Electronic monitoring devices for perishable goods

Abstract

An electronic temperature indicator device includes temperature sensing circuitry adapted to provide a temperature signal and control circuitry adapted to monitor the temperature signal for at least one temperature-based trigger, and provide one or more output signals indicative of one or more of the at least one temperature-based trigger having occurred. The control circuitry is further adapted to: track a usage cycle of the device, detect a predetermined reset activity, in response to detection of the predetermined reset activity, update the usage cycle of the device to a subsequent usage cycle, and after the updating of the usage cycle of the device: monitor the temperature signal for the at least one temperature-based trigger, and provide one or more output signals indicative of one or more of the at least one temperature-based trigger having occurred during the subsequent usage cycle.

Description

Technical Field The present disclosure relates to electronic monitoring devices for perishable goods. The disclosure has particular, but not exclusive, relevance to electronic temperature monitors for perishable goods, and to auxiliary devices for such electronic temperature monitors. Background Electronic monitoring devices are used to monitor the storage and / or transport of a wide range of perishable goods including foodstuffs, sensitive electronic equipment, and pharmaceuticals. These devices are used, for example, to monitor conditions under which perishable goods are stored and transported, to ensure that the conditions under which the goods have been handled is acceptable. Some applications simply require the monitoring of duration of storage and / or transport. However, other aspects relating to conditions of storage and transport may be monitored, depending on the application. One aspect is the monitoring of temperature during storage and / or transport. Temperature monitoring devices for perishable goods generally fall into two categories, namely temperature loggers and temperature indicators. Temperature loggers have a primary function to provide a downloadable and / or printable report of a continuous log of the temperatures to which goods have been subjected during storage and / or transport. Temperature indicators have a primary function to be indicative of the occurrence of a temperature-based trigger during storage and / or transport, to provide a simple indicator of whether one, or more than one different, perishability threshold(s) have been exceeded at any time during the handling of the goods. An indicator provided may be irreversible so that the indication cannot be concealed or reversed by accident or by deceit. Such devices are in effect single-use. Chemical temperature indicators are relatively inexpensive, however not particularly accurate. Electronic temperature indicators are more accurate, but more expensive to manufacture. It would be desirable to make electronic temperature indicators more inexpensive, to make their use in a wider range of applications more economically viable. Summary According to a first aspect of the present invention there is provided an electronic temperature indicator device comprising temperature sensing circuitry adapted to provide a temperature signal and control circuitry adapted to: monitor the temperature signal for at least one temperature-based trigger; and provide one or more output signals indicative of one or more of the at least one temperature-based trigger having occurred, wherein the control circuitry is further adapted to: track a usage cycle of the device; detect a predetermined reset activity; in response to detection of the predetermined reset activity, update the usage cycle of the device to a subsequent usage cycle; and after the updating of the usage cycle of the device: monitor the temperature signal for the at least one temperature-based trigger; and provide one or more output signals indicative of one or more of the at least one temperature-based trigger having occurred during the subsequent usage cycle. By updating the usage cycle of the device in response to detection of the predetermined reset activity, the device allows the temperature signal to be monitored for the occurrence of one or more temperature-based triggers over different usage cycles. By providing output signals indicative of one or more temperature-based triggers, the device is able to indicate to a user of the occurrence of the trigger during a usage cycle of the device. According to a second aspect of the present invention there is provided an auxiliary device for an electronic temperature indicator device, the electronic temperature indicator device comprising temperature sensing circuitry adapted to provide a temperature signal and control circuitry adapted to: monitor the temperature signal for at least one temperature-based trigger; and provide one or more output signals indicative of one or more of the at least one temperature-based trigger having occurred, wherein the control circuitry is further adapted to: track a usage cycle of the device; detect a predetermined reset activity; in response to detection of the predetermined reset activity, update the usage cycle of the device to a subsequent usage cycle; and after the updating of the usage cycle of the device: monitor the temperature signal for the at least one temperature-based trigger; and provide one or more output signals indicative of one or more of the at least one temperature-based trigger having occurred during the subsequent usage cycle, wherein the predetermined reset activity involves a plurality of contemporaneous actions being performed, the plurality of contemporaneous actions comprising: a button press; and activation of a Hall effect switch, and wherein the auxiliary device comprises: a part configured to activate the button press; and a magnet configured to activate the Hall effect switch. By using an auxiliary device comprising a button pressing part and a magnet provides security to the performance of the predetermined reset activity. In particular, the use of an auxiliary device for performing the reset activity tends to ensure that only selectively authorised users, namely those in possession of the auxiliary device are able to update the usage cycles of the device. In particular, it can be assumed, at least to a reasonable level of certainty, that a usage cycle of the device, if subsequent to the first one, was initiated by a user in possession of the auxiliary device. According to a third aspect of the present invention there is provided an electronic monitoring device for perishable goods, comprising: sensing circuitry adapted to provide a signal; control circuitry adapted to receive the signal, to monitor the signal for a trigger during a current usage cycle of the device, and to provide an output indicating the trigger having occurred; an alarm condition indicator for indicating whether the trigger has occurred; and one or more usage cycle indicators configured to indicate the current usage cycle of the device, wherein the device is configured to power the alarm condition indicator and the one or more usage cycle indicators in an interlaced sequence associated with a predetermined frequency. By powering the alarm condition indicator and the one or more usage cycle indicators in an interlaced sequence, the total power delivered to the various indicators at a given time may be reduced. Nevertheless, by manes of a sufficient frequency of flashing of each LED in the interlaced sequence, a user of the device may be given an illusion that the indicators are displaying in an “on” mode without noticeable flashing. A preferred frequency of activation of an LED in the interlaced sequence is at least 5 Hz, preferably at least 15 Hz, and more preferably at least 30 Hz. According to a fourth aspect of the present invention there is provided an electronic monitoring device for perishable goods, the device being configured to reset the current usage cycle in response to detecting a predetermined reset activity, the device comprising one or more usage cycle indicators for indicating the current usage cycle of the device, wherein detecting the predetermined reset activity involves activation of a Hall effect switch. By relying on the activation of a Hall effect switch, the predetermined reset activity is provided a degree of security, such that the usage cycle of the device is updated only when the Hall effect switch is activated by an appropriately positioned magnetic device. According to a fifth aspect of the present invention there is provided an electronic monitoring device for perishable goods, the device being configured to reset the current usage cycle in response to detecting a predetermined reset activity, the device comprising: a set of two or more reset tabs, each tab in the set of reset tabs being configured to indicate a current usage cycle of the device, wherein detection of the predetermined reset activity involves detection of the performance of an action on one of the two or more reset tabs. By using two or more reset tabs, the device may be configured to have several usage cycles. By configuring the reset tabs to indicate a current usage cycle of the device, the predetermined reset activity may be associated with a specific physical part of the device. Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings. Brief Description of the Drawings Figure 1 shows a schematic diagram of an electronic temperature indicator device with a Hall switch; Figure 2 shows a diagram of an electronic circuit included in the device; Figure 3A shows a schematic an illustration of time-dependent temperature signals as monitored by the temperature indicator device that either satisfies or does not satisfy an acceptable operating condition for an example alarm trigger parameter; Figure 3B shows an illustration of time-dependent temperature signals for which the temperature indicator device either satisfies or does not satisfy the acceptable operating condition for another example alarm trigger parameter; Figure 4 shows a schematic diagram of an auxiliary device for the electronic temperature indicator device; Figure 5 A shows illustrative diagrams of the front view of two examples of the electronic temperature indicator device; Figure 5B shows illustrative diagrams of the front and back view of an example of an auxiliary device for a device of the type shown in Figure 5 A; and Figure 6 shows a schematic diagram of an electronic temperature indicator device with a set of reset tabs. Detailed Description Details of devices according to examples will become apparent from the following description with reference to the figures. In this description, for the purposes of explanation, numerous specific details of certain examples are set forth. Reference in the specification to ‘an example’ or similar language means that a feature, structure, or characteristic described in connection with the example is included in at least that one example but not necessarily in other examples. It should be further noted that certain examples are described schematically with certain features omitted and / or necessarily simplified for the ease of explanation and understanding of the concepts underlying the examples. Embodiments of the present disclosure relate to temperature indicator devices. Embodiments of the invention provide multi-usability in a low-cost, light-weight, and resource-friendly electronic temperature indicator device on which, or from which, an indication may be provided in an irreversible manner so that the indication cannot be concealed or reversed by accident or by deceit. Note that by irreversibly, it is meant that the indication may be entirely or substantially irreversible, or at least irreversible without a certain level of authority, which may involve an authority check. To provide devices which are multi-use, these embodiments make use of (i) an electronic switch arrangement including for example a Hall effect switch, and / or (ii) a set of two or more reset tabs, which can be used to detect reset activity functionality. The devices can thus be reset to update a usage cycle. Figure 1 shows an electronic temperature indicator device 100 comprising a number of components. The components may include temperature sensing circuitry 102 capable of sensing temperature. The temperature sensing circuitry 102 may, for example, include temperature sensors for measuring the temperature of the environment of, or of an object adjacent to, the temperature indicator device 100. For example, the temperature sensors may be capable of measuring either the temperature of a food, a pharmaceutical compound or product, or a medical product placed in the vicinity of the device 100, or the temperature of the container within which such products may have been placed for transportation or otherwise. The temperature sensors may be commonly used electrical temperature sensors such as, for example, thermocouples or resistance thermometers or thermistors. The temperature sensors may also include integrated circuit sensors involving a programmable interface. Temperature measurements may be made by the temperature sensors in real-time either continuously or at regular intervals. The temperature sensing circuitry 102 may be adapted to provide a temperature signal to control circuitry 104 based on the real-time temperature measurements from said temperature sensors. For example, the temperature signal may indicate values of the temperature of the environment as a function of time. The temperature values measured by the temperature sensors may be processed by the temperature sensing circuitry 102 to obtain the temperature signal. Figure 1 shows that the temperature indicator device further includes control circuitry 104. The control circuitry 104 may be adapted to monitor the temperature signal received from the temperature sensing circuitry 102 of the device. The control circuitry 104 may monitor the temperature signal received at regular intervals of time either continuously or at regular intervals. By monitoring the temperature signal in such fashion, the control circuitry may be able to determine whether one or more temperature-based triggers have occurred. The temperature-based trigger may correspond to the temperature signal exhibiting temporal or instantaneous characteristics that may have particular relevance to the use of the electronic indicator device 100. Upon determining whether at least one of the one or more temperature based triggers have occurred, the control circuitry 104 may provide corresponding output signals indicative of the occurrence temperature-based trigger. By providing such output signals, a user of the electronic indicator device 100 may be able to determine whether the predetermined one or more temperature-based triggers have occurred and may thereby take appropriate actions. The control circuitry 104 may comprise, for example electronic circuit components including a microprocessor and one or batteries for powering the circuit components. The control circuitry may comprise resistors, diodes and capacitors intended for executing the aforementioned functions. For example, the microprocessor may be preprogrammed to process a temperature signal and perform calculations on the temperature signal as a function of time to determine whether a temperature-based trigger has occurred. Similarly, the microprocessor may be preprogrammed to transmit output signals based on a determination of whether a temperature-based trigger has occurred or not during operation of the device. In some examples, the control circuitry 104 may comprise a memory unit for storing chunks of the temperature signal for monitoring and processing purposes. The control circuitry may also be equipped with, for example a long-term memory storage unit that is capable of storing a log of temperature-based trigger events for processing after the operation of the device. The indicator device 100 shown in Figure 1 may be associated with one or more usage cycles. For example, a usage cycle of the device 100 may correspond to a period of time during which the control circuitry 104 monitors the temperature signal to determine whether a temperature-based trigger has occurred. In the present context, it is desirable that the device 100 have multiple usage cycles corresponding to different periods of time during which one or more temperature-based triggers occur. For example, it may be desirable to separately determine whether a temperature-based trigger occurs during two separate instances of storage and / or transport of perishable goods, or a container of such goods, whose temperature is monitored by the indicator device 100. The control circuitry 104 may be adapted to track such usage cycles of the device over the lifetime of the device. Alternatively, it may simply be desirable to pause the tracking of the temperature signal for the occurrence of temperature-based triggers and continue tracking the temperature signal after a certain period of time, for example during an intervention by a user during which the temperature is not required to be monitored. In such cases as explained above, it may be desirable to reset the monitoring functionality of the control circuitry 104 after a first phase to separately monitor the temperature signal during a second instance of storage and / or transport. In order to reset the usage cycle of the device, the control circuitry 104 may be adapted to detect a predetermined reset activity from a user of the device. For example, a user such as an authenticated user at the end of instance of storage and / or transport and / or at the start of a subsequent instance of storage and / or transport may be provided with the capability to conduct the predetermined reset activity. Alternatively, a regular user of the device 100 may be able to conduct the predetermined reset activity. Upon detecting the predetermined reset activity, the control circuitry 104 may update the usage cycle of the device 100 to a subsequent usage cycle. In the subsequent usage cycle, the control circuitry 104 may resume or restart the monitoring process, so that the temperature signal is monitored once again for determining whether a temperature-based trigger has occurred. If a temperature-based