WO2001023256A2

WO2001023256A2 - Method for the monitoring of storage temperature-time conditions of a product and temperature-time indicating device for storage conditions

Info

Publication number: WO2001023256A2
Application number: PCT/BR2000/000106
Authority: WO
Inventors: Alvaro Motta Marins Costa; Sylvio Marreca; Guilherme Da Costa Martins
Original assignee: Alvaro Motta Marins Costa; Sylvio Marreca; Guilherme Da Costa Martins
Priority date: 1999-09-29
Filing date: 2000-09-28
Publication date: 2001-04-05
Also published as: WO2001023256A3

Abstract

Method for the monitoring of storage temperature-time conditions of a product and temperature-time indicating device (1) for storage conditions. The present invention refers to a method for monitoring the perishable product storage conditions and, more particularly, to indicate the conditions of such storage as a function of the temperature and time of permanence of the product at that temperature. The present invention also relates to a temperature-time indication device (1) that operates according to this method.

Description

Method for the monitoring of storage temperature-time conditions of a product and temperature-time indicating device for storage conditions

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention refers to a method for monitoring the perishable product storage conditions and, more particularly, to indicate the conditions of such storage as a function of the temperature and time of permanence of the product at that temperature. The present invention also relates to a temperature-time indication device that operates according to this method. It is known in the state of the art to employ mechanical devices to indicate the storage conditions or perishable products, such as food, drugs and the like. Such devices, as described, for example, on patents EP 625,700, US 3,618,588, US 3,702,077, US 3,786,777,. US 3,844,718, US 4,664,056 and US 5,034,233, generally present one or more chambers, wherein is injected a colored temperature-sensitive substance. After freezing and subsequent defrosting of the products to which such devices are applied, and by action of dilatation of said substances, they "leak" from their respective original chambers and become visible, thereby indicating an improper storage condition. It can then be said that, in respect of said devices of the prior art, once a given temperature limit is exceeded, an indication of potential hazard or damage to the controlled product is displayed. It should be pointed out that in these cases the variable of permanence time under an improper storage condition is not taken into consideration.

Accordingly, basically two problems arise, viz. the lack of accurate temperature controlling and also the lack of controlling of the storage time condition. On the other hand, patent GB 1 ,437,928 provides a circuit that identifies the heat conditions and compares them with pre-established temperature upper and lower limits, being thereby capable of determining and indicating, in the case of a brake, when the maximum limit is exceeded or when the temperature is below a minimum limit, which could eventually jeopardize the operation thereof. However, also in this case, the time of permanence in a condition outside the range of the optimum one is also not considered. In general, all of the above mentioned devices and indicators summarize and limit the operation thereof (in a mechanical manner) to indicating a storage outside an optimum or limit condition, not being therefore possible to determine more accurate parameters, such as those that take into account the time during which the product has been kept in storage outside the optimum conditions. Finally, it should be pointed out that for many marketed products, particularly food and drugs, there is a need of indicating a combined storage, that is, one that takes into consideration not only the limit temperature, but also the time of permanence above or below that temperature.

For example, we could have a perishable product the optimum storage conditions of which require that it be maintained at a temperature below 0°C. However, its storage at a temperature of up to 10°C for less than one hour could still be an appropriate condition, while, in the event that the product is kept for any length of time under a thermal condition defined as being one at which the product should not be exposed even for 1 second, in this example, higher than 20°C, the product would suffer irreparable damage thereto, rendering it unsuitable for consumption. As can be seen from the state of the art, none of the devices under analysis is capable of verifying in an accurate manner such a combined condition of parameters for the storage of products.

Accordingly, it is an object of the present invention to provide a method to determine the storage conditions of products in relation to the time and temperature variables to which they are exposed. It is another object of the present invention to provide an indicating device, easily constructed and visible, capable of showing the instant storage conditions of a product, and also to inform in a continuous manner whether a product has been kept outside a given temperature range for a time longer than the pre-established one. More particularly, the present invention relates to a method to monitor the storage temperature and time conditions of a product, which instantly identifies the thermal conditions imposed on the product, comparing them with the pre-established threshold temperatures, indicating the "proper" storage condition, while the temperature thereof is within the range between such threshold temperatures, it being necessary to that effect to determine at least a range of temperatures exceeding those thresholds, and to each temperature range will correspond a maximum permanence time which, on being exceeded, will indicate that the product is in an "improper" storage condition.

BRIEF DESCRIPTION OF THE DRAWINGS The scope of the present invention will be best understood in the light of the appended drawings, presented by way of illustration and not as limitation of the scope of the invention, wherein: - Figure 1 (fig. 1) is an upper elevation view of the outer portion of the device, in accordance with the present invention;

- Figure 2 (fig. 2) is a side elevation view of the outer portion of the same device of figure 1 ;

- Figure 3 (fig. 3) is a block diagram representing the method, applied to situations wherein the "proper" range of temperatures for storage has been established as being the one "below" the threshold temperature (TL(1)). Said situations are considered as being the standard ones on this diagram;

- Figure 4 (fig.4) is a block diagram representing the method, applied to the particular situation wherein one wishes to monitor an interval established by predetermined thermal thresholds.; - Figure 5 (fig. 5) is a block diagram representing the method, applied to situations wherein the "proper" storage temperature range has been established as being the one "above" the threshold temperature (TL(1));

- Figure 6 (fig. 6) is the electronic diagram of one of the possible circuits, corresponding to the method now proposed; - Figure 7 (Fig. 7) is the representation of the logic flow of the circuit on fig. 6;

- Figure 8 (fig. 8) comprises explanatory drawings allowing an accurate understanding of the logic flow shown on fig. 7; and

- Figure 9 (fig. 9) is a block diagram similar to the fig. 3 with the valid period (PV) monitoring function in focus. DESCRIPTION OF PREFERRED EMBODIMENTS

