GB2513841A

GB2513841A - Temperature-controlled computing device

Info

Publication number: GB2513841A
Application number: GB1307420.8A
Authority: GB
Inventors: Howard Gould; Graham Soper; Jonny Dunning
Original assignee: Isis Technology Ltd
Current assignee: Isis Technology Ltd
Priority date: 2013-04-24
Filing date: 2013-04-24
Publication date: 2014-11-12
Also published as: GB201307420D0

Abstract

A device comprises a display having a light source and a main processing module arranged to provide a display signal to the display. A level of power supplied to the light source is managed based on a measured temperature. In one example, the method includes, in response to activation of the computer device, initiating supply of power to the display light source at a first time; measuring a temperature in the device after the first time; in response to the temperature attaining a predetermined threshold R1-R6 at a second time, activating the main processing unit; and providing a display signal to the display by the main processing unit after activation. Alternatively a method for powering up, and managing the temperature of, a computing device is described. Preferably the device includes a heater, a fan and/or a heat sink. The construction of the device may include a hinge (fig. 9) having spring loaded pins (87, 88), guide rails (85) and bearing tracks (84).

Description

Temperature-controlled computing device The present invention relates to computing devices, and in particular examples to computing devices designed for use in extreme and/or hazardous environments.

Computing devices for use in such environments are often required to operate in a wide range of conditions, including hot and cold temperature environments. At the same time, the devices need to be protected from dust and other environmental hazards. As a result, such devices may require complex air filtration systems for any air vents that are provided to assist with temperature management. Alternatively, devices can be environmentally sealed, but this can complicate temperature management. With sealed devices, access to the interior for maintenance purposes can also be more difficult.

The present invention seeks to alleviate some of these problems.

Accordingly, in a first aspect of the invention, there is provided a method of controlling a device, the device comprising a temperature sensor and a display having a light source, the method comprising: receiving temperature information from the temperature sensor; and controlling an amount of power supplied to the display light source in dependence on the received temperature information.

This allows the power supplied to the display light source (typically a backlight such as an LED backlight) to be controlled based on temperature in the device. Because the display light source also generates heat, controlling the supplied power also has the effect of controlling the heat output of the display light source. This approach thus allows the display to be utilised for heating and/or cooling of the device. Preferably the power control is performed to achieve a desired temperature in the device, more particularly in regions of the device (near or at components of the device) other than the display itself.

The temperature sensor is thus preferably not located at or within the display, but is preferably located remote from the display.

The method may comprise setting a level of power supplied to the display light source to a predetermined power level selected in dependence on the temperature measured by the temperature sensor, preferably wherein the predetermined power level is relative to a full power level corresponding to a maximum power that can be supplied to the display light source during normal operation. Alternatively, a power level may be calculated dynamically based on temperature. The power level may be controlled by supplying a power control signal (e.g. PWM coded or an analogue voltage level) to the display or a control component (e.g. a backlight inverter) associated with the display.

The method preferably comprises supplying a first amount of power to the display light source at a first measured temperature, and the controlling step comprises changing the first amount of power to a second amount of power different from the first amount in response to a change in the measured temperature to a second temperature. The first amount may correspond to a predetermined and/or user-configured normal display brightness. For example, within a particular temperature range, the power level may correspond to a user brightness setting, whilst outside that range, a different (e.g. higher or lower) power level may be applied.

The controlling step is preferably performed based on one or more thresholds.

Preferably, the method comprises selecting the amount of power from a plurality of power levels based on comparing the measured temperature to the one or more thresholds. The power levels may be predefined levels and/or may include a power level corresponding to a user brightness setting.

Preferably, the method comprises, in response to a temperature measured by the temperature sensor falling below a predetermined low-temperature threshold, increasing the power supplied to the display light source. The method may comprise, in response to the measured temperature being lower than a predetermined low temperature threshold, setting the amount of power supplied to the display light source to a predetermined high power level, preferably at least 80% of full power, more preferably at least 85% or at least 90% of full power or at least 95% of full power. The method preferably comprises, in response to the measured temperature being lower than a low temperature threshold, setting the power level to substantially full power.

The low-temperature threshold may be between -15°C and -35°C, more preferably between -22°C and -30°C, still more preferably between -24°C and -28°C, or approximately -26°C.

Preferably, the method comprises, in response to a temperature measured by the temperature sensor rising above a predetermined high-temperature threshold, reducing the power supplied to the display light source. The method may comprise, in response to the measured temperature being higher than a high temperature threshold, setting the power level to a predetermined low power level, preferably less than around 60% of full power, more preferably around 50% of full power.

The high-temperature threshold may be between +60°C and +80°C, more preferably between +65°C and +75°C, still more preferably between +68°C and +72°C, or approximately +70°C.