trigger occurs during the subsequent usage cycle of the device, the control circuitry may provide output signals indicating that the temperature-based trigger has occurred. For example, if a different temperature-based trigger occurs during the subsequent usage cycle, the control circuitry 104 may provide outputs corresponding to the determination that those different triggers have occurred. In this manner, the indicator device 100 may be equipped with the capability of accumulating the occurrence of temperature-based triggers in different usage cycles of the device 100, thereby allowing the device 100 to be used over a series of usage cycles during the lifetime of the device 100. In addition to the examples described above, in some examples, the control circuitry 104 of the device 100 may be adapted to detect a predetermined start activity which corresponds to the initiation of a first usage cycle of the device. It may be desirable that the device 100 is switched on at a certain point in time before the monitoring process commences. For example, the device 100 may be switched on after securing the device to a product or product container whose temperature is to be monitored. In some examples, a user of the device 100 may be able to press a button to start the device 100, or the insertion of batteries in the device 100, which may be detected by the control circuitry 104 as predetermined start activities for initiating the first usage cycle. Figure 1 shows a button 110 which when pressed causes the control circuitry 104 to detect the predetermined start activity. Such example devices may be alternatives to “always-on” type of indicator devices. In some examples, it may be desirable that the device 100 be adapted to indicate the occurrence of temperature-based triggers in subsequent cycles. For example, it may be desirable that the occurrence of all of the one or more temperature-based triggers is reset after the predetermined reset activity is detected. This can be particularly useful when the device 100 is to be used on different products for example during the lifetime of the device. In such cases, the output signals indicative of the occurrence of the at least one of the one or more temperature-based triggers may correspond to the occurrence during the subsequent usage cycle and not indicative of the one or more temperature-based triggers having occurred during the first usage cycle. It is to be understood that many variations of the device 100 are possible, for example, including variations in which only of the one or more temperature-based triggers is monitored afresh in the subsequent usage cycle. In certain further examples, it may be desirable that the user inputs for starting the first usage cycle and starting a subsequent usage cycle are different. In such cases, the predetermined start activity may be different from the predetermined reset activity. As will be described further on, it may be desirable that the reset activity is performed by an authenticated user who has access to an auxiliary device, which is different from the device 100, and with the help of which the predetermined reset activity is performed. For example, in the distribution logistics of perishable goods, it may be desirable that only an authenticated user at the start of a new distribution phase has access to an auxiliary device, using which a subsequent usage cycle is initiated. As described above, the predetermined start activity may be different from the predetermined reset activity, and therefore the predetermined start activity may not require the use of the auxiliary device. The indicator device 100 may be equipped with a capability of tracking the usage cycles during the operation of the device. For example, the control circuitry 104 may be adapted to track a plurality of usage states defined such that updating the usage cycle of the device comprises updating the associated usage state of the device. By tracking a plurality of usage states, a user may be provided indication of the device 100 operating in a given usage cycle of the device. Tracking the plurality of usage states may also allow the control circuitry 104 to distinguish a current usage cycle of the device from a previous usage cycle of the device 100. In this manner, the control circuitry 104 may perform different sets of actions, such as providing the aforementioned output signals provided by the control circuitry in response to detecting the predetermined reset activity, each set corresponding to a different usage cycle of the device. Furthermore, in some examples, the device 100 may be designed for monitoring the temperature for a limited number of usage cycles. Such a limited number may correspond with, for example, the number of usage cycle indicators provided on the device. In such examples, the control circuitry 104 may be adapted to track a limited number of usage states. When this limited number of usage states are completed, the control circuitry 104 may inhibit updating the current usage cycle to a subsequent usage cycle in response to detecting the predetermined reset activity, including disabling the detection of the reset activity once the limited number of usage states have been completed. For example, the device may be designed 100 for use over five usage cycles. In that case, after the corresponding five usage states are completed, the device 100 may not initiate a subsequent usage cycle on receiving a relevant reset input from a user. Figure 1 shows the temperature indicator device 100 as including an indicator panel 106 comprising a usage cycle indicator 108 for indicating a usage cycle of the device. For example, the control circuitry 104 may be able to send a signal to the indicator panel 106 so that during operation of the device the usage cycle indicator may display the usage cycle of the device. In some examples, the usage cycle indicator 108 may be an LCD or a screen that displays the count or name of the current usage cycle of the device. Certain use cases of the device 100 may involve transmitting signals corresponding to the alarm condition indicator to a device connected remotely with the device 100, for example via Bluetooth (registered trademark). In some examples, the usage cycle indicator 108 may be capable of displaying other relevant information such as the remaining number of usage cycles where there a limited number of usage states are tracked by the control circuitry 104, or other tracked variables such as the time, battery life, etc. of the device 100. In some examples, a plurality of usage cycle indicators may be used as shown in Figure 1. Each usage cycle indicator may then correspond with a different display item, such as different usage states or different tracked variables of the device. By displaying the usage cycle of the device 100, the usage cycle indicator allows a regular or an authenticated user to determine that the outputs corresponding to the occurrence of temperature-based triggers correspond with the indicated usage cycle of the device 100. In this manner, the relevant user of the device 100 is able to ascertain that the associated temperature-based trigger had occurred during a time period corresponding to the indicated usage cycle of the device 100. This may be particularly useful for a user of a product at the end of a distribution phase, for example, who wishes to readily determine that the temperature-based trigger had occurred in the current phase of distribution without the burden of processing the output signals provided by the control circuitry 104. In this manner, identification of the occurrence of the temperature-based trigger during a usage cycle is simplified. In some cases, it may be desirable that the device 100 has a prolonged lifetime. For example, the device 100 may be battery operated and it may be desirable that the battery life is to be prolonged. In such cases, an LCD may consume a significant amount of power during operation, thereby reducing the lifetime of the device. In the event that the battery dies during a usage cycle of the device, an end user of the device will be unable to determine whether a temperature-based trigger had occurred during the usage cycle, and thereby unable to ascertain whether the product or its environment experienced certain unacceptable temperature changes during the usage cycle. To increase the battery life of the device 100, a set of usage cycle indicators each in the form of an LED may be used. For example, a single-color LED may be used for each of the set of usage cycle indicators. In some examples, the device 100 may comprise a plurality of LEDs corresponding to a different usage state tracked by the control circuitry 104. Alternatively, a single light emitting element may be used that exhibits different display patterns corresponding to different usage states. In this manner, an individual or a set of LEDs may be used to indicate the usage cycles. LEDs are well-known to consume a small amount of power during operation. Moreover, an LED is cheap and light-weight. Thus, by using a usage cycle indicator 108 comprising one or more LEDs, a low-cost and light-weight device 100 may be produced in comparison