In accordance with fig. 1 and fig. 2 mentioned above, fig. 2 generally represents the indicating device (1 ) according to the present invention, being basically composed of an electronic circuit and a battery (not shown), surrounded by a heat-resistant ceramic or plastic material. Such circuit can be comprised of: discrete components; or a micro- controller plus some discrete components; a general integrated circuit (IC); microprocessor or still and preferably a specific-application integrated circuit (ASIC). Said device is further provided with a temperature sensor (TM) (not shown) or the like as a constitutive element thereof, capable of detecting the ambient temperature at which the product is stored. As an alternate embodiment of the invention, the utilization of a heat-sensitive circuit, for example, a digital thermometer, widely known in the art is provided (in the event of employing an integrated circuit; microprocessor or a microcontroller) in lieu of the thermistor as discrete element. It also comprises a display located on the upper portion of the case, comprised of three colored LEDs (or other light- or sound-emitting devices or LCD devices) of different colors (Lg, Lb, Lr) the condition of which (blinking or off) indicates in some cases the previous and current situation of a product and, in other cases, only the" current condition, both as a function of the environmental storage conditions, as will be more clearly explained below. In addition, and for previous activation of the device, a triggering button (3) (fig. 1 ) is provided, acting directly on an SCR or similar device, the latter being fully known in the state of the art. Said SCR-based circuits are characterized in that they are unidirectionally actuated, that is, once actuated, it starts to feed a circuit connected thereto in a definitive manner, that can no longer be directly deactivated and that in this case is employed in order to prevent tampering with the proposed settings and also for other reasons that will be clarified herein below. Finally, the indicating device (fig. 1 ) may be attached to the product to be monitored, employing any known attachment means, such as, for example, wires and cords, loops or gluing, among others, preferably opting for the one that best fits the packages or the product itself. Anyway, the important thing is to suggest that the temperature-time indication device be attached to the product in question in an external location thereof, so as be easily seen by the consumer. However, such suggestion does not preclude the attachment of the device where it is most convenient.

The monitoring method now proposed according to the present invention can be best seen on the diagram of fig. 3, which represents a situation considered as a standard one, which occurs most often, the other being merely variations or, more specifically, inversions or combinations thereof (as shown on figures: fig. 4 and fig. 5). The situation characterized as the standard one is that wherein the optimum temperature range for storage and preservation of a product is "below" the threshold temperature (TL(1 )); accordingly, any higher temperature is improper for such storage. In a first stage, shown as block 10 (fig. 3) the operation of the device is started by means of the pre-activation button (3) (fig. 1 ), connected to a circuit based on the SCR operation principle. It is important to emphasize that, on performing the definitive project of the integrated circuit (appropriate to the desired application), many other devices similar to an SCR and widely known in the art can be employed for pre-actuation of said device. If microprocessors or micro-controller are used this condition is performed by programming. Upon pre-activation of the circuit, a temperature sensor (TM) of block 1 1 continuously reads the ambient temperature T, the latter being compared to a threshold temperature (TL(1)) on the comparator block 12. Said threshold temperature (TL(1)) is preprogrammed and indicates (in the standard case) the temperature below which the product should be kept in order to safeguard the parameters established as "proper" for the storage and maintenance of its characteristics, until it is effectively consumed.

Accordingly, in the event that the temperature T measured on block 1 1 is higher than the threshold temperature (TL(1 )), the operation indication LEDs (or devices) Lg, Lb and Lr are kept off (block 15), thereby indicating that the temperature-time indicating device still isn't operating, even though it is pre-activated. It should be emphasized that once the response of the comparison made on block (12) is positive, the task provided by block (15) is never again repeated, this being a particular feature of the circuit, viz.: on being started, and at the first time (and only then) that a temperature below the threshold temperature is reached, the circuit starts to be fully fed, starting the effective monitoring function. Before this operation, the circuit is hibernating, feeding only blocks (1 1 , 12, 13, 14 and 15) thereof on the diagram, thereby providing a considerable energy saving, since only a portion of the circuit is being fed. In addition, and importantly, commanding the monitoring process to start only when the product is exposed to the temperature range predetermined as being the "proper" one for the storage thereof. From the moment when the ambient temperature (T) starts to be lower than the threshold temperature (TL(1)) on comparator block (16), a second condition is tested, of whether the measured temperature (T) is higher than such threshold temperature (TL(1 )). If a negative response results from this comparison, that is, (T) is lower than or equal to (TL(1 )), the green LED Lg is lit on block (17), indicating that the product is within the normal conditions, the optimum storage conditions. Accordingly, a loop operation results, which is maintained until the previous condition (on 16) no longer occurs, that is, the ambient storage temperature (T) becomes higher than the threshold temperature (TL(1)).

In this new condition (block (16) positive), on the following block (19) the green LED (Lg) goes off and the blue LED (Lb) goes on, indicating that the product is outside the optimum storage conditions.

