WO2008104026A1

WO2008104026A1 - Heat protection system for a heat sensitive device

Info

Publication number: WO2008104026A1
Application number: PCT/AU2008/000258
Authority: WO
Inventors: George Forster-Jones; Willy Nelissen
Original assignee: Thor Technologies Pty Ltd
Priority date: 2007-02-28
Filing date: 2008-02-28
Publication date: 2008-09-04

Abstract

A heat protection system (10) for a heat sensitive device (100) comprising means for detecting a discontinuance in supply of power to the heat sensitive device from a main power source (30) and cooling means (20) for cooling heat sensitive components (102) housed within the heat sensitive device (100) on detection of a discontinuance. The heat protection system (10) is ideally suited for protecting the globe (102) of a projector (100).

Description

"HEAT PROTECTION SYSTEM FOR A HEAT SENSITIVE DEVICE" FIELD OF THE INVENTION

The invention relates to a heat protection system. The invention is particularly suited to managing the cool-down process for a projector globe in the event of power failure.

BACKGROUND TO THE INVENTION

The following discussion of the background to the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was published, known or part of the common general knowledge in any jurisdiction as at the priority date of the application.

The light globe used in a projector is a device that generates a significant amount of heat. At the same time, a failure to control the temperature of the light globe can cause serious damage to the filament contained in the globe. In extreme cases, the heat generated by the light globe may be sufficient to burn out the filament.

It is for this reason that projectors include vents to allow hot air to escape the light globe enclosure. Commonly, a fan is also employed to assist in regulating the temperature of the light globe during operation.

The flaw in this system is that in order for the fan to operate, the projector must be receiving mains power. In the event of a power failure - for whatever reason - the fan stops and the globe is turned off. However, while the globe may no longer be on and thus producing heat at the same level as it was previously, the globe will still emanate heat until cooled. This heat remains substantially trapped within the light globe enclosure and is thereby able to do damage to the filament of the light globe.

One previous solution to this problem has been to install an uninterrupted power supply (a UPS) to maintain power to the projector in the event of power failure, so that the projector may be safely turned off. However, this solution presents difficulties in that the UPS must be correctly sized to the power draw of the projector. Furthermore, in the case of ceiling mount projectors, it is not really possible to install a UPS due to weight and aesthetic requirements. The use of a UPS can also be a flawed solution in situations where there are no other objects which can give an indication of power failure. In such situations, the UPS then merely continues to provide power to the projector until the power stored by the UPS runs out - at that point in time, due to the projector not having been shut down in the meantime, the projector suffers the same problems as if a UPS had not been installed.

A similar situation exists in relation to other heat sensitive products. In circumstances when the power has failed, the inability of the product to properly cool down can either reduce the lifespan of the product or cause it to fail completely..

It is therefore an object of the present invention to provide a heat protection system that manages the power failure state of a heat sensitive device in a way that either reduces in some manner the adverse effects of the power failure or to extend the period of time following a power failure before such adverse effects take effect.

SUMMARY OF THE INVENTION

Throughout this document, unless otherwise indicated to the contrary, the terms "comprising", "consisting of, and the like, are to be construed as non-exhaustive, or in other words, as meaning "including, but not limited to".

In accordance with a first aspect of the invention there is a heat protection system for a heat sensitive device comprising:

means for detecting a discontinuance in supply of power to the heat sensitive device from a main power source; and

cooling means for cooling heat sensitive components housed within the heat sensitive device on detection of a discontinuance.

The cooling means ideally takes the form of a fan which is supplied power by a secondary power store on detection of the discontinuance. Alternatively, the cooling means may take the form of a heat sink, liquid cooling system or heat pipe.

The secondary power store may take a variety of forms. In its most preferred form, the secondary power store takes the form of rechargeable batteries. When using rechargeable batteries as the secondary power store, it is preferable that a housing in which the secondary power store is housed be externally accessible to allow the rechargeable batteries to be changed or removed as required. Alternatively, the secondary power store may take the form of capacitors.

A low power alarm may also be used to indicate to the owner of the heat sensitive device when the secondary power store is low in power. The alarm may be audible or visual in nature.

The means for detecting a discontinuance in power supply ideally further includes means for verifying that a discontinuance is in effect and that a power fluctuation event has not caused a temporary discontinuance.

Similarly, the means for detecting a discontinuance in power supply may include processing means to ensure that the heat protection system operates once and once only for each discontinuance.