The method may comprise, in response to the measured temperature rising above a low-temperature threshold or falling to below a high-temperature threshold, setting the power level of the light source based on a user-configured brightness setting. The thresholds in this case (with temperature movement in the opposite direction to that described above) may be the same as the low and high-temperature thresholds above, but are preferably slightly different, preferably being higher or lower than the respective thresholds mentioned above by a difference of at least 1°C and preferably of around 2°C or more. The difference is preferably no more than 10°C, and is preferably around 5°C or less. The temperature threshold for rising temperature is preferably higher than the corresponding temperature threshold for falling temperature.

The device may comprise a heater, the method preferably including additionally controlling the heater based on the received temperature information. Alternatively or additionally, the device may comprise a fan, the method preferably including additionally controlling the fan based on the received temperature information. Controlling the heater and/or fan may include activating/deactivating the heater and/or fan and/or controlling an amount of power provided to the heater and/or fan. The heater and/or fan may be controlled in accordance with one or more activation/deactivation threshold temperatures, which may be different from power control temperature thresholds used to control the power supplied to the display light source.

Furthermore temperature thresholds for rising temperatures may in each case be different from those for falling temperatures as described above. Thus each of the display light source power level, fan and/or heater may be controlled in accordance with a respective set of preconfigured temperature thresholds.

In a further aspect of the invention, there is provided a method of powering up a computing device, the computing device comprising a display having a light source and a main processing module arranged to provide a display signal to the display, the method comprising: in response to activation of the computer device, initiating supply of power to the display light source at a first time; measuring a temperature in the device after the first time; in response to the temperature attaining a predetermined threshold at a second (later) time, activating the main processing unit; and providing a display signal to the display by the main processing unit after activation.

Thus, the main processing unit is inactive prior to the activating step, in particular during a period between the first and second times, while power is supplied to the display light source. No display signal is preferably supplied to, or output by, the display during this time. The time period between the first and second time typically depends on the measured temperature, the temperature threshold, and the rate of heating, but may be at least a second, in some cases at least 10 seconds. The time period may be at least 1 minute, or may even be 10 minutes or more (e.g. at particularly low temperatures).

The initiating step preferably comprises causing a first level of power to be supplied to the display light source, the method comprising, in response to the measured temperature attaining a second predetermined threshold (which may be the same as or different from the first threshold), reducing the level of power supplied to the display light source to a second (lower) level.

The method may further comprise controlling a heater and/or fan in response to the measured temperature. The method may comprise one or both of: switching on a heater at the first time in response to activation of the computing device; and switching off the heater at a third time in response to the temperature attaining a third predetermined threshold, preferably wherein the third predetermined threshold is different from (preferably higher than) the second predetermined threshold (and preferably also higher than the first threshold). Thus, the heater may remain on after the display light source reverts to a user-configured brightness setting. The heater is preferably a heater mat placed adjacent the display panel. The method may further comprise activating a fan at a fourth time, the fourth time preferably between the first and second times, in response to attaining a further predetermined threshold different from the first threshold (and optionally also different from the second and/or third thresholds). The fan is thus preferably activated some time after the display light source (and optionally the heater) is activated to provide heating of the device but before the main processing module is activated, i.e. after an initial amount of heating has occurred.

The measuring and activating and optionally the initiating steps are preferably performed by a control module of the device (for example in the form of a system monitor board).

The method may further comprise performing any or all steps of a method in accordance with the first aspect of the invention set out above.

In a further aspect, the invention provides a computer program or computer program product comprising software code adapted, when executed on a data processing apparatus, to perform any method as set out herein, including a method in accordance with the first and/or second aspects of the invention as set out above.

The invention further provides a control module for controlling a device, the device comprising a display having a light source, the control module comprising: means for receiving temperature information from a temperature sensor; and means for controlling an amount of power supplied to the display light source in dependence on the received temperature information. The temperature sensor may be part of the control module.

More generally, the invention also provides a control apparatus, device or module having means for performing any method as set out herein, including a method in accordance with the first and/or second aspects of the invention as set out above.

In a further aspect, the invention provides a computing device comprising: a display having a light source; a main processing module arranged to provide a display signal to the display; a control module; and a temperature sensor; wherein the control module is arranged to control an amount of power supplied to the display light source in dependence on a temperature measured by the temperature sensor. The control module is preferably arranged to perform a method as set out above in the first and/or second aspects of the invention and/or as described elsewhere herein.

The display preferably comprises a backlit display (e.g. an LCD), the light source comprising one or more display backlights, preferably LED backlight(s). The main processing module may comprise a single-board computer, SBC. The control module may comprise a system monitor board.

The computing device preferably comprises an enclosure having a front enclosure pad housing the display, and a rear enclosure part preferably formed substantially entirely of a heat-conducting material housing the main processing module and/or a power supply, wherein one or mare components of the main processing module and/or the power supply are mounted in heat-conducting contact with the rear enclosure part. For example, at least a CPU of the main processing module may be mounted in this way. Components may be in heat-conducting contact via an intermediary heat-conducting material, e.g. a surface plate or thermal pad fixed to the components and/or the enclosure.

