Emergency lighting apparatus, associated method and computer program instructions

TECHNOLOGICAL FIELD

Embodiments of the present invention relate to an emergency lighting apparatus. In particular, they relate to heating at least one battery in an emergency lighting apparatus in order to maintain the temperature of the battery within its operating temperature range.

BACKGROUND

An emergency lighting apparatus is configured to provide light when a mains power outage occurs. Emergency lighting apparatuses may, for example, be located inside commercial or residential buildings. Each commercial lighting apparatus has a battery which is charged by mains power. In the event of a mains power outage, the emergency lighting apparatus switches on automatically and draws power from the battery.

BRIEF SUMMARY

According to various, but not necessarily all, embodiments of the invention there is provided an emergency lighting apparatus for providing light during a mains power outage, the emergency lighting apparatus comprising: at least one battery for electrical connection to at least one light source, in order to provide power to the at least one light source; temperature sensing means for sensing the temperature of the at least one battery; heating means arranged to heat the at least one battery; and control means configured to control the heating means to heat the at least one battery based, at least in part, on at least one input from the temperature sensing means.

The control means may be configured to respond to reception of at least one input from the temperature sensing means indicating that the temperature of the battery is below a threshold temperature by causing the heating means to heat the battery. The control means may be configured to monitor the temperature of the battery while the heating means is heating the battery. The control means may be configured to control the heating means based, at least in part, on inputs received from the temperature sensing means while the heating means is heating the battery.

The control means may be configured to cause a pulse-width modulated signal to be provided to the heating means in order to control the rate at which heat is generated by the heating means.

The control means may be configured, in response to reception of the input from the temperature sensing means indicating that the temperature of the battery is below the threshold temperature, to cause a pulse-width modulated signal to be provided to the heating means. The control means may be configured to adjust the duty cycle of the pulse-width modulated signal in response to at least one further input from the temperature sensing means.

The control means may be configured, if the further input indicates no increase in the temperature of the battery or indicates that the rate of increase is below a threshold rate of increase, to increase the duty cycle of the pulse-width modulated signal.

The control means may be configured to gradually increase the duty cycle of the pulse- width modulated signal when inputs are received from the temperature sensing means indicating that the temperature of the battery is not increasing or is increasing below the threshold rate of increase.

The control means may be configured to gradually reduce the duty cycle of the pulse- width modulated signal when inputs are received from the temperature sensing means indicating that the temperature of the battery is increasing and approaching a target temperature.

The control means may be configured to control the heating means to cease generating heat when at least one input is received from the temperature sensing means indicating that the temperature of the battery has reached the target temperature. The emergency lighting apparatus may further comprise switching means, different from the control means, configured to receive inputs from the temperature sensing means and configured to switch off power to the heating means in response to reception of at least one input from the temperature sensing means indicating that the temperature of the battery exceeds a particular temperature.

The switching means may be configured to reinstate power to the heating means in response to reception of at least one input from the temperature sensing means indicating that the temperature of the battery is below the particular temperature.

The heating means may be arranged to be powered using power sourced from a mains power supply. The heating means may comprise at least one electrical component for producing heat. The electrical heating component(s) may comprise at least one resistor configured to generate heat via resistive heating.

The temperature sensing means may comprise at least one temperature sensor. The heating means may comprise at least one electrical component. The temperature sensor(s) and the electrical component(s) may be mounted to a printed circuit board.

The electrical component(s) and the temperature sensor(s) may be mounted on the same side of the printed circuit board. Alternatively, the electrical component(s) and the temperature sensor(s) may be mounted on different sides of the printed circuit board.

The printed circuit board may have a first face facing towards the battery and a second face facing away from the battery. The temperature sensor(s) may be mounted on the first face and the electrical component(s) may be mounted on the second face.

The printed circuit board may comprise at least one thermal via for conducting heat generated by the electrical component(s) towards the battery. The printed circuit board may include a thermally conductive material positioned between adjacent electrical components.

The emergency lighting apparatus may further comprise a housing for housing the battery. The housing may comprise a first end cap and a second end cap. The first end cap may comprise a first recess for receiving a first end of the battery and a first elongate slot for receiving a first end of the printed circuit board. The second end cap may comprise a second recess for receiving a second end of the battery and a second elongate slot for receiving a second end of the printed circuit board. The housing may further comprise a cover arranged to extend from the first end cap to the second end cap.