On block (21 ), after block (20), the time counter is actuated (TIMER ON), which starts to record the time the product is being kept in an improper temperature storage condition. On the following comparator blocks (22, 25, 28 and 31 ), the product storage temperature (T) is initially compared with a new condition, that is, the threshold temperature (TL(n)). Such temperature (TL(n)) or, better still, the range of temperatures defined thereby (from TL(n) to infinity) should be considered as being a maximum, to which the product should never be exposed, not even for a brief moment, this range being preferably given a permanence time (tL(1 )) very close to or equal to zero. Particular attention should be given to comparator block (22); it initially tests the condition (T>TL(n)), wherein it is verified whether the temperature (T) at which the product is being stored is above the threshold temperature (TL(1 )). If the response of block (22) is positive, the operation proceeds to block (23), wherein the permanence time (t) in the thermal condition circumscribed by (22) is compared with a pre- established threshold time (tL(1 )). If the response of block (23) is negative, the instruction of block (24) is performed, wherein the relative time (tr(1 )) of permanence of the product under the thermal circumstances circumscribed by block (22) is accumulated, this relative time being summed (on block 36) to other eventual ones from blocks (27, 30, 33 and 35). Subsequently, a comparison is made on block (37) of whether the sum of the relative times (Str) on block (36) is greater than or equal to one (1 ), one (1) being the relative threshold time (tLr) pre-established as the maximum permanence time of the monitored product under the improper storage conditions. To that effect, it is necessary to understand that the maximum relative time (tr) is the permanence time (t) in relation to the maximum permanence threshold times (tL1 ), tL(2), tL(-), tL(n-1 ) and tL(n) for the product for each range of improper storage temperatures. It is important to emphasize that the longer threshold time is (tL(n)) and this only takes place in the most favorable adverse condition, that is, the range of temperatures established on block (16) or, better still, the temperatures comprised between the threshold temperature (TL(1)) and the threshold temperature (TL(2)), this range being therefore attributed the longest possible permanence time. If the response on block (37) is negative, a new reading is made on block (1 1 ) and, if the product is being maintained at the same temperature, there will be a loop operation until the thermal conditions imposed on the product are no longer equal to the positive ones of blocks (16 or 22).

If these conditions remain unaltered, the operation returns to block (22) which, still with a positive response, directs the flow to block (23) which, this time, if the entire time (tL(1)) is elapsed, turns the blue LED (Lb) off and lights the red LED (Lr) on block (38), thereby indicating in a definitive manner, that the product has been exposed the thermal storage conditions harmful to the integrity thereof. Block (38) ends the activation of the device, with the red LED (Lr) remaining on whatever the temperature to which the product is subjected upon verification of this condition. On the other hand, and in relation to block (22), in the event that the measured temperature (T) is not higher than (TL(n)), it will be then compared on block (25) with a second temperature threshold (TL(n-1 )), the latter being smaller than (TL(n)). In the same manner, in the event that said temperature is higher than (TL(n-1)), the operation proceeds to block (26), wherein the permanence time (tL(2)) in this new condition is tested. Accordingly, when the permanence time (t) exceeds the time limit

(tL(2)), the operation proceeds to block (38), wherein the red LED (Lr) is turned on and the blue LED (Lb) is turned off. This conditions, as previously described, definitively indicates that the product is or has been under improper and harmful storage conditions. The operation in these and in the following blocks (28-29, 31-32) is always the same, where basically the permanence time within a given temperature range above the threshold temperature (TL(1 )) is tested. Said temperature ranges are determined by the threshold temperatures (TL(1), TL(2), TL(-), TL(n-1 )), TL(n), and, as illustrated, (TL(n) > TL(n-1 ) > TL(-) > TL(2) > TL(1 )). For each of the temperature ranges, a maximum permanence time is associated, respectively (tL(1), tL(2), tL(-), tL(n-1) and tL(n)); considering that (tL(1 ) < tL(2) < tL(-) < tL(n-1 ) < tL(n)). In summary, and as a general rule, the largest the distance between the temperature range and the threshold temperature (TL), the lower is the possible permanence time of the product in this temperature range.

It is important to point out that under actual utilization circumstances, a product can be subjected to several different temperatures outside the optimum temperature range for preservation thereof; in this case the random transit of temperatures in the sets of comparator blocks (16-34, 22-23, 25-26, 28-29 and 31-32) is seen (in the course of threshold time (tL)). The elapsed relative times (tr(n), tr(n-1), tr(-), tr(2), tr(1)), particularly in each of these sets of blocks, are accumulated on blocks (24, 27, 30, 33 and 35), and when the value resulting from the sum of these relative times (made on block 36) in all sets of blocks through which the ambient temperature (T) has passed is reached or exceeded (positive circumstance of block (37)), the operation automatically goes to block (38), where the improper storage is definitively shown through the red LED (Lr) on. Finally, and in the event that the product returns to its optimum storage temperature, before any of the times previously tested on blocks (23, 26, 29, 32 and 34) is exceeded, and also the sum of the relative times (tr) on block (37), the logical response on block (16) will be no, whereby the operation goes to block (17), wherein the time counter is turned off and the already elapsed time is maintained therein, and also the blue LED (Lb) is turned off and the green LED (Lg) is turned on. Subsequently, the operation returns to block (11 ), where a new reading is made, and subsequently the operation goes to block (12), so that the temperature (T) is tested in relation to the threshold temperature (TL(1 )), as previously explained.

Even though the relative times remain accumulated, even in the event of a return of the product to the optimum storage temperatures (a situation described on the previous paragraph), it will be possible to zero the relative time accumulators (blocks 24, 27, 30,

33 and 35) if the option shown on block 18 is employed. Upon selection of the option, in each transit of the controlled product from an "improper" to a "proper" temperature range, the relative time accumulator will be zeroed, resulting in the re-establishment of all original threshold times (tL(1 ), tL(2), tL(-), tL(n-1 ) and tL(n)). In addition, and as illustrated, the temperature comparator blocks (16, 22, 25, 28 and