The rear enclosure part preferably forms a heat sink covering substantially the whole rear surface of the computing device, the rear enclosure part preferably comprising a plurality of heat sink fins on an exterior surface.

In a further aspect of the invention, there is provided a hinge assembly, preferably for use in a computing device as set out above, comprising: a slide block arranged to be slidably mounted to at least one slide track, the slide track(s) arranged to be attached to a first surface; and a hinge bracket arranged to be attached to a second surface, the hinge bracket pivotably mounted on the slide block. This can provide a compact hinge arrangement, especially for use in a clamshell-type computer enclosure. The slide block is preferably slidable between a retracted position and an extended position, the hinge assembly comprising locking means, preferably comprising at least one locking pin, adapted to lock the slide block in place in the extended position.

The hinge bracket is preferably pivotable between open and closed positions, the hinge assembly further comprising locking means, preferably comprising at least one locking pin, adapted to lock the hinge bracket in place in the open position.

The hinge assembly is preferably arranged to allow simultaneous sliding and pivoting motion, preferably when the respective locking means are disengaged (i.e. in the unlocked positions).

The invention further provides a computing device comprising a hinge assembly as set out above, comprising first and second enclosure parts, wherein the slide track(s) are attached to a side wall of the first enclosure part, the hinge block being slidable in a direction substantially parallel to the side wall, and wherein the hinge bracket is attached to the second enclosure part.

The hinge assembly is preferably arranged to enable the second enclosure pad to be pulled away from and pivoted with respect to the first enclosure part. The computing device may be a computing device as previously set out.

The invention also provides a computer program and a computer program product for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein, and a computer readable medium having stored thereon a program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein.

The invention extends to methods and/or apparatus substantially as herein described with reference to the accompanying drawings.

Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa.

Furthermore, features implemented in hardware may generally be implemented in software, and vice versa. Any reference to software and hardware features herein should be construed accordingly.

Preferred features of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which:-Figures 1A and lB are front and rear views of a computing device in accordance with an embodiment of the invention; Figure 2 shows the computing device opened up; Figure 3 shows main components mounted in a rear enclosure of the computing device; Figure 4 is an exploded view of components of the front enclosure of the device; Figure 5 is a schematic diagram showing components of the computing device; Figures 6 and 7 illustrate heat management performed by a monitoring and control component in the device; Figure 8 illustrates operation of a sliding hinge assembly during opening of the device; Figure 9 illustrates the sliding hinge assembly; and Figure 10 is a schematic diagram illustrating control of the power supplied to display backlights.

Embodiments of the present invention provide an environmentally sealed integrated computing and display device with a clamshell-type enclosure.

The computing device is designed to be lightweight (liftable by a single person) and suitable for deployment in at least a Zone 2' hazardous area, for example for use within the oil and gas industry.

Figures 1-4 show different views of a particular embodiment.

A front view of the device 10 is shown in Fig. 1A, which shows the front part 12 of the enclosure including display area 14. Figure lB depicts a rear view, showing the rear part 16 of the enclosure. The rear enclosure 16 is formed of a single piece of machined aluminium alloy with integrated heat sink fins 18, and acts as a single large heat sink covering essentially the entire rear part of the device.

Figure 2 shows the device 10 in the open configuration. As seen here, the front enclosure 12 and rear enclosure 16 are joined by a hinge assembly 22.

The front enclosure houses a display assembly 24.

The rear enclosure 16 is shown in more detail in Figure 3 and houses various components of the computing device, including a power supply unit (PSU) 32, -10-a single-board computer (SBC) 34, and a slimline system monitor board (SSMB) 36.

PSU 32 comprises a circuit board with at least the main heat-generating components mounted in heat-conducting contact with (optionally partially or wholly embedded in) a metal block (e.g. aluminium) acting as a surface plate.

The surface plate is in direct contact with the rear enclosure to conduct heat from the PSU to the rear enclosure acting as a heat sink.

The SBC 34 is mounted with the main heat-generating components, in particular the processor(s), facing the rear enclosure, and are in contact with the rear enclosure via heat-conducting pads mounted on the inner surface of the rear enclosure, allowing heat to flow from the processor and other components to the rear enclosure. The rear enclosure 16 thus acts as a direct heat sink for the processor, PSU, and other hot components of the device.

The fin structures 18 on the exterior of the rear enclosure (Figure 1 B) assist in dissipating heat to the ambient air.

Additionally, a fan 38 provides for movement of air around the interior of the enclosure to enable even distribution of heat, which assists both in cooling and heating the enclosure as needed. A sealing strip 31 (e.g. silicon rubber) runs around the periphery of the rear enclosure to provide a seal when the rear enclosure is closed against the front enclosure.