According to various, but not necessarily all, embodiments of the invention there is provided a method of heating at least one battery in an emergency lighting apparatus, comprising: receiving at least one input from temperature sensing means; and controlling heating means to heat the battery based, at least in part, on the input from the temperature sensing means

According to various, but not necessarily all, embodiments of the invention there is provided computer program instructions that, when executed by control means of the emergency lighting apparatus, cause the control means to perform the method.

According to various, but not necessarily all, embodiments of the invention there is provided an emergency lighting apparatus for providing light during a mains power outage, the emergency lighting apparatus comprising: at least one light source; at least one battery for electrical connection to at least one light source, in order to provide power to the at least one light source; temperature sensing means for sensing the temperature of the at least one battery; heating means arranged to heat the at least one battery; and control means configured to: respond to reception of at least one input from the temperature sensing means, indicating that the temperature of the at least one battery is below the threshold temperature, by causing a pulse-width modulated signal to be provided to the heating means in order to cause the heating means to heat the at least one battery; respond to reception of inputs from the temperature sensing means, indicating that the temperature of the at least one battery is not increasing or is increasing at a rate below a threshold rate of increase, by gradually increasing the duty cycle of the pulse-width modulated signal to increase the rate at which heat is generated by the heating means; and respond to reception of at least one input from the temperature sensing means, indicating that the temperature of the at least one battery is increasing towards a target temperature by gradually reducing the duty cycle of the pulse-width modulated signal to reduce the rate at which heat is generated by the heating means; and respond to at least one input from the temperature sensing means, indicating that the temperature of the at least one battery is at the target temperature by causing provision of the pulse-width modulated signal to the heating means to cease in order to cause the heating means to cease providing heat to the at least one battery.

According to various, but not necessarily all, embodiments of the invention there is provided a housing for housing a battery and a printed circuit board in an emergency lighting apparatus, the housing comprising: a first end cap comprising a first recess for receiving a first end of the at least one battery and a second recess for receiving a first end of a printed circuit board; a second end cap comprising a third recess for receiving a second end of the at least one battery and a fourth recess for receiving a second end of the printed circuit board; and a cover arranged to extend from the first end cap to the second end cap.

According to various, but not necessarily all, embodiments of the invention there is provided a battery apparatus for an emergency lighting apparatus that is for providing light during a mains power outage, the battery apparatus comprising: at least one battery for electrical connection to at least one light source, in order to provide power to the at least one light source; temperature sensing means for sensing the temperature of the at least one battery; heating means arranged to heat the at least one battery; and control means configured to control the heating means to heat the at least one battery based, at least in part, on at least one input from the temperature sensing means.

According to various, but not necessarily all, embodiments of the invention there is provided examples as claimed in the appended claims.

BRIEF DESCRIPTION

For a better understanding of various examples that are useful for understanding the detailed description, reference will now be made by way of example only to the accompanying drawings in which:

fig. 1 illustrates a schematic of an emergency lighting apparatus; fig. 2A illustrates a first example of a printed circuit board comprising temperature sensing means and heating means;

fig. 2B illustrates a second example of a printed circuit board comprising temperature sensing means and heating means;

fig. 2C illustrates a third example of a printed circuit board comprising temperature sensing means and heating means;

figs. 3A to 3F illustrate a battery and a printed circuit board being housed by a housing; fig. 4 illustrates heating means providing heat to a battery; and

fig. 5 illustrates a flow chart of a method.

DETAILED DESCRIPTION

Typically, batteries function best at room temperature. An operating temperature range may be provided for a battery within which the battery’s performance is considered to be acceptable. If the temperature of the battery drops below the minimum temperature stated in the operating temperature range, both the capacity and the lifespan of the battery are likely to be reduced.

Embodiments of the present invention relate to an emergency lighting apparatus 10 comprising at least one battery 24. In particular, they relate to heating the battery/batteries 24 in the apparatus 10 in order to maintain the temperature of the battery within its operating temperature range.

Fig. 1 illustrates a schematic of an emergency lighting apparatus 10 for providing light during a mains power outage. The emergency lighting apparatus 10 comprises a battery apparatus 1 1 and at least one (electrical) light source 26. The battery apparatus 1 1 comprises a controller/control means 12, temperature sensing means 20, heating means 22 and at least one battery 24. Each of the illustrated elements 12, 20, 22, 24, 26 is operationally coupled and any number or combination of intervening elements (such as intervening circuitry) can exist (including no intervening elements).