31) as well as those associated thereto, the threshold time comparator blocks (23, 26, 29, 32 and 34) may exist in a widely variable number, there being a greater control accuracy with a larger number of comparison parameters; however, at least one block should exist. The determination of temperature ranges by means of threshold temperatures (TL(1 ), TL(2), TL(-), TL(n-1 ) and TL(n)) are factors that should be programmed into the system before the start of its operation, and are exclusively a result of the characteristics of the product that is being controlled. Blocks (28, 29 and 30) represent, by means of (-), the countless threshold temperature ranges and their corresponding threshold and relative times that can be programmed in the system, so as to allow a greater or smaller control accuracy. In a similar manner, the permanence times determined for each of the ranges can be directly established at the time of programming of the circuit on fig. 3, and can be also automatically calculated by the same circuit, provided that a proper equation is inserted in the programming thereof, corresponding to the manner whereby one wishes to control the product, when the latter is subjected to temperatures outside to its optimum conservation range. These permanence times are also basically a result of the intrinsic characteristics of the product being monitored; accordingly, there is no way of establishing a general rule or even a comprehensive calculation, due to the diversity of unique conditions present in the universe of products that can be monitored. One should emphasize what has been previously said in respect of the attention that should be given to block (22), since it deals with the temperatures the product could not bear, even for a brief moment. Accordingly, a time constant (tL(1 )) equal to zero should be preferably associated to this temperature range, so that when said temperatures are reached, the circuit immediately indicates the improper storage condition, by activating the device (Lr) in an irreversible manner. In a simultaneous and optional manner, in the normal course of all operations, such method allows the monitoring of the valid period of the product to which the device is affixed (see fig. 9).

Said monitoring will take place by means of any time unit counter, fully known in the state of the art (65) and (65'), the operation of which will depend on information on the final date corresponding to the valid period (PV) of the product. Such information should be previously inserted in the time unit counter program, the units being a number of minutes (or any other time unit) corresponding to the desired valid period. By way of example, to a valid period of 480 days, approximately 4 months, will correspond a number of 172,800 minutes. In some special cases, of applications where one wishes to indicate a specific hour of a given day of any month, a "real-time clock" could be applied, and to that effect it suffices to program the clock with such information.

The valid period can be monitored in two manners: a) option 1 (fig. 9), where the time counter (65) is inserted after block (10"), meaning that the start of counting of the valid period will start simultaneously with the pre-activation; b) option 2 (fig. 9), where the time counter (65) is inserted between the block (16") and (17"), meaning that the valid period counting will start simultaneously with the effective activation.

In both cases, the operation is the same. Blocks (65) and (65') represent the time counter, and on blocks (66) and (66') the elapsed time (P) is compared with the valid period (PV). As long as the response in (66) and (66') is negative, there is a loop operation, until the response becomes positive, thereby indicating that the valid period has expired, on which occasion the operation goes to block (38), where the red LED (Lr) is turned on in an irreversible manner.

In respect of the consumer, the manner of displaying the various storage conditions is quite clear, which prevents wrong interpretations on his/her part. Accordingly, when the green LED (Lg) is on or blinking, this is an indication that the product is apt for use (or consumption) and is stored within the proper storage conditions for preservation thereof. When the blue LED (Lb) is on or blinking, this is an indication that the product, in spite of being stored outside the pre-established optimum temperature storage standards, is still apt for use or consumption. Finally, when the red LED (Lr) is on or blinking, this will indicate that the product has been exposed to a thermal condition entirely improper for preservation, whereby the characteristics thereof may have been irremediably altered or even that its valid period has expired.

In the event that all LEDs are off, maximum attention should be given to this condition, since this may indicate that the controlling device may not have been turned on, or may have operated for a long period of time, potentially well beyond the product's valid period.

Finally, the method also allows in an extremely easy manner to alter the scope of actuation of the present device, so that the latter may control the "improper" storage conditions, below a given thermal threshold, and to that effect it is necessary to make small alterations in signals, such as those evidenced on blocks (12', 16', 22', 25', 28' and

31' ) of fig. 5. Where on fig. 3 is read (>) and (+), on fig. 5 should read (<) and (-). In every other aspect, the circuit's logical behavior is analogous to the standard situation, in every detail thereof. By way of supplementation and demonstration of the possibilities of application of such method, in particular cases, see fig. 4, which represents the case when one intends to monitor the storage by means of two thermal thresholds, that is, an upper threshold represented by (TLs(1)) and a lower threshold, represented by (TLi(1)). In said case, the improper temperature ranges are respectively above and below said thresholds, the interval being encompassed by such thresholds, and is the optimum range of temperatures for preservation of the product. To that effect, it is necessary to pre-establish the following magnitudes: a) maximum lower limit time of permanence (tLi(1 )) relating to the maximum lower threshold temperature (TLi(n)); b) maximum upper limit time of permanence (tLs(1)) relating to the maximum upper threshold temperature (TLs(n)); c) lower limit time (tLi(n)) of permanence relating to the range of temperatures defined by the lower threshold temperature (TLi(1 )); d) upper limit time (tLs(n)) of permanence relating to the range of temperatures defined by the upper threshold temperature (TLs(1 )); e) all limit times (lower and higher) and their respective threshold temperatures desired between the magnitudes mentioned on items (a), (b), (c) and (d), above. Any values could be given to these magnitudes, even automatically, it sufficing to that effect to provide the circuit with the proper formulae for the intended purposes, as previously described in respect of the standard case.

It is important to point out that the magnitudes (TLi(n)) and (TLs(n)) above encompass the maximum temperature ranges (lower and upper) to which the product should never be exposed, even for a brief moment and which should be preferably given values equal to or very close to zero to their respective limit permanence times, tLi(1 ) and tLs(1).

The elapsing of any of the limit times in their respective temperature ranges improper for storage, both upper and lower ones, will be computed by independent timers (TIMER 1) and (TIMER 2), respectively. The situation now shown on fig. 4 is nothing else than the communion of the situations described on fig. 3 and fig. 5. Accordingly, the devices shown in this variation of the method, are capable of monitoring an enormous range of products that depend on an effective monitoring of two thermal extremes.