to other devices using other means of indicating the usage cycles. Another method of reducing the power consumed by a usage indicator 108, be it an LCD or an LED or otherwise, involves employing a reduced duty cycle of the usage indicator 108. For example, the control circuitry 104 may be configured to power the usage indicator or indicators either intermittently or at regular intervals of time to reduce the duty cycle of the indicators below 100%. As an example, the usage indicator 108 may be briefly powered once every few seconds or minutes or longer intervals. By employing a reduced duty cycle, the device lifetime can be significantly improved. Yet another method of improving the lifetime of the device 100 involves powering the usage cycle indicator 108 on demand. For example, the device 108 may comprise a button for interrogation of the device. In this example, the control circuitry 104 may be adapted to power the usage cycle indicator 108, or the multiple usage cycle indicators, when the button for interrogation is pressed. Thus, by pressing the button an “interrogation” of the device 100 may be performed to indicate the usage cycle of the device. The same button may be used for interrogation as the button 110 used for performing the predetermined start activity described earlier. For example, the predetermined start activity may involve pressing the button for a relatively longer than for the interrogation to be performed in order to differentiate the detection of the two separate activities. Alternatively, a different button may be used for interrogation. Further alternatives may involve not using a button but other means for performing the interrogation. In all such examples, by exclusively powering the usage cycle indicator 108 or indicators on the press of a button, the power use of the device 100 is considerably reduced in comparison to a continuous or intermittently powered device. Figure 1 shows a temperature indicator device 100 including a reset component 112, which may be a part of or be connected to the control circuitry 104, for performing the predetermined reset activity. One way of achieving this is to rely on the button 110 to perform the predetermined reset activity. For example, the button 110 may be pressed for a longer duration than required for performing the start activity. However, in such examples, the user may inadvertently perform a reset activity when intending to perform the start activity and thereby accidentally update the usage cycle of the device. It is therefore desirable to introduce an alternative means of invoke the usage cycle of the device to be updated. The attentive reader may find it conceivable to use a separate button for performing the reset activity than the button 110 used for performing the start activity. Yet, on the one hand, the proliferations of buttons may impose undesirable constraints on the size of the device. Perhaps more importantly, it is often desirable that an appropriate authenticated user of the device alone is able to perform the predetermined reset activity that updates the cycle of the device to a subsequent usage cycle. Alternatively, it may be desirable that a user of the device is able to trust that the usage cycle indicated by the device was not tampered when the device was not in their possession, for example, during transport of a product on which the device is secured. In either case, it is an objective of the present invention to provide a means of tamper-proofing a temperature indicator device capable of operating multiple usage cycles. The present application describes several examples of achieving this objecting. In one example, the reset component 112 of the control circuitry comprises a Hall effect switch 114. The Hall effect switch is a commonly used electronic circuit component that can be activated with a magnet. The working principle of the Hall effect observed in on a metallic plate have a finite width and connected to a circuit by its length-wise ends. When a magnet with a specified polarity is brought in proximity of the metallic plate while current is flowing along the length of the plate, a corresponding potential difference develops across the width of the metallic plate, thereby activating the switch. Since the Hall effect switch is activated when a magnet of specified polarity is brought in its proximity, the switch also serves as a proximity sensor. It is therefore be understood that, in the examples described herein, the Hall effect switch or switches may be replaced with a proximity sensor. In the example device 100 being described, the predetermined reset activity may involve the activation of the Hall effect switch 114 with a magnet. Thus, a user of the device may be able to activate the Hall effect switch in order to update the usage cycle of the device to a subsequent usage cycle. In this manner, the predetermined user activity may be performed only by a user having the magnet. In certain examples, the Hall effect switch may be placed inside the device 100 in an undisclosed location. Thus, the user may further require knowledge of the current placement of the Hall effect switch and polarity of the magnet to active the Hall effect switch. Such knowledge may be provided in advance to an authenticated user. In this manner, the predetermined reset activity may be secured from use by an unauthenticated user of the device. Alternatively, a free-standing magnet may be used in the production line of a product to update the usage cycle of an indicator device 100 secured to the product. In this manner, the Hall effect switch may be used to automatically update the usage cycle of the device 100 after one load of perishable goods has been distributed, for use with a further load or perishable goods. Nevertheless, in some use cases, the example described above may not lend sufficient security to the performance of the predetermined reset activity. In such examples, a plurality of Hall effect switches may be used as part of the reset component 112. The plurality of Hall effect switches may have a predetermined arrangement within the device making the concurrent activation of the Hall effect switches considerably more difficult without prior knowledge of the precise locations of the Hall effect switches. By relying on a Hall effect switch to perform the predetermined reset activity, the need for a long duration press of the button 110 for performing the start activity is precluded. Since the Hall effect switch 114 is only activated when a magnet of the correct polarity is brought in proximity of the device at a location corresponding to the placement of the switch, inadvertent updates of the usage cycle can be avoided to a greater degree. Figure 1 shows an example indicator device 100 comprising a further alternative means for performing the predetermined user activity. In this example, the reset component 112 comprises a button 116 and a Hall effect switch 114. As explained earlier, the reset component 112 may either be a part of or connected to the control circuitry 104 in some fashion. In such examples, the predetermined reset activity involves a plurality of contemporaneous actions being performed. These actions may include but are not limited to a button press and the activation of the Hall effect switch. The button 116 and the Hall effect switch 116 may be placed at any desirable location within the device 100. Thus, by requiring the button 116 to be pressed contemporaneously with placing a magnet of the correct polarity at a location appropriate for activating the Hall effect switch, the variables involved for correctly performing the predetermined reset activity are increased. Furthermore, in some examples, the Hall effect switch 114 may be placed close to or underneath the button 116 within the device 100. This may make it considerably more difficult to simultaneously activate the Hall effect switch 114 with a magnet while pressing the button 116 using a finger. To further increase the security of the predetermined reset activity for the example device 100, a plurality of Hall effect switches may be employed. The Hall effect switches may be arranged in a predetermined configuration. In this manner, the indication of the usage cycles is made more secure. Further, as will be explained below, an auxiliary device configured for the device 100 may be developed that allows the button and the activation of the Hall effect switch to be performed contemporaneously. In such examples, an authenticated user of the device may be provided with the auxiliary device in advance in order to perform the said predetermined reset activity. In all examples discussed herein, it is to be understood that the Hall effect switch or switches may be replaced by a proximity sensor. As explained above, a Hall effect switch requires current to flow through it in order to function. Continuously powering the Hall effect switch 114 or switches employed in the examples mentioned hereinbefore may therefore diminish the lifetime of the device 100. In some examples, the indicator device 100 may be configured to power the Hall effect switch 114 when pressing the button 116. By powering the Hall effect