In a preferred embodiment, the cooling means is configured to operate for a set period of time following detection of a discontinuance. This period of time may be a hardwired time period or an adjustable time period determined by the current settings of a series of dip switches or the like. The mechanisms by which these time periods are tracked may take the form of count-down routines controlled by a processing means or mechanical timers.

The heat protection system may also include means for detecting a resumption of power following a discontinuance. Means for detecting a resumption is operably connected to the cooling means so as to prevent unnecessary operation of the cooling means following resumption of mains power.

The heat protection system may operate as a separate, self contained unit. Alternatively it may be integrated with the heat sensitive device. In its preferred embodiment as a self contained unit, the protection system is positioned so that either:

the heat protection system forces cool air into the heat sensitive device through at least a portion of one air intake port; OR

the heat protection system draws hot air out of the heat sensitive device through at least a portion of one air outtake port.

To ensure maximum efficiency in its operation, a heat protection system operating as a self-contained unit ideally forms an air-tight seal with the air intake port or air outtake port (as appropriate). The heat protection system may also operate to provide further protection to the heat sensitive device by way of inclusion of under- and over- voltage protection means and/or power filtration systems. In the case of under- and over- voltage protection means, external alarms may be provided to indicate whether the heat sensitive device is receiving under-volted or over-volted power. Again, these alarms may be audible or visual in nature.

Due to the wide variety of heat sensitive devices to which a stand alone heat protection system in accordance with this aspect of the invention may need to operate with, the heat protection system may further include a mounting plate. The mounting plate is adapted to be securely fixed to the heat protection system and the mounting componentry of the heat sensitive device in such a manner that the heat protection system and heat sensitive device are fixed in position relative to each other. It should be appreciated, however, that other mounting systems could be used to achieve this same effect.

Furthermore, in its most preferred embodiment, the heat sensitive device obtains power from the main power source by way of the heat protection system.

The heat protection system may further include a temperature sensor, the cooling means operable to cool the heat sensitive components on the temperature sensor exceeding a predetermined temperature value irrespective of the operational state of the heat sensitive device. This then allows the heat protection system to provide additional protection to an operational heat sensitive device during times of extreme high temperatures.

Ideally, the heat sensitive device is a projector and the heat sensitive components include the globe of the projector.

In accordance with a second aspect of the present invention there is a method for protecting a heat sensitive device comprising the steps of :

determining if there has been a discontinuance in supply of power to the heat sensitive device from a main power source; and

cooling heat sensitive components housed within the heat sensitive device on detection of a discontinuance. Preferably, the step of cooling the heat sensitive components includes the sub-step of supplying power to a fan from a secondary power store.

The method may further include the step of activating an alarm when the secondary power store is low in power.

To prevent unnecessary action taking place, the method may also include the step of verifying that a discontinuance is in effect prior to initiating the step of cooling the heat sensitive components. The method may also include the step of monitoring the discontinuance to ensure that the step of cooling the heat sensitive components is initiated only once per discontinuance.

Ideally, the step of cooling the heat sensitive components includes the sub-steps of initiating a timer upon commencement of cooling of the heat sensitive components and stopping the cooling of the heat sensitive components on the timer reaching a predetermined value.

The protection method may further include the steps of detecting a resumption of power following a discontinuance and stopping the cooling of the heat sensitive components on detection of the resumption of power.

In one preferred embodiment, the protection method also includes at least one of the steps of:

filtering the power supplied by the main power source;

detecting the supply of under-volted power by the main power source to the heat sensitive device and initiating an alarm on such detection; AND/OR

detecting the supply of over-volted power by the main power source to the heat sensitive device and initiating an alarm on such detection.

The protection method may further include the step of cooling the heat sensitive components when a temperature sensor exceeds a predetermined temperature value irrespective of the operational state of the heat sensitive device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of a projector having a protection system of a first embodiment of the present invention mounted thereto.

Figure 2 is a wiring schematic of a protection system of a second embodiment of the present invention.

PREFERRED EMBODIMENTS OF THE INVENTION

In accordance with a first embodiment of the invention there is a heat protection system 10 for a globe 102 of a projector 100. In this embodiment, the projector 100 is a ceiling mountable home theatre projector.

The heat protection system 10 forms a self-contained unit mounted to the projector 100. The protection system 10 comprises control circuitry 12, a power supply 14, a transformer 16, a power store 18 and a fan 20. The control circuitry 12 includes a microprocessor 22.