In respect of the consumer, the manner of displaying the various storage conditions is exactly the same shown in the standard situation. As a second scope of the present invention and in the light of the previous explanations required for elucidation of the method (first scope of the present invention), see below the description of operation of one of the possible indicating devices for control of the temperature-time storage conditions of a product, based on said method. This second object of the present invention will be best understood upon examination of the appended figures (shown by way of illustration and explanation, and not as a limitation of the extent of the invention), wherein: - Figure 6 (fig. 6) is an electronic diagram of the circuit;

- Figure 7 (fig. 7) is a representation of the logic flow of the circuit; and

- Figure 8 (fig. 8) are explanatory drawings, so that the logic flow shown on fig. 7 can be accurately and clearly understood. In accordance with fig. 6, fig. 7, fig. 1 and fig. 2 described above, on fig. 1 and fig. 2 is generally shown the indicating device in accordance with the present invention. Said device is comprised of battery-powered electronic circuit, with a luminous display, totally encapsulated in a thermally-resistant material, of regular monolithic shape and intended for a single use (discardable), the scope of which is to indicate whether a given product (to which it is attached) was or is being submitted to predetermined "proper" or

"improper" temperatures for maintenance and preservation thereof. Upon completion of the task for which the product is intended, it cannot be used again and, in addition, since it is specifically tailored (programmed) for a given product, it cannot be employed with another. Its useful life should always be greater than the valid period of the product to which it is applied.

Upon definition of the product to be monitored, for configuration of the indicating device it is necessary to pre-establish the magnitudes defined below:

1) Threshold temperature (TL) - temperature from which the product is exposed to "improper" conditions for maintenance of the integrity thereof. 2) Time Limit (tL) - the time in the course of which the product may remain exposed beyond the threshold temperature (TL) without irreversible alteration of the conditions required for maintenance of its integrity.

In addition to the above requirements, it is important to make a proper selection of: 1 ) the thermistor (TM2) which, in the particular case of fig. 6, should have an NPC (negative thermistor coefficient), with a characteristic curve corresponding to the behavior one intends to provide to the course of the time limit (tL) and; 2) the range of temperatures, which will be considered as being the "proper" one for preservation, whether above or below the threshold temperature (TL). On fig. 6, the "proper" one is that below the threshold temperature (TL). The operation of the device now proposed will be best understood upon an analysis of n,'i the indications shown by its display, one by one:

Said display is comprised of three LEDs: one green, one blue (or yellow) and one red, where the following conditions can be shown: a) three LEDs off; b) green LED blinking; c) blue LED blinking; d) red LED blinking; and e) green and red LEDs blinking.

Before subjecting the product to temperatures below or equal to the threshold temperature (TL), the device is not activated, a circumstance wherein the display shows the condition (a), that is, three LEDs off, this being the ideal condition for attachment of the device to the product to be controlled. When in the course of the process, the ambient temperature (T) reaches a value lower than the pre-established threshold temperature (TL), the condition (b) is shown on the display, that is, green LED blinking, showing that the product is at a "proper" temperature range for preservation thereof, also evidencing that the device is effectively activated. With this conditional effective activation system (12) only becomes operational when the ambient temperature is within a temperature range pre-established as being the proper one for preservation and storage of a product to be monitored, considering such fact as a safety factor for both the device and the product. In the case of the device, for the reason of ensuring that, should it be accidentally pre-activated at improper temperature ranges, it would never display such situation or effectively start the control process, and also, even when such accident occurs, with pre-regulated devices having very small limit or even zero limit times, there is no need to discard them for instantaneously showing an irreversible situation. And, for the product to be monitored, the condition is visible, as it requires that the monitoring only take place after the product is exposed to optimum storage temperature conditions; thanks to this, the device can be applied to the product under environmental conditions favorable to the applicators, without unnecessarily exposing them to extreme and harmful temperatures.

In the event that the ambient temperature is subsequently raised to a level exceeding the threshold temperature (TL), the display changes the previous condition, giving a new alarm in respect of the situation, characterized now by condition (c), of blue LED blinking, thereby indicating that the product is within an "improper" temperature range for preservation thereof.

This situation being reached, the limit time count (tL) is automatically started. In the course of the limit time (tL), it is possible to revert to the previous state, it sufficing to that effect to re-establish the optimum thermal storage conditions, in other words, by decreasing the ambient temperature down to a level lower than or equal to the limit temperature (TL); however, the return to the optimum level should take place before the limit time (tL) has elapsed. In this event, the (c) condition, of blue LED blinking is removed, being replaced by the (b) condition of green LED blinking and, in addition, the limit time counter (tL) is zeroed or accumulated, depending on the convenience thereof. However, if the limit time has elapsed, the product being at an improper thermal level for storage thereof, the display indicates a new situation, (d), characterized by a red LED blinking in an irreversible manner, thereby evidencing that the product is unsuitable for consumption or use.

Finally, upon occurrence of condition (e), represented by green and red LEDs blinking, this can be carefully interpreted as a fraud, that is, in the event that the product to be monitored is a frozen food, this condition would evidence the re-freezing of such product. However, this condition (e) can be suppressed, if necessary.

Nevertheless, there will be cases wherein, for reasons inherent to the product, it is not necessary to employ the limit time (tL), and in such situations the (c) condition, of blue

LED blinking, is not necessary and can be suppressed, and the display will show only conditions (a), (b), (d) and (e).

Note: In respect of the consumer, a special attention is required in the event that upon activation of the device the display shows again condition (a), that is, three LEDs off, which occurs in only two events: 1) the device's batteries are discharged; and (2) the device is damaged. In the case of the first event, one should verify the valid period of the product to which the device is attached and, in the case of the second event, one should verify the integrity of the device's outer portion, looking for visible damage. In both events, the product should not be purchased.

It is of paramount importance to clarify that the device of the present invention merely indicates whether a given product to which it has been attached was subjected to improper thermal storage conditions, and never evaluates the quality of such product; quite the opposite, the scope thereof is to indicate whether the quality of such product should be verified.