switch 114 exclusively when the button 116 is pressed, the power consumption by the Hall effect switch 114 during operation of the device 100 may be significantly reduced. In this manner, the lifetime of the device 100 may be increased. Figure 2 shows a circuit diagram showing components of the control circuitry 104. The control circuitry comprises a Hall effect switch Halil (corresponding to the Hall effect switch 114 of Figure 1) and a switch SWI (corresponding to the button 116 of Figure 1) for performing the predetermined reset activity. The diagram further shows a diode SD1 and a resistor R2, which may be used in alternative arrangements of the circuit. For example, in one use case the diode SD1 may be fitted in the circuit and, in an alternative use case, the resistor R2 may be fitted in the location indicated. When the diode SD1 is not fitted in the circuit and the resistor R2 is fitted instead in the location indicated, the Hall effect switch is powered at all times during operation of the device. Alternatively, when the diode SD1 is fitted in the circuit in the indicated location, the Hall effect switch Halil may be activated only when the switch SWI is activated. In this manner, the control circuitry 104 may be configured for different expected device lifetimes. As explained before with respect to other examples, it is to be understood that the Hall effect switch or switches may be replaced by a proximity sensor. Returning to Figure 1, in certain examples, the temperature indicator device 100 may have a predefined acceptable operating condition characterised by the temperatures being monitored. For example, the acceptable operating condition may be characterised by the temperature of a product (or product environment) whose temperature is being monitored exhibiting a temperature behaviour during a usage cycle of the device 100 which is predetermined to be acceptable. It may therefore be desirable that the indicator device 100 in such examples be capable of indicating whether the predetermined accepted temperature behaviour has not been exhibited. For this purpose, the acceptable operating condition of the device 100 may be associated with one or more alarm trigger parameters. Such parameters may include for example relevant threshold values relating to the behaviour the temperature signal provided by the temperature sensing circuitry 102. The indicator device 100 or, in some examples the control circuitry 104, may comprise a memory unit for storing the one or more alarm trigger parameters. In some examples, the control circuitry 104 may be configured to determine, in response to determining whether the relevant threshold values have been crossed, that the acceptable operating condition of the device has not been satisfied in respect of the corresponding alarm trigger parameter. In other examples, an alternative criterion may be evaluated for determining whether the acceptable operating condition of the device is satisfied. Such determinations may involve calculations on the temperature signal and the one or more alarm trigger parameter that may be performed using a processing unit included in the indicator device, or more specifically the control circuitry 104. In general, the processing of the temperature signal and the one or more alarm trigger parameters may involve evaluating instantaneous values of temperature in the temperature signal or involve time-dependent calculations on the temperature signal in relation to the one or more alarm trigger parameters. As a result, the processing unit may be capable of computing basic computational recipes such as if conditions, comparing values, searching, and sorting. For certain use cases, the processing units may be equipped with functionality to perform complex mathematical functions such as integrals and derivates. In examples the processing unit may be the same as the microprocessor included in the control circuitry 104. On determining that the predefined acceptable operating condition is not satisfied, the device 100 may be configured to cause the temperature-based trigger to occur. In some examples, the device 100 may include an alarm condition indicator to indicate the occurrence of the temperature-based trigger. In this manner, a user may be alerted to the acceptable operating condition of the device 100 not being satisfied during a usage cycle. As discussed in relation to the usage cycle indicator, certain use cases of the device 100 may involve transmitting signals corresponding to the alarm condition indicator to a device connected remotely with the device 100, for example via Bluetooth communication. Figure 1 shows an example of the device 100 comprising an alarm condition indicator 120. The alarm condition indicator 120 may be an LCD or a screen for indicating that the temperature-based trigger has occurred. For example, the alarm condition indicator may display an appropriate symbol, such as ‘or a word, such as ‘ALERT’, when the temperature-based trigger has occurred. In some examples, the alarm condition indicator may indicate or display the particular alarm condition parameter in respect of which the temperature-based trigger has occurred. This may help the discern or examine the temperature characteristics in respect of which the acceptable operating condition of the device is not satisfied during a usage cycle. This may allow the user to take appropriate actions, such as discarding a product whose temperature is being monitored or decide to continue use of the product. In some examples of the device 100, the alarm condition indicator may be an LED. For example, the control circuitry may be programmed to power the LED when the temperature-based trigger has occurred, allowing a user to ascertain that the acceptable operation condition of the device has not been satisfied in respect of one or more of the alarm trigger parameters. As explained in relation to usage cycle indicators hereinbefore, using an LED can reduce the cost, weight, and operational lifetime of the device. In further examples, a plurality of alarm status LEDs may be used corresponding to the occurrence of a respective plurality of temperature-based triggers each indicating the occurrence of the temperature-based trigger in respect of a different alarm trigger parameter. In such examples, the outer covering of the device 100 may indicate identifying information in respect of each temperature-based trigger alongside the appropriate alarm condition indicator. In this manner, a user of the device may be able to discern the device 100 does not satisfy the acceptable operating condition in respect of a different alarm trigger parameter during the usage cycle. As discussed earlier, improving the operational lifetime of the device is of considerable significance with regard to the temperature indicator devices discussed above. With increasing number of LEDs used on the device 100 for various purposes, the battery life may be significantly reduced. For example, the device may be equipped with a number of usage cycle indicator LEDs and a number of alarm status indicator LEDs. A number of techniques for reducing the power usage of each individual LED was discussed above when a single LED is powered. However, when multiple LEDs need to be powered, with each added LED the current “draw” from the battery is increased. Further, the resistance of a battery such as a coin cell battery is typically quite high and increases as the battery discharges. These two concurrent factors may lead to significant drops in the voltage of the battery during a usage cycle, and particularly after a prolonged period of use of the device. Exaggerated voltage drops such as these may cause the voltage supply to components of the control circuitry 104 to fall resulting in a number of undesirable events, for example memory corruption or uninstructed resetting of the microcontroller, or premature or inadvertent updating of the usage cycle, or a so-called “brown-out” event to occur. In such examples where multiple LEDs carry out indicator functions of the device, the device 100 may be configured to power the alarm condition indicator and the one or more usage cycle indicators in an interlaced sequence associated with a predetermined frequency. An interlaced sequence may involve a sequence of powering the individual LEDs, wherein each element of the sequence involves powering a single LED. In such examples, the interlaced sequence may be further associated with a frequency that is higher than the threshold frequency at the visual system of a human eye loses the capability to discern differences between the units of the sequence. By powering the individual LEDs in such fashion, a user of the device may recognise the LEDs to be simultaneously powered although they are in fact being powered in an interlaced sequence. This technique may result in further saving the precious battery life of the device. Using different alarm trigger parameters may widen the industrial applicability of the device 100. For example, in relation to pharmaceutical or medicinal products, it may be desirable that the temperature of the food product be maintained at or below a certain temperature