In preferred embodiments, the device is environmentally sealed when in use and thus air flow vents are not provided. Nevertheless, the large heat sink formed by essentially the entire rear enclosure surface 30 provides a means for transporting heat from the air circulating in the enclosure to the exterior. If environmental sealing is not required, then the fan (or multiple fans) could additionally be arranged to direct air flow to air vents provided in the enclosure.

The front enclosure and display assembly are shown in exploded view in Figure 4. The display assembly includes an LCD display panel 44 and a

-U-

heater mat 45. The display panel 44 is mounted behind a touch screen glass sheet 42 secured to the frame of the front enclosure 12 by a glass clamp 43, which may be screwed or otherwise fixed to the front enclosure. An adhesive gasket 41 provides a seal between the glass and the front enclosure.

The heater mat 45 is bonded directly to the rear of the LCD display. The display panel is secured to a metal LCD chassis or bracket 46 which in turn is fixed to the front enclosure 12 (e.g. by screws or other suitable means).

The touch screen glass is preferably resistive or capacitive (other touch technologies could be used, or alternatively a glass without touch input could be used). The display uses LED backlighting.

The heating mat 45 provides heating for the entire enclosure, including the LCD panel and the other electronic components, when used in cold conditions. The fan is used to assist in even distribution of heat in such conditions. As described in more detail below, depending on conditions, the LED backlights of the LCD display panel may be used as a heat source when additional heating is required.

During hot conditions, the fan assists in transporting excess heat to the rear heat sink.

Figure 5 is a schematic diagram showing the main device components.

The power supply 32 provides power to the computing device (power supply is shown with dashed lines and control/data connections are shown with solid lines).

The monitor board (SSMB) 36 includes a temperature sensor 51, and controls operation of the heater 45, fan 38, display 44, and single-board computer (SBC) 34 based on temperature readings from the sensor 51. In addition to control signals, the monitor board also supplies power to the heater, fan and -12 -display. The SBC 34 is powered directly from the PSU, but could alternatively also receive its power via the monitor board.

The SBC 34 includes standard computer components such as one or more processor(s) 52, RAM 53, ROM/firmware 54, a display interface 55 and other I/O controllers/interfaces 56, and persistent storage 57 (e.g. in the form of flash memory or an SSD; alternatively, interfaces to integrated or removable magnetic or optical storage media could also be provided, such as a hard disk drive). The components communicate over one or more buses 58 as per conventional computer architectures.

The SBC 34 preferably uses low-power components. In one embodiment, the architecture is based on a dual-core Atom processor, though other processor architectures, such as those based on other Intel processors or ARM processors, could be used. As mentioned above, the CPU is positioned against a thermal pad fixed to the interior surface of the rear enclosure which acts as a heat sink. Other hot-running components may also be mounted in this way.

The monitor board 36 provides temperature monitoring and control of the other components in response to measured temperatures. Though in the described embodiment, the monitor board uses an integrated temperature sensor, the sensor may be located at any suitable location within the enclosure. Furthermore, multiple temperature sensors could be provided at different locations within the enclosure.

The heater mat 45 may include its own temperature sensor. This could be additionally used for control purposes by the monitor board. However, in the preferred embodiment it is used only to provide an emergency shutoff function in the event that the heating mat overheats (for example if the monitor board has failed to deactivate the heater for some reason). -13-

Temperature management The device controls the internal enclosure temperature using a variety of measures. As described above, the internal enclosure temperature is monitored using a temperature sensor located on the monitor board 36 which is positioned in the middle and towards the top of the enclosure (see Figure 3), which is likely to be the warmest part. The monitor board utilizes an embedded controller which operates independently of the SBC 34.

The two components on the rear of the enclosure that generate most heat (the PSU 32 and SBC 34) are located on opposite sides with the monitor board in the middle, so as to balance the generated heat profile by spreading the heat evenly across the whole of the rear heatsink which forms an integral part of the rear enclosure 16 (see Figures 1-3).

The fan 38 ensures that there are no hotspots within the enclosure and keeps the air moving across the rear heatsink surface 30. The fan also pulls heat away from the display assembly 24 and onto the rear enclosure, thus heatsinking the heat away to the outside environment. When the internal temperature reaches a predetermined threshold level, the display backlights are automatically dimmed to reduce the heat that they generate.

The heater mat 45 is fitted behind the display panel 44 (see Figure 4) and controlled by the monitor board 36. Additional heating mats or elements could be arranged at suitable locations and connected to the monitor board 36 if required.

The temperature of the heater mat 45 is monitored by the monitor board 36 using a thermistor temperature sensing device, accommodated within the heating mat. This thermistor is used to ensure that the mat does not overheat and present a temperature hazard. However, in preferred embodiments, the thermistor does not play an active pad in the control of the environment within the enclosure apart from disabling the mat should the mat temperature rise -14-above a pre-set level. This thermistor acts independently of the temperature sensor that is located on the monitor board 36.