The scope and operation of the device being understood, we refer to the technical explanations relating to fig. 7, where the components and logic flow of operation of the circuit corresponding to the scope of the invention are detailed.

Fig. 6 represents the circuit where it is intended that the product to which the device will be applied has its range of preservation temperatures "below" the threshold temperature

(TL).

The description below refers to fig. 7, which presents the logic conditions imposed to the circuit by certain thermal "situations". The description of the logic operation is simple and is based on such "situations" which, being four in number, cover all possible events.

However, for a proper interpretation of the text, it is necessary to understand the symbols shown on fig. 8.

On "drawing A" on fig. 8, is a rectangle divided into four equal parts or blocks. In the course of the explanation, on fig. 7, each of these parts or blocks will correspond to one of the possible logic conditions described on drawing B, fig. 8. The first division relates to "situation 1", the second division to "situation 2" and so on and so forth. Accordingly, one can follow the entire logic behavior of the circuit, depending on the "particular situation" imposed on the thermistor (TM1).

In the description of the circuit, it is important to know that the "situations" are presented in the theoretical order of their occurrence.

The signaling represented by the blocks of fig. 8 are, on fig. 7, always at the inputs and outputs of the logic components (And gates, Not Gates and comparators).

Where the description of the circuit refers to a given "situation", let us say, "situation 1" , only the first divisions or blocks of the sequence of four will correspond thereto. Accordingly, the second, third and fourth divisions or blocks do not refer to "situation 1", and should be disregarded in the analysis of this particular situation.

For a proper understanding, the reading of the text should be accompanied of observation of fig. 6, fig. 7 and fig. 8.

ADJUSTMENT: The threshold temperature is adjusted by means of potentiometer (P1 ). Such adjustment depends on adaptation of the values of resistors (R1 ), (R2), R3) of potentiometer (P1 ) and of thermistor (TM1 ) to what is intended to determine, such as

"proper" and "improper" temperature ranges to be controlled.

The limit time is adjusted by means of thermistor (TM2). For such adjustment, it is necessary to adapt resistance (R15) and capacitor (C2) to what should be established as maximum limit time. The selection of thermistor (TM2) is intimately related to the behavior one wants to impose in the course of the limit time, this time being a function of the ambient temperature. >From then on, the characteristic curve of the selected (TM2) will impose the corresponding limit times to the temperatures detected thereby. OPERATION:

Note: The pre-activation system may or may not be included in the circuit.

The pre-activation system is comprised of an SCR (SCR1 ) having as a function to enable power to the circuit, and to that effect it suffices to apply a pulse to the gate (G).

As long as said SCR is not triggered, the circuit is permanently inactive. The description of operation of the circuit is done in accordance with the following four situations:

SITUATION 1 - Device pre-activated but turned off.

This is the initial condition, wherein the device is disabled.

The temperature imposed to the thermistor (TM1 ) being above the threshold temperature, a low resistive value is obtained therefrom, thereby implying a voltage on input 2 of comparator (A), lower than the reference voltage applied on input 1 (determined by (R2) and (R3)), generating a low logic level on output 3 of the same comparator. Accordingly, three LED turned off are obtained on the display. SITUATION 2 - Device automatically activated by temperature below the threshold temperature. When the temperature imposed to thermistor (TM1) is decreased to values lower than the threshold temperature, the device is activated and from then on, a high logic level is obtained on input 2 of comparator (A) which, on being compared to the reference voltage on input 1 of the same comparator, generates a high logic level on output 3 thereof and on input 1 of the And gate (I), the latter, in turn, having input 2 already fed by a pulsing logic level, originated from clock (CI6), causes the activation of the green

LED (LD2), which starts to blink. The green LED blinking condition appears on the display.

Simultaneously, the same high logic level from output 3 of comparator (A) appears on input 2 of comparator (C). Said voltage is compared with the reference voltage on input 1 of the same comparator, obtaining as a result a high logic level on output 3 thereof and on input 1 of the And gate (G). From then on, the locking system is triggered by means of comparator (C) activated by resistance (R8), and a high logic level is emitted from output 3 of the same comparator, this being a permanent level, independently of any other logic levels that may eventually be applied to inputs 1 and 2 thereof. In practical terms, SITUATION 2 (shown on the display as a green LED blinking) indicates that the device is in the optimum temperature range, predetermined for preservation of the product to which said device was applied.

SITUATION 3 - Device subjected to temperatures higher than the threshold temperature. When the temperature imposed on thermistor (TM1) is raised to values higher than the threshold temperature, the logic level on input 2 of comparator (A) is low in relation to the reference voltage of input 1 of the same comparator, imposing a low logic level to output 3 thereof, thereby causing the following results in a simultaneous manner: A) In the course of the limit time a) The low logic level of output 3 of comparator (A) is inverted on output 2 of Not gate

(D) and on input 2 of And gate (G). As seen before, on input 1 of And gate (G) there is a permanent high logic level, which causes a high logic level on output 3 thereof and on input 1 of Not gate (K). At the output 2 of the same Not gate (K) the logic level is low, which allows to activate the start of limit time counting by the frequency divider (CI4) and clock (CI5). b) The low logic level of output 3 of comparator (A) is the same as on input 1 of And gate (I), and on input 2 of the same gate there is a pulsing logic level coming from clock (CI6) and a low logic level on output 3 thereof, thereby providing the deactivation of LED (LD2), which stops blinking. c) The high logic level on output 3 of And gate (G) is the same on input 1 of And gate (H), and there is a pulsing logic level on input 2 of the same gate, coming from the clock

(CI6) and a resulting pulsing logic level on output 3. This pulsing logic level on output 3 of And gate (H) is the same pulse of input 1 of And gate (L), on input 2 of which is a high logic level (resulting from SITUATION 2), which remains in this manner during the entire course of the limit time. The high logic level on input 2 and pulsing logic level on input 1 of And gate (L) cause on output 3 of the same gate (only in the course of the limit time) a pulsing logic level, actuating LED (LD3). The condition of blue LED blinking is shown on the display.