The heat protection system 10 is mounted to the projector 100 in such a manner as to cover at least one air intake vent 104 of the projector 100 provided for cooling of the globe 102. In this embodiment, the heat protection system 10 is fixed in position relative to the projector 100 by way of an adaptor plate 24.

The adaptor plate 24 comprises a mounting flange 26 and a positioning flange 28. The mounting flange 26 has apertures provided therein substantially corresponding to the mounting apertures of the projector 100. In this manner, the mounting flange 26 is sandwiched in between the projector 100 and the ceiling mount 106 when the projector 100 is secured to the ceiling mount 106 by way of threaded screws (not shown). The positioning flange 28 is adapted to receive the protection system 10 and position it in such a manner as to provide an air-tight seal between the protection system 10 and the at least one air intake vent 104 when the mounting flange 26 is received between the projector 100 and the ceiling mount 106.

It is important, but not essential, that the seal between the at least one air intake vent 104 and the projection system be air-tight as the loss of air being forced through the at least one air intake vent 104 by the fan 20 affects the performance of the heat protection system 10 in cooling the globe 102. The power supply 14 accepts mains power by way of mains plug 30. Mains plug 30 is connected to the same outlet as the projector 100 (for example, by way of a double adaptor plug). Mains power received by way of mains plug 30 is transformed by the transformer 16 from an AC voltage to a DC voltage (in the range of 0-5v) as would be known to the person skilled in the art.

The transformed voltage is supplied to the power store 18 and the control circuitry 12. The transformed voltage supplied to the power store 22 is used to recharge the power store 22, in this case a pair of 9v rechargeable batteries. The power store 22 and power supply 14 are in parallel to each other so as to allow the power store 22 to supply power to the heat protection system 10 in place of the power supply 14 in the event of power failure.

As mentioned above, the control circuitry 12 includes a microprocessor 22. The microprocessor 22 monitors the source of its power. If the microprocessor 22 detects that its power is now being sourced from the power store 22 it sets up a first countdown timer routine. On completion of the first countdown timer routine, the microprocessor 22 again checks whether its power is being sourced from the power store 22. If this is the case, the microprocessor 22 determines that a mains power failure has occurred.

On determining that a mains power failure has occurred, the microprocessor 22 directs power to the fan 20 while at the same time commencing a second countdown timing routine. In this embodiment, the second timing countdown routine lasts for fifteen minutes.

With power directed to it, the fan 20 forces air towards the at least one air intake valve 104 and thereby assists in cooling the globe 104.

On completion of the second countdown routine, the microprocessor 22 ceases directing power to the fan 20 and shuts itself down. By shutting itself down, the power store 18 is not drained of further power.

In accordance with a second embodiment of the invention, where like numerals reference like parts, there is a heat protection system 200 for a projector 100. The heat protection system 200 is substantially identical to the heat protection system 10 described in the first embodiment of the invention, but with the addition of an under- and over- voltage shutdown systems. This is important as under-volting or over-volting the projector places stress on the projector 100 as a whole, which may lead to permanent damage.

In order to provide this functionality, the transformer 16 is replaced with a voltage reducing network 202. The voltage reducing network 202 similarly transforms the AC mains power to a DC voltage somewhere in the range of 0-5v. At the same time, some filtration and regulation of the power is undertaken by the voltage regulator 208.

In addition to the operations of the microprocessor 22 as described in the first embodiment of the invention, the microprocessor 22 also operates to determine the DC voltage of the power supplied by way of the voltage reducing network 202. In doing so, the 0-5v range of the power is mapped to a 0-255 numeric value (thus the microprocessor 22 is able to determine the power to within approx. 0.02v). The mapped numeric value is then compared by the microprocessor 22 against a high volt value (representative of over-volting) and a low volt value (representative of under- volting). If the mapped numeric value exceeds the high volt value, the microprocessor 22 operates to light up an over volt indicator 204 on the protection system 10. If the mapped numeric value is below the low volt value, the microprocessor 22 operates to light up an under volt indicator 206 on the protection system 10. In either event, the microprocessor 22 further operates to shut off power to the projector 100 provided by way of relay 206.

It should be appreciated by the person skilled in the art that the above invention is not limited to the embodiment described. In particular, the following modifications and improvements may be made without departing from the scope of the present invention:

• The heat protection system 10 may be further modified to include at least one dip switch. Operators may then change the at least one dip switch to a setting which represents the amount of time that the fan 20 should run following a power failure. In this manner, the heat protection system 10 may preserve the power store 18 when used to protect a globe 102 having a shorter cool-down period than the factory set run-time for the fan 20.