The heater mat 45 fulfils two main functions: S * maintaining the LCD screen at a temperature such that the response time of the display is not severely compromised, and to thereby ensure adequate operation and display quality.

warming the air inside the sealed enclosure so that the SBC, and optionally other components, operate within specified operating temperature ranges.

In one example, the computing device is designed to operate across an external temperature range of -40°C to +60°C (though the exact operating range can of course be specified based on particular requirements and may differ from these values).

At the maximum specified external operating temperature of +60°C both cores of the SBC Atom processor attain temperatures of around +74°C whilst running at around 75% capacity. This generally means that there is no requirement to throttle back the processor speed to reduce the core temperatures (though this could be done; in some cases CPU throttling may be implemented within the SBC BIOS).

Embodiments of the present invention use the LCD display as an additional heat source for heating the device in cold conditions, whilst taking account of the display's heat output in warm conditions.

In particular, heating in a cold environment is accomplished by using the LCD heater mat together with the display's LED backlights. Using the LED backlights allows for a less powerful heater mat to be utilized. In the described embodiments, both heat sources combine to present about 65W of heating.

Of this, the mat provides around 50W whilst the LED backlights contribute around 15W. -15-

During excessive cold temperatures, at switch on, the SBC will not be enabled whilst the display backlights are switched on thus avoiding any picture being displayed. Normal operation is resumed once a predetermined internal enclosure temperature threshold has been reached. In the described embodiments this could take up to around 18 minutes (from an external ambient temperature of -40°C).

Figure 6 illustrates temperature control measures taken by the monitor board at switch-on and in response to rising temperatures after switch-on.

Application of power by the user (e.g. by switching on the device using a power switch or activating the device in some other way) activates the PSU 32 and monitor board 36 but not yet the main computer board, SBC 34. Instead, activation of the SBC is controlled by the controller on the monitor board 36 as part of a temperature-controlled startup sequence, based on temperature data received from the temperature sensor 51 (Figure 5).

In preferred embodiments, the device has a minimum operating temperature, in this example -40°C. Below that temperature, the device will not start up; instead, the monitor board will activate an alarm indication (e.g. an LED warning light in the front enclosure) indicating that conditions are too cold for operation.

If the temperature exceeds the minimum operating temperature (threshold Ri), then the monitor board follows the sequence shown in Figure 6.

First, the monitor board determines based on data from the temperature sensor that the temperature is sufficient for powering on the device but not yet sufficient for activating the SBC. The monitor board therefore switches on the heater mat (62). In addition, the monitor board switches on the display panel backlight (64). Since the SBC is off at this point, no display signal is provided to the display panel, and thus no display output is generated. However, the -16-heat output from the display panel backlight LEDs contributes to the heating of the device.

To maximise heat output, the LED backlight power is set to 100% during this warmup phase, though some other power level could be used. Display power is preferably controlled by way of pulse-width modulation (PWM) of a power control signal, and is hence indicated in Figures 6-7 as "%PWM", though output could be specified in other relative or absolute terms (e.g. as an absolute Watt value or in some other way).

Backlight control is illustrated in Figure 10. As shown, the power supply to the backlights is controlled by a backlight inverter receiving power along with a PWM control signal from the monitor board (see Figure 5). The backlight inverter provides a specified amount of power (ranging from 0% to 100% of a maximum power rating) to the backlights based on the power control signal.

Instead of a PWM control signal another form of digital or analogue control signal could be used (such as an analogue voltage level). The backlight inverter may be part of the display or may be separate.

The power supplied to the backlights determines the brightness of the backlights, and also, as a side effect, the heat output of the backlights.

Thus (referring back to Figure 6), during this initial part of the warmup phase, the enclosure is being heated by both the heater mat and by the heat output from the display panel backlights. Once the temperature reaches a fan activation threshold R2, in this example -30°C, the monitor board activates the fan (60), which begins to circulate heated air within the enclosure to provide for even distribution of heat. Delaying activation of the fan in this way allows the heater mat to warm up more quickly (storing heat within the silicon mat casing). If the fan were activated immediately (e.g. from -40°C), then heat would be transported away more quickly resulting in slower heat build-up during the start-up phase. -17-

At threshold R3 (in this example -25°C), the SBC is enabled (66) and starts operation. Threshold temperature R3 is chosen based on the operating range of the SBC. Shortly after, at threshold R4 (in this example -24°C) the display reverts to normal operation -i.e. the display panel starts to display the output signal generated by the SBC, and the backlight power is set to its normal level. That normal level could, for example, correspond to a stored user setting previously configured by the user, or some default value (which could be 100% or some other value). Thus, the backlight level may be different from the level during the warmup phase or it could remain at the same level.

At this point, the device has entered normal operation. In response to activation, the SBC carries out its normal boot process, typically involving loading an operating system and running any required applications. Output is displayed on the display and user input received via touch input from the display.