The battery apparatus 11 may, for example, be retrofitted to an existing emergency lighting apparatus 10. The temperature sensing means 20 may, for example, comprise or consist of one or more (electrical) temperature sensors. The temperature sensing means 20 is arranged to sense the temperature of the battery 24. The temperature sensing means 20 may, for example, be positioned close to the battery 24. The control means 12 is configured to receive inputs from the temperature sensing means 20 indicating a (current) temperature of the battery 24.

The heating means 20 is arranged to generate heat to heat the battery/batteries 24. The heating means 20 may, for example, comprise or consist of one or more electrical components. The one or more electrical components may be configured to generate heat via resistive heating. In some embodiments, the one or more electrical components may include one or more resistors and/or one or more light emitting diodes, for example, that are configured to generate heat via resistive heating. The control means 12 is configured to cause the heating means 22 to generate heat. The control means 12 may provide a control signal, such as a pulse-width modulated signal, that causes the heating means 22 to generate heat. The control signal that is provided by the control means 12 is based, at least in part, on at least one input from the temperature sensing means 20.

In some embodiments, the control means 12 provides the control signal directly to the heating means 22 to cause it to generate heat. In other embodiments, the control means 12 provides the control signal to (intermediate) circuitry which responds to that control signal by providing a further control signal (such as a pulse-width modulated signal) to the heating means 22, which causes it to generate heat.

A single battery 24 or multiple batteries 24 may be provided that is/are electrically connected to the light sources(s) 26. For ease of explanation, a single battery 24 is referred to from here onwards. The battery 24 may be any type of battery, including a lithium-ion battery, a nickel-cadmium (Ni-Cad) battery or a nickel-metal hydride (Ni MH) battery.

The apparatus 10 may comprise circuitry that causes the battery 24 to provide (electrical) power to the light source(s) 26 in the event of a mains power outage, which in turns causes the light source(s) to begin emitting light. The light source(s) 26 may be any type of electrical light source(s), including, for example, one or more light emitting diodes and/or one or more halogen light sources and/or one or more fluorescent light sources.

The control means 13, the temperature sensing means 20 and the heating means 22 are powered using power that is sourced from a mains power supply. The battery 24 is charged using power that is sourced from the mains power supply. The mains supply may be down-converted from a voltage in the range 110v-240v to a voltage in the range 2v-12v in order to power the control means 13, the temperature sensing means 20 and the heating means 22 and to charge the battery 24.

The control means 12 may, for example, comprise at least one processor 13 and memory 14. The control means 12 may be implemented in hardware alone, have certain aspects in software including firmware alone or can be a combination of hardware and software (including firmware).

As illustrated in fig. 1 the control means 12 may be implemented using instructions that enable hardware functionality, for example, by using executable instructions of a computer program 16 in a general-purpose or special-purpose processor 13 that may be stored on a computer readable storage medium (disk, memory etc.) to be executed by such a processor 13.

The processor 13 is configured to read from and write to the memory 14. The processor 13 may also comprise an output interface via which data and/or commands are output by the processor 13 and an input interface via which data and/or commands are input to the processor 13.

The memory 14 stores a computer program 16 comprising computer program instructions (computer program code) that controls the operation of the apparatus 10 when loaded into the processor 13. The computer program instructions, of the computer program 16, provide the logic and routines that enables the control means 12/processor 13/apparatus 10 to perform the method illustrated in fig. 5. The processor 13 by reading the memory 14 is able to load and execute the computer program 16.

As illustrated in fig. 1 , the computer program 16 may arrive at the apparatus 10 via any suitable delivery mechanism 8. The delivery mechanism 8 may be, for example, a non- transitory computer-readable storage medium, a computer program product, a memory device, a record medium such as a Compact Disc Read-Only Memory (CD- ROM) or Digital Versatile Disc (DVD), or a different article of manufacture that tangibly embodies the computer program 16. The delivery mechanism 8 may be a signal configured to reliably transfer the computer program 16. The apparatus 10 may propagate or transmit the computer program 16 as a computer data signal.