• The heat protection system 10 could be reversed such that the fan 20 is used to draw hot air out through at least one outlet vent which it covers. In yet a further alternative, the heat protection system 10 may be operated using two fans, one to draw cool air in through the at least one inlet vent which it covers and one to draw hot air out through at least one outlet vent which it also covers.

• The adaptor plate 24 may be sold as a separate unit to the protection system 10. In this manner, the heat protection system 10 may be manufactured as a generic component while the adaptor plate 24 is customised to meet the requirements of the projector 100 to which the heat protection system 10 is to be attached.

• The adaptor plate 24 may be omitted. In its place other forms of connecting the heat protection system 10 to the projector 100 may be used. For instance, the heat protection system 10 may use clips to attach itself to the air intake vent 104 or the air outlet vent as appropriate. Alternatively, and particularly in the case of desktop projectors, the heat protection system 10 may be able to work sufficiently merely by being positioned right against the at least one intake vent 104.

• The first countdown timer routine is ideally set to elapse after between 700 to 800 milliseconds, but other time periods may be used. In this manner, short power fluctuations do not trigger operation of the heat protection system 10.

β The heat protection system 10 may be modified to include an IEC connector in place of mains plug 30. In such a configuration, for projectors 100 that do not come with an integrated power cable, the power cable of the projector 100 can be used to supply power to the heat protection system 10. Power is then on- supplied to the projector 100 by way of the IEC connector and the relay 206. This configuration also does away with the requirement for a double adaptor to power both the projector 100 and the heat protection system 10.

• The heat protection system 10 may be further modified to allow the microprocessor 22 to cease directing power to the fan 20 if power is restored to the projector 100 before completion of the second countdown routine.

• The power store 16 may take, for example, the form of rechargeable batteries or capacitors. Furthermore, a low power indicator or alarm may be incorporated into the heat protection system 10 to advise of situations where the protection system 10 may not be able to adequately protect the projector 100 in the event of power failure. In this situation, and where the power store 16 takes the form of batteries (rechargeable or otherwise), the batteries that form the power store 16 may be contained in a removable or externally accessible housing. The batteries can then be changed on activation of the low power indicator or alarm or removed in situations where the projector 100 will not be used for an extended period of time (such as while the occupants of the premises in which the projector 100 is installed are on holidays).

• In an alternative arrangement, the microprocessor 22 may continue to draw power from the power store 16 following completion of the second countdown timer routine. In such an arrangement, to allow the microprocessor 22 to distinguish between a new power failure and a continuing power failure, the microprocessor 22 may use a flag variable. On determination of a power failure, the microprocessor 22 would operate to set the flag variable to a first value. On subsequent determination that power has been restored to the projector 100, the microprocessor 22 would operate to set the flag variable to a second value. Thus, the microprocessor 22 would not only check at the end of the first countdown timer routine whether power is not being supplied by way of mains power, but will also check the status of the flag variable before directing power to the fan 20.

• The heat protection system 10 may be implemented as an integral component of the projector 100.

• The fan 20 may be replaced by other cooling systems such as a heat pipe, heat sink or by way of liquid cooling.

• The countdown timing routines initiated by the processor may be replaced with mechanical timers that are initiated and reset by the processor 22 or control circuitry 12.

• The heat protection system 10 may include a temperature sensor. On the temperature sensor determining that the temperature of the projector 102 exceeds a predetermined temperature value, the microprocessor 22 operates to provide power to the fan 20.

• Additionally, while the invention has been described in the context of a heat protection system 10 for a projector 100, the invention is not limited to such use. The invention can just as easily be adapted to protect heat sensitive components of other heat sensitive devices such as high-end amplifiers, LCD televisions and CRT televisions.

It should be further appreciated by the person skilled in the art that the features described above, where not mutually exclusive, can be combined to form yet further embodiments of the invention.

Claims

We Claim:

1. A heat protection system for a heat sensitive device comprising:

2. A heat protection system according to claim 1 , where the cooling means is supplied with power by a secondary power store on detection of the discontinuance.

3. A heat protection system according to claim 2, where the cooling means is one or more of the following: a fan; a heat sink; a liquid cooling system; a heat pipe.

4. A heat protection system according to claim 2 or claim 3, where the secondary power store is a set of rechargeable batteries.

5. A heat protection system according to claim 4, where the set of rechargeable batteries are housed in an externally accessible housing.