During this normal operation phase, the heater initially remains on until the temperature reaches a further threshold, R5, in this example -18°C. At this threshold, the SBC and other components are assumed to be able to operate adequately without external heating, and so the heating mat is switched off.

If at any time during operation the internal temperature exceeds a threshold R6, the monitor board initiates steps to reduce the temperature in the device.

In particular, in order to reduce the heat output of the display, the monitor board reduces the display's backlight power. In one embodiment, the backlight power is reduced to a set value, in this example 50% of total power, and remains at that level while the temperature exceeds the threshold.

Optionally, control of backlight power may be combined with other measures to reduce temperature, for example adjusting fan speed, or CPU throttling on the SBC (e.g. reducing the CPU clock speed to reduce the CPU power output). -18-

During both the warmup phase (R1-R5) and the cooling phase (above R6), a more fine-grained control of display backlight could be provided instead of using fixed backlight levels (in this example 100% during warmup, and 50% for cooling). For example, display backlight power could be increased or decreased in a set of incremental steps corresponding to respective thresholds, or a display backlight power level could be calculated dynamically based on the currently measured temperature (and optionally the current output of the heater mat).

Similarly, in this example the heater and fan are controlled to be either on or off. Alternative embodiments could provide for graduated control of the heater and/or the fan, e.g. in incremental steps or at dynamically calculated power output / speed settings.

Fig. 6 additionally shows a "heater mat enabled" bar (68), in this example from -40°C to 0°C. This relates to the failsafe operation of the heater mat as discussed above; if the temperature reaches the failsafe threshold (here 0°C), then the heater mat is disabled. However, during normal operation, such a situation should not occur, as the monitor board will have turned off the heater at threshold R5 (see bar 62 "Heater on").

Figure 7 illustrates temperature control measures taken by the monitor board in response to falling temperatures. The sequence is broadly similar to that of Figure 6, though individual thresholds may be different. In particular, thresholds at state transitions for falling temperatures are slightly lower or higher than corresponding thresholds for rising temperatures, to prevent rapid switching between on/off states or power levels when the temperature is fluctuating near a particular threshold.

As shown in Figure 7 and described above, at high temperatures (above threshold Fl), the display backlight is set at a reduced power level, in this example 50%. When the temperature falls below threshold Fl (in this example 65°C), backlight power is returned to its previous setting, which may be a user-configured setting or a default setting. Normal operation then resumes. -19-

If the temperature falls below threshold F2, in the example -20°C, the monitor board switches on the heater mat. Furthermore, if the temperature falls below threshold F3 (in the example -26°C), then the display backlight power level is increased, in this example to full power (i.e. 100%), assuming it was not already at that level. This increases the heat output from the display panel and thus contributes additional heating over and above that due to the heater mat.

As described above, though in this embodiment, the display backlight is set to full power, in other examples other values could be used, and/or the backlight level could be controlled incrementally or calculated dynamically.

At temperature threshold F4 (in the example -27°C), the fan is deactivated.

This prevents warmer air being moved away from the heat-generating components and allows those components to remain within their specified operating temperature ranges for longer.

Once the temperature falls below minimum operating temperature threshold F5 (in this example -40°C), the monitor board switches off the device (including SBC, display and heater), as reliable operation can no longer be ensured. The low temperature alarm is activated as described above to indicate to the user that the temperature is too low for reliable operation.

The monitor board preferably operates based on a control program running on the board's controller/processor. This may be stored in ROM/firmware on the monitor board. The control program carries out the control actions discussed above based on temperature data from the temperature sensor.

Figures 6-7 give particular examples of the various thresholds used in a particular embodiment (temperature scales are in °C). In practice, the specific threshold values may be set based on operating environment, component specifications, and other considerations. For example, the exact thresholds chosen for activating/deactivating the heater and setting the display backlight will depend on the heat output of the heater mat and of the display.

-20 -The thresholds may be fixed, or may alternatively be configurable, for example in order to adjust behaviour to specific operating environments. For example, the thresholds may be stored (e.g. as part of the control program) in the monitor board's firmware.

Mechanical design and hinge construction Referring back to Figure 2, as described above, the mechanical construction of the device enclosure comprises front and rear enclosure parts 12 and 16 that are held together by a hinge 22. The hinge facilitates the opening and closing of the enclosure and automatically locks the front in place when fully opened. This allows full access to the internal electronics for easy maintenance.

Both front and rear enclosure parts are machined from solid billets of aluminium alloy (in the present example the alloy is type 6082-T6, though other alloys, or pure aluminium, could be used). Other materials could in principle also be used; generally, materials that are low in weight and have good thermal conductivity are preferred, especially for the rear enclosure 16 which acts as a heat sink.

In one example, the device has overall dimensions of 476 x 427 x 90mm and weighs 12.2kg, though the same construction principles and heat management functionality can be applied to devices of any appropriate size.

The rear enclosure is secured to the front enclosure by way of eight retaining screws spaced evenly around the perimeter of the enclosure. Corresponding screw holes 26 are shown in Figure 2 (only some are labelled for clarity).