Note 1 : It is important to emphasize that in the course of the limit time, SITUATION 2 can be re-established, it sufficing to that effect to decrease the temperature imposed on the thermistor (TM1 ) down to a range of temperatures lower than the threshold temperature.

Note 2: In the case of the event mentioned on note 1 , the frequency divider (CI4) can be zeroed (or not), thereby re-establishing (or not) the original limit time. In practical terms, SITUATION 3 item (A) means that: the blinking of the blue light indicates that the device is at the "improper" temperature range for preservation of the product to which it has been applied and also that the limit time is running out. Thermistor (TM2) causes the frequency of clock (C15) to increase when the ambient temperature is raised, thereby resulting in a shorter limit time for higher temperatures. It can be concluded then that the higher the threshold temperature, the sooner the device will indicate the "improper" storage condition, which will be evidenced on the display, by the red LED blinking. B) upon lapse of the limit time a) Upon lapse of the limit time, the frequency divider (CI4) issues a high logic level on pin 1 1 , the latter being directed to input 2 of comparator (B). Input 2 of said comparator has a high logic level in relation to the reference voltage applied to input 1. The same comparator (B) issues a high logic level on output 3, activating the locking system, by means of resistor (R5); such level is transmitted to input 1 of Not gate (E), wherein, on output 2 of the same gate, after being induced to invert itself, it becomes a low logic level, thereby imposing the same level on input 2 of And gate (L), the input 1 of which is fed by a pulsing logic level, thereby imposing a low logic level on output 3, thereby obtaining as a final result, the turning off of LED (LD3). b) Simultaneously, the high logic level found on output 3 of comparator (B) is imposed on input 1 of And gate (J), wherein, on input 2, is a pulsing logic level coming from the clock (CI6), thereby causing a pulsing logic level on output 3 of the same gate, thereby resulting in the enabling of the LED (LD1), which starts to blink in an irreversible manner, due to the locking caused by resistor (R5). Accordingly, the display is imposed the red LED blinking condition.

In practical terms, SITUATION 3 item (B) indicates on red LED blinking, that the product has been exposed to temperatures above the threshold temperature and also for a time longer than the limit time. It can then be concluded that the product to which the device was applied is in improper storage conditions.

SITUATION 4 - The device is again taken to temperatures lower than the threshold temperature.

When the temperature imposed to thermistor (TM1) is AGAIN reduced to values lower than the threshold temperature, a high logic level is obtained on output 3 of comparator (A), this being the same level on input 1 of And gate (I), the input 2 of which shows a pulsing logic level coming from clock (C16), causing a pulsing logic level on output 3, actuating the LED (LD2) simultaneously with LED (LD1), which was already pulsing in an irreversible manner. The display shows the condition of red and green LEDs blinking. In practical terms, SITUATION 4 may in some cases mean a FRAUD. Note: The blinking times, or on time and off time imposed on the LEDs can be regulated by means of resistors (R16) and (R17) and by the capacitor (C1). Naturally, the details of construction and the manners of realization can be amply varied in relation of the description and illustrations hereon, without departing from the scope of the present invention, as defined by the following claims:

Claims

1. A device for the monitoring of the storage temperature conditions over time of a stored product, said device comprising: a. temperature sensor apparatus for generating a temperature signal which is functionally related to the actual storage temperature; b. first threshold temperature storage apparatus for storing the value of the selected threshold temperature range desired for said product; c. first temperature comparator apparatus for comparing the output of said temperature sensor apparatus and said first threshold temperature storage apparatus for generating a first or second temperature signal indicating that the storage temperature is inside or outside the threshold storage temperature range respectively. d. clock apparatus activated by said second temperature signal for generating a timing signal; e. first temperature-time counter apparatus activated to process said timing signal for accumulating the elapsed times during which the storage temperature is outside the threshold temperature range. f. first threshold time storage apparatus for storing a pre-selected maximum total time during which said product can be exposed to temperatures outside said threshold temperature range; g. first threshold time comparator apparatus for generating a spoilage signal whenever the output of the first temperature-time counter apparatus reflects an accumulated time equal to the pre-selected maximum total time as stored in the threshold time storage apparatus; and h. spoilage indicator apparatus irreversibly activated by said spoilage for indicating possible spoilage of the product.

2. A device, according to claim 1 , further comprising more than one first set of the following apparatus: a. second temperature range storage apparatus for storing a pre-selected temperature range, said pre-selected temperature range being outside the threshold temperature range and being contiguous and not overlapping with the other pre-selected temperature ranges stored in the additional second temperature range storage apparatus; b. second temperature comparator apparatus for generating a temperature range signal whenever the output of the temperature sensor apparatus indicates that the storage temperature is within the temperature range stored in the corresponding and associated second temperature range storage apparatus; c. second threshold time storage apparatus for storing a pre-selected maximum storage time allowed at the corresponding temperature range; d. second temperature-time counter apparatus activated by said corresponding temperature range signal for processing said timing signal to accumulate the total elapsed times during which the storage temperature was within the corresponding temperature range; and e. second threshold time comparator apparatus for generating a spoilage signal for irreversibly activating said spoilage indicator apparatus whenever the elapsed time corresponds to the maximum time stored in the corresponding second threshold time storage apparatus;

Wherein the times stored in each second temperature-time counter apparatus are added by said temperature-time counter apparatus for comparison with the maximum total time stored in said first threshold time storage apparatus for generating a spoilage signal whenever the time accumulated in the first temperature time counter apparatus equal the maximum total time stored in said first threshold time storage apparatus.