during transportation as the constitutive chemicals may be disintegrate or expire when certain temperature levels are acquired. In such use cases, the alarm trigger parameter may correspond to a threshold temperature which when surpassed (i.e. the temperature, based on the use case, either acquiring higher or lower values than the threshold temperature) results in the occurrence of the temperaturebased trigger. Figure 3A shows two different temperature signals provided by the temperature sensing circuitry in relation to an alarm trigger parameter corresponding to a threshold temperature 322. The first temperature signal 324 exhibits considerable variation in temperature yet never exceeds the threshold temperature 322. Thus, the temperature signal 324 does not cause the temperature-based trigger to occur in this example. The second temperature signal 326, however, exceeds the threshold temperature 322 corresponding to the alarm trigger parameter at several instances of time. Hence, the temperature signal 326 causes the temperature-based trigger to occur. Similarly, in the food industry for example it may be desirable to indicate whether the products have not only crossed a certain threshold temperature, but retained a value beyond the threshold temperature for a predetermined acceptable period of time. More generally, and as is common in the art, a threshold value of the integral of the temperature signal over time (the time temperature integral, or TTI) may be the metric used for determining whether an acceptable operation condition of the device is satisfied. Figure 3B shows two different temperature signals being processed along with an alarm trigger parameter associated with such a metric. Both temperature signals can be seen to exceed the threshold temperature 322 for a significant period of time. However, the temperature signal 328 has a smaller integral over time (TTI) above the threshold temperature 322 as indicated by the diagonal lines (area under the curve and above the threshold temperature). In this respect, it may be determined that the value of the integral is smaller than a threshold value, thereby causing the temperature-based trigger not to occur. The temperature signal 330 exhibits a far greater integral (TTI) than that of the temperature signal 328. In this respect, it may be determined that the value of the integral exceeds the threshold value, causing the temperature-based trigger to occur. These are some demonstrative examples of appropriate alarm trigger parameters, and it is to be understood that a wide variety of alarm trigger parameters and associated calculations may be used to determine whether the acceptable operating range of the device 100 is exceeded during a usage cycle. In addition to the alarm condition indicators configured to indicate that a temperature-based trigger has occurred during operation of the device 100, the device 100 may also include a memory unity adapted to store time stamps associated with the occurrence of the temperature-based trigger. In some examples, the device may record the time corresponding to the occurrence of the temperature-based in respect of different alarm trigger parameters. Such information may be communicated after a period of operation of the device by probing the memory unit. For example, it may be possible to probe the memory unit after a battery powering the device 100 has died, so that information relating to the occurrence of the temperature-based trigger may be mined. In this manner, a user of the device may despite the exhaustion of the lifetime of the device, be able to determine whether and at which time the acceptable operating condition of the device was not satisfied. This may further help users of the device track the location or distribution phase during which the acceptable operating condition of the device was not satisfied. The examples discussed thus far describe a temperature indicator device capable of sensing the temperature of the environment of the indicator device. However, it is to be understood that the invention is not specifically tied to temperature indicator devices. For example, the device 100 may be configured to sense relevant environment variables such as humidity, pressure, particulate concentrations, light, shock, or even orientation and geo-location. Such a device may have sensing circuitry adapted to provide a signal corresponding to the environment variable being measured. For example, a humidity sensor or a pressure gauge or an aerosol detector may be included in the sensing circuitry for providing the signal. The temperature signal may then include measured values of the environment variable being sensed as a function of time. Akin to the temperature indicator device, such an environment monitoring device may comprise control circuitry for receiving the signal and monitoring the signal for the occurrence of a trigger during a current usage cycle of the device. The process of monitoring the signal may include a determination of whether an appropriate trigger has occurred, and the control circuitry of the device may be adapted to provide outputs indicating the occurrence of the trigger. Such outputs may be indicated by one or more alarm condition indicators. As discussed previously in respect of the temperature indicator device 100, the environment monitoring device may comprise one or more usage cycle indicators configured to indicate the current usage cycle of the device. The device may optionally include a number of features related to update the usage cycle of the device as discussed in relation to the temperature indicator device 100. As described previously, the device may be configured to power the usage cycle indicators and the alarm condition indicators in an interlaced sequence at a predetermined frequency such that a user of the device may perceive any activated indicators to be simultaneously powered. Figure 4 shows a schematic diagram of an auxiliary device 400 for the temperature indicator devices discussed thus far. As explained before, the auxiliary device 400 may be provided to an authenticated user of the device who may be trusted with performing the predetermined reset activity of the device 100. The auxiliary device 400 may include a reset section 432 that corresponds with the reset component 112 of the indicator device 100. The reset section 432 may be equipped with a part 434 configured to activate the button press in the indicator device 100, and a magnet 436 configured to activate the Hall effect switch 114 of the indicator device 100. The auxiliary device 400 may further include an indicator section 438 configured to be in alignment with the indicator panel 106 of the device 100 when the reset section 432 is brought in alignment with the reset component 112. Similarly, the auxiliary device may include an additional indicator section 442 configured to be in alignment with the indicator panel 118 of the device 100 when the reset section 432 is brought in alignment with the reset component 112. In this manner, the status of the one or more a usage cycle indicators 108 and the alarm condition indicators 120 is not obscured from a user performing the predetermined reset activity. Thus, a user can get valuable feedback from the device relating to the status of the alarm condition and usage cycle at the time of performing the predetermined reset activity. When the auxiliary device 400 is brought in alignment with the indicator device 100 such that the part 434 and the magnet are able to perform their designated functions, the device 100 may detect the predetermined reset activity and thereby update the usage cycle to a subsequent usage cycle. In this manner, the auxiliary device 400 may function as a selectively authorised device for causing the usage cycle to be updated. A user in possession of the auxiliary device 400 may be able to easily conduct the predetermined reset activity, whereas a user not in possession of the same may not. This allows the usage cycles of the indicator device 100 to be protected from being tampered. As a result, the temperature indicator device 100 can be used multiple times in a manner that allows an end user to authenticate that the usage cycle was not updated by an unauthorised person or inadvertently as the case may be. Figure 5A shows views of two examples of the temperature indicator device discussed thus far. The first example 500 comprises an indicator panel 546 for a usage cycle indicator, an indicator panel 548 for an alarm condition indicator, and component 550 for starting and reset usage cycles. The first example 500 also comprises a two-dimensional matrix code 552, such as a QR code, or a serial number configured to store information corresponding to a calibration certificate of the indicator device 500. The code 552 may provide relevant information to an auditor inspecting the temperature indicator device. Figure 5A shows a second example 554 of the device 100. The indicator device 554 comprises five LEDs 556 for indicating the usage cycle of the device 554, and the alarm indicator panel 552 comprising two alarm status LEDs 558. The component 550 is provided with a button 516 and a Hall