Although the memory 14 is illustrated as a single component/circuitry it may be implemented as one or more separate components/circuitry some or all of which may be integrated/removable and/or may provide permanent/semi-permanent/ dynamic/cached storage.

Although the processor 12 is illustrated as a single component/circuitry it may be implemented as one or more separate components/circuitry some or all of which may be integrated/removable. The processor 12 may be a single core or multi-core processor.

Fig. 2A illustrates a first example of a printed circuit board 21 comprising temperature sensing means 20 and heating means 22. In this example, the temperature sensing means 20 comprises a plurality of discrete, surface mounted electrical temperature sensors that are positioned along a central channel of the printed circuit board 21. The heating means 22 comprises two channels of discrete, surface mounted electrical components that generate heat via resistive heating. The channels of electrical heating components are positioned either side of the channel of temperature sensors. In the example illustrated in fig. 2A, both the temperature sensing means 20 and the heating means 22 are mounted to the same side of the printed circuit board 21. The printed circuit board 21 in the example illustrated in fig. 2A may, for example, be an aluminium printed circuit board that conducts heat between the electrical components of the heating means 22 reasonably well, providing a reasonably uniform distribution of heat along the two channels of electrical heating components.

Fig. 2B illustrates a second example of a printed circuit board 21 comprising temperature sensing means 20 and heating means 22. The second example illustrated in fig. 2B differs from the first example illustrated in fig. 2A in that a thermally conductive material 23, such as copper, is provided on the printed circuit board 21 between adjacent electrical components to enable heat to be conducted along the channels on the printed circuit board 21 in which the electrical components of the heating means 22 are positioned. Advantageously, this may enable heat to be radiated more evenly, in particular if the printed circuit board 21 is made from a material that is a poor conductor of heat, such as fibreglass.

Fig. 2C illustrates a third example of a printed circuit board 21 comprising temperature sensing means 20 and heating means 22. In the third example, one or more temperature sensors of the temperature sensing means 20 are mounted to a different surface/side of the printed circuit board 20 from one or more electrical components of the heating means 22. The two sides/surfaces are separated by the thickness of the printed circuit board 21. In this example, the printed circuit board 21 comprises a number of thermal vias/holes 25 that enable the heat generated by the heating means to be radiated through the thickness of the printed circuit board 21.

In the fig. 2A and 2B examples, both the temperature sensor(s) of the temperature sensing means 20 and the electrical component(s) of the heating means 22 are mounted on a first face of the printed circuit board 21 that faces towards the battery 24. In the fig. 2C example, the temperature sensor(s) of the temperature sensing means 20 is/are mounted on a first face of the printed circuit board 21 that faces towards the battery 24 and the electrical component(s) of the heating means 22 is/are mounted on a second face of the printed circuit board 21 that faces away from the battery 24. The thermal vias 25 enable heat that is generated by the heating means 22 to be conducted through the printed circuit board 21 and towards the battery 24.

In each of the examples illustrated in figs. 2A, 2B and 2C, the temperature sensing means 20 may be thermally isolated from the heating means 22.

As mentioned above, the electrical components of the heating means 22 may comprise a plurality of resistors. Resistors are typically rated at 0.125w-0.25w of power. If there were a requirement to provide 6w of power in total from resistors that are rated at 0.125w, 48 resistors would be required. It will be appreciated by those skilled in the art, however, that any quantity or combination of electrical heating components could be used. Figs. 3A to 3F illustrate the battery 24 and the printed circuit board 21 being housed by a housing. The housing comprises a first end cap 30, a second end cap 40 and a cover 50 arranged to extend from the first end cap 30 to the second end cap 40.

The first end cap 30 comprises a first recess 32 for receiving a first end 24a of the battery 24 and a second recess/slot 36 for receiving a first end 21a of the printed circuit board 21. The second recess 36 is different from the first recess 32 and is positioned beneath the first recess 32.

The first recess 32 is shaped to receive a first end 24A of a cylindrical battery 24, but this need not be the case in every example. The first recess 32 also includes one or more apertures 34 through which electrical connections to the battery 24 may be positioned. The second recess 36 is shaped as an elongate slot in the illustrated example, but this need not be the case in every example.

The second end cap 40 has the same shape and configuration as the first end cap 30. In this regard, the second end cap 40 comprises a third recess 42 which is equivalent to the first recess 32 in the first end cap 30, and a fourth recess 46 which is equivalent to the second recess 36 in the first end cap 30. The second end cap also includes a plurality of apertures 44 to enable electrical connections to the second end 24b of the battery 24 to be made through the second end cap 40.