Once these retaining screws are removed, the device can be opened in a clamshell fashion using the sliding hinge 22, with the two halves of the enclosure pivoting about the hinge when pulled apart. -21 -

This is illustrated in Figure 8, which shows the device in half-open configuration. The hinge 22 is slidably mounted to the rear enclosure as indicated by the straight arrows. As the front part of the enclosure is pulled away from the rear, by grasping the right hand side, the hinge mechanism slides outwards from within the rear enclosure to allow the front to pull clear of the rear flange and sealing gasket.

During this movement the front enclosure 12 is allowed to pivot to allow the front to swing away from the rear, as indicated by the curved arrow. The sliding and pivoting motions can be accomplished in one fluid movement.

When the front is fully open, at around 90° to the rear (see Figure 2), the hinge will automatically lock in two places to stop the front from swinging shut once fully open, and to prevent the hinge from sliding back towards the rear of the rear enclosure.

The hinge assembly 22 is illustrated in more detail in Figure 9, in the open configuration of Figure 2.

The hinge assembly 22 comprises a hinge slide block 81, to which a hinge bracket 80 is pivotably mounted (within pivot bushes 83).

The hinge slide block 81 comprises hinge bearings 86 arranged to run along hinge bearing tracks 84. Additionally, hinge guide rails 85 are provided which extend into corresponding recesses 89 in the slide block 81. The hinge guide rails include apertures (not shown) for receiving spring-loaded locking pins 88 in order to lock the hinge assembly in place (preventing sliding motion of the hinge assembly) after being pulled out of the rear enclosure. An additional spring-loaded locking pin 87 is provided at one end of the hinge bracket 80 which engages a corresponding aperture (not shown) in the slide block 81 to lock the hinge bracket in the open position (and prevent further pivoting of the hinge bracket with respect to the slide block). The locking pins 87 and 88 are shown in their locked positions in Figure 9.

-22 -The hinge bracket 80 is fixed to the front enclosure, e.g. using screws. The guide rails 85 and bearing tracks 84 are screwed or otherwise mounted to a side wall of the rear enclosure (see Figure 2).

S In a preferred embodiment, the main hinge slide block is machined from solid aluminium and the hinge bracket is manufactured from stainless steel, though other materials could be used.

In order to close the enclosure, with the application of gentle pressure on the front enclosure in a closing direction, spring-loaded locking pin 87 can be pulled up and out of its locked position and held there whilst the front enclosure is folded towards the rear enclosure. Then, whilst still applying slight pressure on the front in a direction towards the rear of the enclosure the remaining two spring-loaded locking pins 88 can be pulled up, allowing the hinge assembly to slide fully into the rear enclosure. The eight enclosure retaining screws can then be fastened up to ensure that the enclosure is securely sealed against the ingress of moisture and dust.

It will be understood that the present invention has been described above purely by way of example, and modification of detail can be made within the scope of the invention.

Claims

-23 -CLAIMS1. A method of controlling a device, the device comprising a temperature sensor and a display having a light source, the method comprising: receiving temperature information from the temperature sensor; and controlling an amount of power supplied to the display light source in dependence on the received temperature information.
2. A method according to claim 1, comprising setting a level of power supplied to the display light source to a predetermined power level selected in dependence on the temperature measured by the temperature sensor, preferably wherein the predetermined power level is relative to a full power level corresponding to a maximum power that can be supplied to the display light source during normal operation.
3. A method according to claim 1 or 2, comprising supplying a first amount of power to the display light source at a first measured temperature, and wherein the controlling step comprises changing the first amount of power to a second amount of power different from the first amount in response to a change in the measured temperature to a second temperature.
4. A method according to claim 3, wherein the first amount corresponds to a predetermined and/or user-configured normal display brightness.
5. A method according to any of the preceding claims, wherein the controlling step is performed based on one or more thresholds.
6. A method according to claim 5, comprising selecting the amount of power from a plurality of power levels based on comparing the measured temperature to the one or more thresholds.
7. A method according to any of the preceding claims, comprising, in response to a temperature measured by the temperature sensor falling below -24 -a predetermined low-temperature threshold, increasing the power supplied to the display light source.
8. A method according to any of the preceding claims, comprising, in response to the measured temperature being lower than a predetermined low temperature threshold, setting the amount of power supplied to the display light source to a predetermined high power level, preferably at least 80% of full power, more preferably at least 90% of full power or at least 95% of full power.
9. A method according to any of the preceding claims, comprising, in response to the measured temperature being lower than a low temperature threshold, setting the power level to substantially full power.
10. A method according to any of the preceding claims, comprising, in response to a temperature measured by the temperature sensor rising above a predetermined high-temperature threshold, reducing the power supplied to the display light source.
11. A method according to any of the preceding claims, comprising, in response to the measured temperature being higher than a high temperature threshold, setting the power level to a predetermined low power level, preferably less than around 60% of full power, more preferably around 50% of full power.
12. A method according to any of the preceding claims, comprising, in response to the measured temperature rising above a low-temperature threshold or falling to below a high-temperature threshold, setting the power level of the light source based on a user-configured brightness setting.
13. A method according to any of the preceding claims, wherein the device further comprises a heater, the method including additionally controlling the heater based on the received temperature information.

