are explained in further detail hereinbelow. In an exemplary control function the resultant fan speed signal may be the representative signal (of a loud or quiet period) multiplied by some constant.

In a further preferred embodiment of the present invention, the control system may be implemented at the device driver level, with no exposure to high level software running on the consumer device. For example, the control function may be implemented in the system level code (firmware) of the device (for example a set-top box). This implementation may allow the control system software to operate all the time and may not allow higher level software (for example application software) to disrupt this control function. Fan driver 20 may be used to interface between fan speed controller

12 and fan 14. Fan driver 20 may comprise power circuitry to convert the signal from fan speed controller 12 to a signal that is compatible with fan 14 and may be sufficient to power the fan at various speeds (e.g. various RPM). In the exemplary case of a 'simple' low-cost fan a voltage signal from about 5V to 12V may be required. At 5 V the fan may be at minimum speed, at 12V the fan may be at maximum speed, and at 0 volts the fan may be stopped. The voltage supply must be capable of supplying enough electrical current to satisfy the fan at any point in the 5- 12V range.

Fan 14 may be any appropriate fan (for hot air exhaust, such as a case fan) and/or may include any fans in the system which contribute to the noise of the system and can have speed reduced for a short period of time without detrimental effect due to the heat increase that may result. Fan 14 may comprise fans mounted within the consumer device case, for example, on hot components. Fan 14 may comprise any appropriate fan(s) known in the art. For example, there exist in the art commercially available case fans that are able to be speed controlled. There further exist commercially available case fans that have a feedback mechanism to give the controlling system a measurement of the present fan RPM; this would allow greater control over the true fan RPM.

In a preferred embodiment of the present invention, the amplitude of the audio may be derived from the digital audio signal presently being output by the consumer device. The consumer device may monitor the audio signal and if the device has the capability the audio signal level may be obtained by the device directly from the audio decoder while it is still in the digital domain. If the amplitude is obtained in the digital domain less hardware may be required. The audio signal may be explicitly monitored by a software loop or automatically via an interface to the digital audio decoder hardware. The digital audio signal may be averaged to suit the time scale(s) of the fan control.

The control function implemented by fan speed controller 12 may translate audio volume levels to fan RPM. In a non-limiting example, the control function may be a PID function or a subset thereof. PID functions are well known in the art. A PID function may calculate the fan speed from three aspects of the audio signal: proportional, integral, and derivative. The proportional term provides a weighting proportional to the present audio volume, for example, the greater the audio volume, the louder the fan noise may be without degrading the listening experience and hence the faster the fan speed may be set. The integral term may relate to how long the audio level has been high/low, for example, if the audio volume has been low for a while, then the present fan speed based on the proportional control only may not be adequate enough to reduce heat, therefore the speed may need to be increased further. The derivative term may relate to the rate of change, for example, if the audio volume is changing very quickly then the fan speed may be changed more quickly than previously to be more reactive to these sudden changes. Thus, the fan speed controller of the present invention may take advantage of the thermal inertia of the device to synchronize exhaust fan cooling cycles with the loud periods of the program audio to the extent possible while maintaining a temperature within thermal operating limits for the consumer device.

In a further preferred embodiment of the present invention, fan speed controller 12 may receive input from optional temperature sensor 18; this input may allow the addition of temperature related terms (possibly weighted) to the control function. The addition of temperature sensor 18 would enable fan speed controller 12 to be aware of the temperature in the consumer device, in order to ensure that the system temperature stays within safe operating limits. In a situation in which the system temperature is such that any reduction in air circulation would result in a temperature increase above the safe operating limit the strategy of slowing down of the fan in the quiet periods could be suspended. In this case the noise level produced due to the suspension of fan speed reduction may be no worse than a normal system with thermal or constant speed fan control.

In a further embodiment of the present invention, fan speed controller 12 may be implemented in hardware in an analog domain. Fan speed controller 12 may receive an analog signal from audio volume sense unit 16 and optionally from temperature sensor 18 and create an analog output signal for fan speed driver 20. In a still further embodiment of the present invention, fan speed controller 12 may be implemented in hardware in a digital domain. However in the digital domain, even when the fan speed controller is implemented in hardware, software is generally also used. An implementation comprising any appropriate combination of hardware and software is within the scope of the present invention.