3. A device according to claim 2, wherein said first threshold temperature storage apparatus allows the selection of a desired temperature range having both a lower and an upper temperature and wherein said first temperature comparator apparatus generates a first temperature signal whenever the measured storage temperature is within the appropriate temperature range, a second temperature signal when the temperature is above the desired temperature range and a third temperature signal when the temperature is below the desired temperature range and wherein said first set of apparatus, said first temperature-time counter apparatus and said first threshold time storage apparatus process said second temperature signal and further comprising: a. low range clock apparatus activated by said third temperature signal for generating a timing signal when the temperature is below the threshold temperature range; b. more than one second set of the following apparatus: i. third temperature range storage apparatus for storing a preselected temperature range below the threshold temperature range, said pre-selected temperature range being contiguous and not overlapping with the other pre-selected temperature ranges in the additional third temperature range storage apparatus; ii. third temperature comparator apparatus for generating a corresponding low temperature signal whenever the output of the temperature sensor apparatus indicates that the storage is within the temperature range stored in the corresponding third temperature range storage apparatus; iii. third threshold time storage apparatus for storing a pre-selected maximum storage time allowed at the corresponding temperature range; iv. third temperature counter apparatus activated by the corresponding low temperature signal for processing the timing signal generated by said low range clock apparatus to accumulated total elapsed times during which the storage temperature was within the corresponding temperature range; and v. third threshold time comparator apparatus for generating a spoilage signal for irreversibly said spoilage indicator apparatus whenever the elapsed time correspond to the maximum time stored corresponding third threshold time storage apparatus. c. low range temperature-time counter for adding the times stored in all said third temperature counter apparatus; d. low range threshold time storage apparatus for storing a pre-selected maximum allowable storage time at temperature below the threshold temperature range; and e. low range threshold maximum time comparator apparatus for generating a spoilage signal when the total time in the low range temperature-time counter apparatus equals the low range maximum total time.

4. A device, according to claim 2, further comprising counter resetting apparatus for resetting all counter apparatus if the first temperature signal prior to the activation of said spoilage indicator apparatus.

5. A device, according to claim 2, further comprising: a. manual pre-activation apparatus for pre-activating the partial operation of said temperature sensor apparatus, first threshold temperature apparatus, and first temperature comparator apparatus; and b. circuitry activation apparatus for enabling the prospective operation of all other apparatus, said circuitry activation apparatus being irreversibly latched, to enable said prospective operation, by the first occurrence in time of said first temperature signal generated by said first temperature comparator apparatus.

6. A device, according to claim 5, wherein said manual pre-activation apparatus activate an SCR element which irreversibly pre-activates the device.

7. A device, according to claim 5, further comprising: a. proper storage temperature indicator apparatus, said apparatus being activated by the presence of said first temperature signal, for providing an indication that the product is stored within the threshold temperature range; and b. improper storage temperature indicator apparatus, said apparatus being activated by the presence of said second temperature signal, for providing an indication that the product is stored outside the threshold temperature range.

8. A device, according to claim 7, wherein said indicator apparatus are either light emitting devices, or sound emitting devices, or any combination thereof.

9. A device, according to claim 7, wherein the length of each maximum storage time stored in each said second threshold time storage apparatus is generated by a function, said function being suitable for the stored product, of the corresponding pre-selected temperature range.

10. A device, according to claim 9, wherein said length of each maximum storage time decreases as the corresponding pre-selected temperature range is further removed from the threshold temperature range.

11. A device according to claim 10, wherein the second maximum time storage apparatus associated with the pre-selected temperature range farthest away from the threshold temperature range is set for a time value of zero.

12. A device, according to claim 7, further comprising: a. time units counter apparatus for tracking elapsed times, said time units counter apparatus being activated by said manual activation apparatus; b. maximum life storage apparatus for storing the maximum length of time after which the product is considered unsuitable for use; and c. maximum life comparator apparatus for generating a spoilage signal when the elapsed time of the time units counter apparatus equals the time stored in the maximum life storage apparatus.

13. A device, according to claim 12, wherein said time units counter apparatus is activated by the first occurrence of a first temperature signal generated by the first temperature comparator apparatus.

14. A device, according to claim 7, wherein said temperature sensor apparatus is a thermistor.

15. A device, according to claim 7, wherein said temperature sensor apparatus is an electronic thermometer.

16. A device, according to claim 14, wherein said threshold temperature storage apparatus is represented by a voltage selected by varying a variable resistor.

17. A device, according to claim 7, wherein the device is permanently encapsulated in a temperature-resistant material and wherein said device is intended for a single utilization.

18. A device, according to claim 17, wherein the functional operation of all apparatus other than temperature sensor apparatus, indicator apparatus and manual pre- activation apparatus are performed by integrated circuits.

19. A device, according to claim 18 wherein the functional operation of each of said apparatus is performed by integrated circuits.

20. A device, according to claim 17, wherein the functional operation of all apparatus other than temperature sensor apparatus, indicator apparatus and manual pre- activation apparatus are performed by a programmable processor.

21. A method of monitoring the temperature conditions over time of a stored product, including pre-programming a disposable monitoring unit to account for the desired storage temperature characteristics of the product, affixing said monitoring unit to the product prior to storage, and interpreting, during, or at the end of storage, the mutually exclusive outputs of said unit, namely: a. an active first output, indicating that the product is being stored within the preprogrammed acceptable temperature range; b. an active second output and inactive first output, indicating that the storage temperature is outside said acceptable temperature range; c. an irreversibly latched active third output and inactive first and second outputs, indicating that the product was stored at a temperature outside said acceptable temperature range for a length of time at least equal to the pre-programmed maximum acceptable time for storage of the product outside said acceptable temperature range, said active third output further indicating that the product may be unsuitable for use; and active first and third outputs indicating that the product is again being stored, either accidentally or intentionally, within said acceptable temperature range, after the activation of said third output.