effect switch 514 in close proximity to one another. The button 516 is configured to register a press when the component 550 is pressed externally by a user of the device 554. The outline of the examples 500 and 554 in Figure 5 A are shown as having a generally rectangular outline. In general, examples of the device 100 may have more complex outlines, for example keyhole outlines, which examples of the auxiliary device 400 may correspond with in order to be secured to the indicator device and thereby enable performance of the predetermined reset activity. For example, the device 100 may have curvilinear features in outline that necessitate that the auxiliary device is similarly shaped. This lends an additional degree of security to the aforementioned predetermined reset activity allowing only users possessing an auxiliary device with the appropriate shape to conduct the predetermined reset activity in a simple manner. Figure 5B shows an example of an auxiliary device 560 corresponding to an example 554 of the indicator device 554. In particular, the front view 570 and the back view 572. The auxiliary device 560 may generally be opaque in construction so that a majority of the indicator device 554 is obscured from the user performing the reset activity. The opaque construction of the auxiliary device 560 may also help obscure the configuration of any parts of the auxiliary device 560 required for performing the reset activity. The auxiliary device 560 is further shown as comprising five usage cycle windows 562 that allow the corresponding LEDs 556 of the indicator device 554 to be seen by a user when the auxiliary device 560 is secured to the indicator device 554. Similarly, the auxiliary device 560 has two alarm indicator windows 564 that allow the activation of any alarm condition indicator LEDs 558 on the indicator device 554 to be noted. The auxiliary device 560 also comprises a button press section 566, which may comprise indications for a user to press in order to perform the reset activity. The auxiliary device 560 is shown as comprising a locating flange 568, such as a skirt, attached to the device. The locating flange 568 may help locate or secure the auxiliary device 560 to the indicator device 554. The back view 572 of the auxiliary device 560 shows a part 574 that may be attached to the underside of the button press section 566. The part 574 is configured to press the button 516 of the indicator device 554 when the button press section 566 of the auxiliary device 560 is pressed by a user. For example, the part may be a “pip” or a protrusion that may press on the button 516 when the user is performing the reset activity. The back view 572 also shows a magnet 576 located in close proximity to the part 574. The magnet 576 is located in such a manner as to activate the Hall effect switch 514 of the indicator device 554 when the auxiliary device 560 is secured, or when the button 574 is pressed. The preceding examples describe particular examples of an electronic indicator device that are configured to update and indicate the usage cycle of the device 100. Some of these examples involved the use of a proximity sensor such as a Hall effect switch to facilitate a reset activity for updating the usage cycle. In this manner, a user of the device can authenticate the indicated usage cycle by providing a degree of guarantee that the usage cycle has not been updated in their absence, i.e. the device has not been tampered with. The present application conceives further methods of endowing tamper-resistance to the aforementioned functionalities of the device 100. Figure 6 shows a device 600 comprising temperature sensing circuitry 602 for providing a temperature signal, and control circuitry for monitoring the temperature signal. The device also comprises a button 610 connected to the control circuitry for detecting a predetermined start activity for initiating a first usage cycle of the device 600. In line with the examples discussed so far, the control circuitry may be adapted to process the temperature signal for the occurrence of a temperature-based trigger during a usage cycle of the device. The device 600 also comprises a panel 618 including alarm condition indicators for indicating the output of determining whether the temperaturebased trigger has occurred. The device 600 further comprises a set of reset tabs 676, each of which is connected to the control circuitry 604. The reset tabs may be individually operable elements that each require the performance of an action to be operated. In a rudimentary example, each reset tab in the set of reset tabs 676 may be frangible so that when a reset tab is broken-off in appropriate manner, the broken-off tab may be detected by the control circuitry 604 to detect a reset activity as being performed. In response to the control circuitry may be configured to update the usage cycle of the device. Each reset tab in the set of reset tabs 676 may be configured to two states, corresponding to an unoperated state and an operated state. Figure 6 shows a reset tab 678 (shown with solid lines) that has not been operated and a reset tab 680 (shown with dashed lines) that has been operated. In such cases, the reset tab may appear different to a user once operated so that the user may visually distinguish an operated reset tab from an unoperated reset tab. In other cases, the reset tab may be designed to exhibit a different tactile characteristic when operated so that the user may differentiate an operated from an unoperated reset tab through tactile sensation. In yet other cases, differentiation of an operated from an unoperated reset tab may require employment of alternative sensory perceptions of the user. Furthermore, the reset tabs 676 may each be configured to be operated once. Having been operated, an operated tab 680. For example, operation of the reset tab may involve detaching the reset tab from the device 600. In this case, a user may be able to recognise that the tab 676 has been operated as it has been detached from the device. By allowing a user to distinguish between the two operating states of each reset tab, the reset tabs 676 may serve to indicate a corresponding usage cycle of the device. In this manner, the device 600 is able to provide tamper-resistance to the predetermined reset activity. The examples above serve to demonstrate the practicality of using reset tabs or Hall switches in the manner explained to a range of devices not limited to temperature or environment monitoring. Use of appropriate tamper-resistant reset features such as described above may allow devices to authenticate a current usage cycle of the device or a component of the device. As an example, devices that include some of the features described herein may be applied to multi-use devices that monitor a generic trigger event during a usage cycle of the device. For example, an electronic monitoring device for perishable goods may be configured to reset the current usage cycle in response to detecting a predetermined reset activity. Such a device may comprise one or more usage cycle indicators for indicating the current usage cycle of the device, wherein detecting the predetermined reset activity may involve the activation of a Hall effect switch. In alternative examples, detecting the predetermined reset activity may involve two or more contemporaneous actions being performed, wherein the two or more contemporaneous actions comprise a button press and a Hall effect switch being activated. In yet further examples, an electronic monitoring device may rely on a set two or more reset tabs, each tab in the set of reset tabs being configured to indicate a current usage cycle of the device. In such examples, detection of the predetermined reset activity may involve detection of the performance of an action on one of the two or more reset tabs. Such reset tabs may for example be configured to change distinctly, and irreversibly, to a new state in order to facilitate indication of the current usage cycle. The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. For example, it is conceivable that alternative means may be used to indicate alarm conditions and / or usage cycles of the device. In examples such as these, wireless protocols such as Bluetooth or Near-field Communication (NFC) may be employed to read a temperature indicator signal. In such examples, a Bluetooth or NFC-enabled device such as a smartphone may be brought in proximity to the electronic temperature indicator device to perform the reading of the device and used to indicate alarm conditions and / or usage cycles of the device instead of, or in addition to, one or more indicators being located on the electronic temperature indicator device itself. Similarly, the device may use an LCD indicator to perform some or all of the functions of the usage cycle indicators and / or the alarm condition indicators. As a further example, it is conceivable that electrochemical display markers, that may each be individually activated in an irreversible manner, may be used to indicate alarm conditions and / or usage cycles on the device. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims. 5