In the illustrated example, each of the end caps 30, 40 includes a notch that enables the end caps 30, 40 to be fixed to an internal surface of an exterior housing of the emergency lighting apparatus 10. The notch in the first end cap 30 cannot be seen in the figures. It has the same shape as the notch 48 that can be seen in the second end cap 40 in the figures.

Figs. 3A and 3B illustrate a first end 21a of the circuit board 21 being inserted into the second recess 36 in the first end cap 30, and illustrates the second end 21 b of the printed circuit board 20 being inserted into the fourth recess 46 of the second end cap 40. Fig. 3C illustrates a first end 24a of the battery 24 being inserted into the first recess 32 of the first end cap 30, and illustrates the second end 24b of the battery 24 being inserted into the third recess 42 of the second end cap 40.

Fig. 3D illustrates the cover 50 being fixed to the first and second end caps 30, 40. In this embodiment, the cover 50 achieves a friction fit with the first and second end caps 30, 40 which holds it in place.

Figs. 3E and 3F illustrate a perspective view and a cross-sectional view of the housing while it is housing the battery 24 and the printed circuit board 21.

In the example illustrated in figs. 3A to 3F, the printed circuit board 21 that is shown is that illustrated in fig. 2A. In other examples, a different printed circuit board 21 may be used, such as those illustrated in figs. 2B and 2C. In each of these examples, the temperature sensing means 20 is mounted to the printed circuit board 21 such that it is adjacent to and facing the battery 24. This enables a particularly accurate temperature measurement of the temperature of the battery 24 to be obtained. The heating means 22 may also be arranged on the printed circuit board 21 to face the battery 24 (such as in the examples of the printed circuit board 21 illustrated in figs. 2A and 2B), but in other examples the heating means 22 may be positioned on the opposite side of the printed circuit board 21 (such as the example of the printed circuit board 21 illustrated in fig. 2C).

Fig. 4 illustrates a cross-section of the cover 50, battery 24 and the printed circuit board 21 , while the heating means 22 is generating heat to heat the battery 24. The cover 50 around the battery 24 provides thermal insulation to contain heat generated by the heating means 22. The arrows labelled with the reference numeral 60 depict the generated heat being directed towards the battery 24. In fig. 4, the temperature sensing means 20 is touching the battery 24. In other examples, the temperature sensing means 20 may be adjacent to, but not quite touching, the battery 24.

Fig. 5 illustrates a flowchart of a method that is performed by the control means 12 in order to cause the heating means 22 to generate heat to heat the battery 24. The control means 12 is responsive to inputs received from the temperature sensing means 20. If the temperature sensing means 20 includes more than one temperature sensor, the control means 12 may be configured to determine a single representative temperature value from the inputs that are received from multiple temperature sensors. It might, for example, determine the average temperature value from the inputs provided by the temperature sensors.

The control means 12 is configured to continuously monitor the temperature of the battery 24 via the inputs that it receives from the temperature sensing means 20. This temperature monitoring is ongoing, irrespective of whether the heating means 22 is currently generating heat to heat the battery 24.

In block 501 in fig. 5, the heating means 22 is not currently generating heat to heat the battery 24. The control means 12 receives at least one input from the temperature sensing means 20 that indicates that the temperature of the battery 24 has fallen below a lower threshold of an operating range. By way of example, the operating range for a Ni-Cad battery might be 5°C to 55°C. The operating temperature range for a Ni-MH battery might be 15°C to 40°C.

In block 502 of fig. 5 the control means 12 responds to the input(s) received in block 501 by providing a control signal that causes the heating means 22 to generate heat in order to heat the battery 24.

In block 503 in fig. 5, the control means 12 continues to monitor the temperature of the battery 24 by receiving inputs from the temperature sensing means 22 while the heating means 22 is heating the battery 24.