6. A heat protection system according to claim 2 or claim 3, where the secondary power store is a set of capacitors.

7. A heat protection system according to any one of claims 2 to 6 including a low power alarm to indicate when the secondary power store is low in power.

8. A heat protection system according to any preceding claim, where the means for detecting a discontinuance ^• in power supply ideally further includes means for verifying that a discontinuance is in effect and that a power fluctuation event has not caused a temporary discontinuance.

9. A heat protection system according to any preceding claim, where the means for detecting a discontinuance in power supply also includes processing means to ensure that the heat protection system operates once and once only for each discontinuance.

10. A heat protection system according to any preceding claim, where the cooling means is configured to operate for a set period of time following detection of a discontinuance.

1 1 . A heat protection system according to claim 10, where the set period of time is a hardwired time period.

12. A heat protection system according to claim 10, where the set period of time is an adjustable time period.

13. A heat protection system according to claim 12, where the set period of time is determined by the current settings of a series of dip switches.

14.A heat protection system according to any preceding claim, further including means for detecting a resumption of power following a discontinuance, the means for detecting a resumption being operably connected to the cooling means so as to prevent unnecessary operation of the cooling means following resumption of mains power.

15. A heat protection system according to any preceding claim, where the heat protection system is a separate, self contained unit relative to the heat sensitive device.

16. A heat protection system according to claim 15, where the heat protection system forces cool air into the heat sensitive device through at least a portion of one air intake port.

17. A heat protection system according to claim 15 or claim 16, where the heat protection system draws hot air out of the heat sensitive device through at least a portion of one air outtake port.

18. A heat protection system according to any one of claims 16 to 17, where the heat protection system is positioned during operation in a manner to form an air tight seal with the air intake port, air outtake port or both, as appropriate.

19. A heat protection system according to any one of claims 15 to 18, further including a mounting plate adapted to be securely fixed to the heat protection system and at least a portion of the heat sensitive device or the mounting componentry of the heat sensitive device.

20. A heat protection system according to any one of claims 1 to 14, where the heat protection system is integrated into the heat sensitive device.

21. A heat protection system according to any preceding claim, further including means for determining whether the heat sensitive apparatus is under-volted or over-volted and to display an external alarm accordingly.

22.A heat protection system according to any preceding claim, where the heat sensitive device obtains power from the main source by way of the heat protection system.

23.A heat protection system according to any preceding claim, further including a temperature sensor, the cooling means operable to cool the heat sensitive . components on the temperature sensor exceeding a predetermined temperature . value irrespective of the operational state of the heat sensitive device.

24.A heat protection system according to any preceding claim, where the heat sensitive device is a projector and the heat sensitive components include the globe of the projector.

25.A method for protecting a heat sensitive device comprising the steps of:

cooling heat sensitive components housed within the heat sensitive device on detection of a discontinuance.

26.A method for protecting a heat sensitive device according to claim 25, where the step of cooling the heat sensitive components includes the sub-step of supplying power to a fan from a secondary power store.

27.A method for protecting a heat sensitive device according to claim 26, the method further including the step of activating an alarm when the secondary power store is low in power.

28.A method for protecting a heat sensitive device according to any one of claims 25 to 27, the method further including the step of verifying that a discontinuance is in effect prior to initiating the step of cooling the heat sensitive components.

29.A method for protecting a heat sensitive device according to any one of claims 25 to

28, the method also including the step of monitoring the discontinuance to ensure that the step of cooling the heat sensitive components is initiated only once per discontinuance.

30. A method for protecting a heat sensitive device according to any one of claims 25 to

29, where the step of cooling the heat sensitive components includes the sub-steps of initiating a timer upon commencement of cooling of the heat sensitive components and stopping the cooling of the heat sensitive components on the timer reaching a predetermined value.

31.A method for protecting a heat sensitive device according to any one of claims 25 to 29, where the method further includes the steps of detecting a resumption of power following a discontinuance and stopping the cooling of the heat sensitive components on detection of the resumption of power.

32.A method for protecting a heat sensitive device according to any one of claims 25 to 31 , the method further including at least one of the steps of:

filtering the power supplied by the main power source;

33.A method for protecting a heat sensitive device according to any one of claims 25 to 32, the method also including the step of cooling the heat sensitive components when a temperature sensor exceeds a predetermined temperature value irrespective of the operational state of the heat sensitive device.

34.A heat protection system substantially as described herein with reference to the drawings.

35.A method for protecting a heat sensitive device substantially as described herein with reference to the drawings.