In a further preferred embodiment the fan speed controller may comprise an on and/or off function, whereby the fan may be shut off if the audio is below a predetermined level. Such an embodiment may comprise a temperature sensor input, which may be used as a "failsafe" mechanism providing an override of the off function of the fan speed controller.

Numerous specific details have been described in the preceding description to provide a thorough understanding of the invention. However, it will be understood by those of ordinary skill in the art that the present invention may not require all these specific details. In other instances, well-known methods, and/or components may not have been described in full detail so as not to obscure the present invention.

An embodiment of the present invention may include an apparatus for performing the operations described herein. Such an apparatus may be specially constructed or may comprise a general-purpose computer that is operated according to a computer program stored therein. Such a computer program may be stored in any appropriate computer readable storage medium.

It is appreciated that software components of the present invention may, if desired, be implemented in ROM (read only memory) form. The software components may generally be implemented in hardware, if desired, using conventional techniques.

It is appreciated that various features of the invention, which are, for clarity, described in the contexts of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It should therefore be understood that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the invention is defined only by the claims that follow:

Claims

1. A system comprising: a fan speed controller to control speed of operation of at least one fan, said fan speed controller receiving an input indicative of a volume measurement of audio being played by a device and adjusting the speed of operation of the at least one fan as a function of the volume measurement.

2. The system according to claim 1 and wherein the input indicative of the volume measurement comprises any one of the following: a function proportional to the volume measurement; an integral function of the volume measurement; a function that is a derivative of the volume measurement; and a proportional integral derivative (PID) function of the volume measurement.

3. The system according to either of claims 1 and 2 and further comprising a temperature sensor input for conveying a temperature measurement to said fan speed controller, wherein said fan speed controller is operative to further adjust the fan speed as a function of said temperature measurement.

4. The system according to any of claims 1 - 3 and wherein said fan speed controller is implemented in one of the following: software; hardware; and a combination of software and hardware.

5. The system according to any of claims 1 - 4 and wherein the audio being played is provided by at least one of the following devices: a set-top box; a television; a game console; a video projector; an audio-video projector; an audio amplifier; a stereo system component; a CD player; a DVD player; and a VHS player.

6. The system according to any of claims 1 - 5 and wherein the input indicative of the volume measurement is provided to said fan speed controller by the device playing the audio.

7. The system according to claims 1 - 6 and further comprising a microphone to measure the volume of audio being played and to provide the input indicative of the volume measurement to said fan speed controller.

8. The system according to any of claims 1 - 7 and further comprising an environmental microphone to measure the volume of ambient noise and wherein said fan speed controller further adjusts the speed of operation of the at least one fan as a function of the ambient noise.

9. The system according to any of claims 1 - 8 and wherein the at least one fan is comprised in at least one of the following devices: a set-top box; a television; a game console; a video projector; an audio-video projector; an audio amplifier; a stereo system component; a CD player; a DVD player; and a VHS player.

10. A method comprising: receiving an input indicative of a volume measurement of audio being played by a device ; and adjusting speed of operation of at least one fan as a function of the volume measurement.

11. The method according to claim 10 and wherein the input indicative of the volume measurement comprises any one of the following: a function proportional to the volume measurement; an integral function of the volume measurement; a function that is a derivative of the volume measurement; and a proportional integral derivative (PID) function of the volume measurement.

12. The method according to either of claims 10 and 11 and further comprising: receiving a temperature measurement from a temperature sensor; and further adjusting the speed of operation of the at least one fan as a function of the temperature measurement.

13. The method according to any of claims 9 - 12 and wherein the audio being played is provided by at least one of the following devices: a set-top box; a television; a game console; an audio projector; a video projector; an audio- video projector; an audio amplifier; a stereo system component; a CD player; a DVD player; and a VHS player.

14. The method according to any of claims 9 - 13 and wherein said receiving an input indicative of the volume measurement is from the device playing the audio.

15. The method according to claims 9 - 14 and further comprising measuring with a microphone the volume of audio being played and providing the input indicative of the volume measurement to the fan speed controller.

16. The method according to any of claims 9 - 15 and further comprising: measuring a volume of ambient noise with an environmental microphone; and adjusting the speed of operation of the at least one fan as a function of the ambient noise.

17. The method according to any of claims 9 - 16 and wherein the at least one fan is comprised in at least one of the following devices: a set-top box; a television; a game console; an audio projector; a video projector; an audio- video projector; an audio amplifier; a stereo system component; a CD player; a DVD player; and a VHS player.