Claims

1. An electronic temperature indicator device comprising temperature sensing circuitry adapted to provide a temperature signal and control circuitry adapted to:monitor the temperature signal for at least one temperature-based trigger; andprovide one or more output signals indicative of one or more of the at least one temperature-based trigger having occurred,wherein the control circuitry is further adapted to:track a usage cycle of the device;detect a predetermined reset activity;in response to detection of the predetermined reset activity, update the usage cycle of the device to a subsequent usage cycle; andafter the updating of the usage cycle of the device:monitor the temperature signal for the at least one temperature-based trigger; andprovide one or more output signals indicative of one or more of the at least one temperature-based trigger having occurred during the subsequent usage cycle.

2. An electronic temperature indicator device according to claim 1, wherein the control circuitry is adapted to:detect a predetermined usage start activity; andin response to detecting the predetermined usage start activity, initiate a first usage cycle of the device, preceding a given said subsequent usage cycle.

3. An electronic temperature indicator device according to claim 2, wherein after the updating of the usage cycle of the device the output signals are indicative of one or more of the at least one temperature-based trigger having occurred during the given subsequent usage cycle and are not indicative of one or more of the at least one temperature-based having occurred during the first usage cycle.

4. An electronic temperature indicator device according to claim 2 or claim 3, wherein the predetermined reset activity is different to the predetermined start activity.

5. An electronic temperature indicator device according to claim 4 wherein the predetermined reset activity involves the use of an auxiliary device, separate from the electronic temperature indicator device, whereas the predetermined start activity does not.

6. An electronic temperature indicator device according to any preceding claim, wherein the control circuitry is adapted to track a plurality of usage states and the updating of the usage cycle comprises updating the associated usage state.

7. An electronic temperature indicator device according to claim 6, wherein the control circuitry is adapted to track a limited number of usage states, following which updating of the usage cycle, in response to detecting the predetermined reset activity, is inhibited.

8. An electronic temperature indicator device according to any preceding claim, comprising a usage cycle indicator for indicating a usage cycle of the device.

9. An electronic temperature indicator device according to claim 8, wherein the usage cycle indicator comprises an LED.

10. An electronic temperature indicator device according to claim 8 or claim 9, wherein the control circuitry is adapted to power the usage cycle indicator at predetermined intervals during operation of the device.

11. An electronic temperature indicator device according to any of claims 8 to 10, comprising a button for interrogation of the device, wherein the control circuitry is adapted to power the usage cycle indicator when the button for interrogation is pressed.

12. An electronic temperature indicator device according to any preceding claim, comprising a set of two or more reset tabs, each tab in the set of reset tabs being configured to indicate a different usage cycle of the device, wherein detection of the predetermined reset activity involves detection of the performance of an action on one of the two or more reset tabs.

13. An electronic temperature indicator device according to any of claims 1 to 11, wherein the control circuitry comprises a Hall effect switch, wherein detection of the predetermined reset activity involves activation of the Hall effect switch.

14. An electronic temperature indicator device according to any preceding claim, wherein the predetermined reset activity involves a plurality of contemporaneous actions being performed, the plurality of contemporaneous actions comprising:a button press; and activation of a proximity sensor.

15. An electronic temperature indicator device according to claim 13 and 14, wherein the proximity sensor is the Hall effect switch.

16. An electronic temperature indicator device according to claim 14 or 15, wherein detecting the predetermined reset activity involves activation of a plurality of proximity sensors.

17. An electronic temperature indicator device according to claim 16, wherein the plurality of proximity sensors are Hall effect switches, each Hall effect switch being activated with a magnet.

18. An electronic temperature indicator device according to any of claims 14 to 17, wherein activation of a proximity sensor involves the proximity sensor being powered by performing the button press.

19. An electronic temperature indicator device according to any preceding claim, the device having a predefined acceptable operating condition associated with one or more alarm trigger parameters for determining whether the acceptable operating condition is satisfied in dependence on the temperature signal, the monitoring of the temperature-based trigger involving a determination of the acceptable operating condition not being satisfied, the device comprising:a memory unit for storing the one or more alarm trigger parameters;a processing unit for processing the temperature signal and the one or more alarm trigger parameters; andan alarm condition indicator for indicating whether the temperature-based trigger has occurred.

20. An electronic temperature indicator device according to claim 19, wherein the alarm condition indicator comprises an LED.

21. An electronic temperature indicator device according to claim 20, comprising a plurality of alarm status LEDs, each alarm status LED being configured to indicate a different temperature-based trigger having occurred in respect of a corresponding different alarm trigger parameter.

22. An electronic temperature indicator device according to any of claims 19 to 21, wherein the memory unit is adapted to store a time stamp associated with the temperature-based trigger having occurred.

23. An auxiliary device for an electronic temperature indicator device, the electronic temperature indicator device comprising temperature sensing circuitry adapted to provide a temperature signal and control circuitry adapted to:monitor the temperature signal for at least one temperature-based trigger; andprovide one or more output signals indicative of one or more of the at least one temperature-based trigger having occurred,wherein the control circuitry is further adapted to:track a usage cycle of the device;detect a predetermined reset activity;in response to detection of the predetermined reset activity, update the usage cycle of the device to a subsequent usage cycle; andafter the updating of the usage cycle of the device:monitor the temperature signal for the at least one temperature-based trigger; andprovide one or more output signals indicative of one or more of the at least one temperature-based trigger having occurred during the subsequent usage cycle,wherein the predetermined reset activity involves a plurality of contemporaneous actions being performed, the plurality of contemporaneous actions comprising:a button press; andactivation of a Hall effect switch, andwherein the auxiliary device comprises:a part configured to activate the button press; anda magnet configured to activate the Hall effect switch.

24. An electronic monitoring device for perishable goods, comprising:sensing circuitry adapted to provide a signal;control circuitry adapted to receive the signal, to monitor the signal for a trigger during a current usage cycle of the device, and to provide an output indicating the trigger having occurred;an alarm condition indicator for indicating whether the trigger has occurred; andone or more usage cycle indicators configured to indicate the current usage cycle of the device,wherein the device is configured to power the alarm condition indicator and the one or more usage cycle indicators in an interlaced sequence associated with a predetermined frequency.

25. An electronic monitoring device for perishable goods, the device being configured to reset the current usage cycle in response to detecting a predeterminedreset activity, the device comprising one or more usage cycle indicators for indicating the current usage cycle of the device,wherein detecting the predetermined reset activity involves activation of a Hall effect switch.

526. An electronic monitoring device according to claim 25, wherein detecting the predetermined reset activity involves a plurality of contemporaneous actions being performed, the plurality of contemporaneous actions comprising a button press and the Hall effect switch being activated.1027. An electronic monitoring device for perishable goods, the device being configured to reset the current usage cycle in response to detecting a predetermined reset activity, the device comprising:a set of two or more reset tabs, each tab in the set of reset tabs being configured 15 to indicate a current usage cycle of the device, wherein detection of the predetermined reset activity involves detection of the performance of an action on one of the two or more reset tabs.

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