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14. A method according to any of the preceding claims, wherein the device further comprises a fan, the method including additionally controlling the fan based on the received temperature information.
15. A method of powering up a computing device, the computing device comprising a display having a light source and a main processing module arranged to provide a display signal to the display, the method comprising: in response to activation of the computer device, initiating supply of power to the display light source at a first time; measuring a temperature in the device after the first time; in response to the temperature attaining a predetermined threshold at a second time, activating the main processing unit; and providing a display signal to the display by the main processing unit after activation.
16. A method according to claim 15, wherein the initiating step comprises causing a first level of power to be supplied to the display light source, the method comprising, in response to the measured temperature attaining a second predetermined threshold, reducing the level of power supplied to the display light source to a second level.
17. A method according to claim 15 or 16, further comprising controlling a heater and/or fan in response to the measured temperature.
18. A method according to any of claims 15 to 17, comprising one or both of: switching on a heater at the first time in response to activation of the computing device; and switching off the heater at a third time in response to the temperature attaining a third predetermined threshold, preferably wherein the third predetermined threshold is different from the second predetermined threshold.
19. A method according to any of claims 15 to 18, comprising activating a fan at a fourth time, the fourth time preferably between the first and second -26 -times, in response to attaining a further predetermined threshold different from the first threshold.
20. A method according to any of claims 15 to 19, further comprising performing a method according to any of claims ito 14.
21. A computer program or computer program product comprising software code adapted, when executed on a data processing apparatus, to perform a method as claimed in any of the preceding claims.
22. A control module having means for performing a method as claimed in any of claims ito 20.
23. A computing device comprising: a display having a light source; a main processing module arranged to provide a display signal to the display; a control module; and a temperature sensor; wherein the control module is arranged to control an amount of power supplied to the display light source in dependence on a temperature measured by the temperature sensor.
24. A computing device according to claim 23, wherein the control module is arranged to perform a method as set out in any of claims 1 to 20.
25. A computing device according to claim 23 or 24, wherein the display comprises a backlit LCD, the light source comprising one or more display backlights.
26. A computing device according to any of claims 23 to 25, wherein the main processing module comprises a single-board computer, SBC.

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27 - 27. A computing device according to any of claims 23 to 26, wherein the computing device comprises an enclosure having a front enclosure part housing the display, and a rear enclosure part formed of a heat-conducting material housing the main processing module and/or a power supply, wherein one or more components of the main processing module and/or the power supply are mounted in heat-conducting contact with the rear enclosure part.
28. A computing device according to claim 27, wherein the rear enclosure part forms a heat sink covering substantially the whole rear surface of the computing device, the rear enclosure part preferably comprising a plurality of heat sink fins.
29. A hinge assembly, preferably for use in a computing device as set out in any of claims 23 to 28, comprising: a slide block arranged to be slidably mounted to at least one slide track, the slide track(s) arranged to be attached to a first surface; and a hinge bracket arranged to be attached to a second surface, the hinge bracket pivotably mounted on the slide block.
30. A hinge assembly according to claim 29, wherein the slide block is slidable between a retracted position and an extended position, the hinge assembly comprising locking means, preferably comprising at least one locking pin, adapted to lock the slide block in place in the extended position.
31. A hinge assembly according to claim 29 or 30, wherein the hinge bracket is pivotable between open and closed positions, the hinge assembly further comprising locking means, preferably comprising at least one locking pin, adapted to lock the hinge bracket in place in the open position.
32. A hinge assembly according to any of claims 29 to 31, wherein the hinge assembly is arranged to allow simultaneous sliding and pivoting motion.
33. A computing device comprising a hinge assembly as claimed in any of claims 29 to 32, comprising first and second enclosure parts, wherein the slide -28 -track(s) are attached to a side wall of the first enclosure part, the hinge block being slidable in a direction substantially parallel to the side wall, and wherein the hinge bracket is attached to the second enclosure part.
34. A computing device according to claim 33, wherein the hinge assembly is arranged to enable the second enclosure part to be pulled away from and pivoted with respect to the first enclosure part.
35. A computing device according to claim 33 or 34, wherein the computing device is a computing device as set out in any of claims 23 to 28.
36. A method of controlling a device substantially as described herein with reference to the accompanying drawings.
37. A computing device or control module for a computing device substantially as described herein with reference to, and/or as illustrated in, the accompanying drawings.
38. A hinge assembly substantially as described herein with reference to, and/or as illustrated in, the accompanying drawings.