In block 504 in fig. 5 the control means 12 receives at least one input from the temperature sensing means 20 indicating that the temperature of the battery 24 is not increasing, or indicating that the rate of temperature increase of the battery 24 is below a threshold rate (i.e. the temperature of the battery 24 is increasing slowly). In block 505 in fig. 5, the control means 12 controls the heating means 22 to increase the rate at which heat is generated by the heating means 22. As mentioned above, in some embodiments, the control means 12 is configured to cause a pulse-width modulated signal to be provided to the heating means 22 in order to control the rate at which heat is generated by the heating means 22. The control means 12 may, for example, cause a pulse-width modulated signal with a first duty cycle to be provided to the heating means 22 in block 502 and then adjust/increase the duty cycle to a second duty cycle in block 505 in order to increase the rate at which heat is generated by the heating means 22.

The control means 12 may gradually increase the duty cycle of the pulse-width modulated signal when inputs are received from the temperature sensing means 20 indicating that the temperature of the battery 20 is not increasing, or is increasing at a rate below the threshold rate of increase.

In block 506 in fig. 5, the control means 12 receives at least one input from the temperature sensing means 20 indicating that the temperature of the battery 24 is within the operating range and approaching a target temperature. For example, the input(s) from the temperature sensing means 20 may indicate that the battery 24 is at its target temperature (e.g. 20°C) or is within a range (such as 18°C to 20°C) which is below the target temperature and within the operating range of the battery 24. In block 507 in fig. 5, the control means 12 responds to the input(s) received in block 506 by controlling the heating means 22 to reduce the rate at which the heating means 22 generates heat.

In block 508 in fig. 5, the control means 12 receives one or more inputs from the temperature sensing means 20 indicating that the temperature of the battery 24 has reached the target temperature. In block 509 in fig. 5, the control means 12 responds to the input(s) received in block 508 by controlling the heating means 22 to cease generating heat. For example, the control means 12 may cause provision of the pulse- width modulated signal to the heating means 22 to cease.

The method in fig. 5 then reverts from block 509 to 501 , and the method recommences if and when the control means 12 receives one or more inputs from a temperature sensing means 20 indicating that the temperature of the battery 24 has fallen below the lower threshold of the operating range of the battery 24.

In some embodiments of the invention, the battery apparatus 11 may comprise switching means, that is different from the control means 12, which is configured to receive inputs from the temperature sensing means 20. The switching means may be configured to switch off power to the heating means 22 in response to reception of at least one input from the temperature sensing means 20 indicating that the temperature of the battery 24 exceeds a particular temperature. The particular temperature may, for example, be a value which corresponds with the upper threshold of the operating range of the battery 24 or a value that exceeds the upper threshold of the operating temperature range of the battery 24. This is a fail-safe mechanism for ensuring that the battery 24 is not inadvertently heated by the heating means 22.

The switching means may be configured to reinstate power to the heating means 22 in response to reception of at least one input from the temperature sensing means 20 indicating that the temperature of the battery 24 is below the particular temperature.

References to ‘computer-readable storage medium’, ‘computer program product’, ‘tangibly embodied computer program’ etc. or a‘controller’, ‘computer’, ‘processor’ etc. should be understood to encompass not only computers having different architectures such as single/multi-processor architectures and sequential (Von Neumann)/parallel architectures but also specialized circuits such as field- programmable gate arrays (FPGA), application specific circuits (ASIC), signal processing devices and other processing circuitry. References to computer program, instructions, code etc. should be understood to encompass software for a programmable processor or firmware such as, for example, the programmable content of a hardware device whether instructions for a processor, or configuration settings for a fixed-function device, gate array or programmable logic device etc.

The blocks illustrated in fig. 5 may represent steps in a method and/or sections of code in the computer program 16. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some blocks to be omitted.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed. For example, the control means 12 might be provided by discrete electronics rather than a processor 12 and memory 14 storing a computer program 16. The control means 12 might cause a varying direct current (DC) voltage control signal to be provided to the heating means 22 rather than a pulse width modulated control signal.

In an alternative implementation to those illustrated in figures 2A to 4, the battery 24 might be mounted onto the printed circuit board 21 and then secured with a heat shrink sleeve, which would act as a thermally insulating cover. The printed circuit board 21 might extend beyond the ends 24a, 24b of battery 24. The portions of the printed circuit board 21 that extend beyond the ends 24a, 24b of the battery 24 may include apertures for use in mounting/securing the battery apparatus 11 in the emergency lighting apparatus 10.

Where a structural feature has been described, it may be replaced by means for performing one or more of the functions of the structural feature whether that function or those functions are explicitly or implicitly described.

Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon. l/we claim: