FIELD OF THE INVENTION

The present invention relates to methods and devices for indicating, subsequent to an initial action, that the action has occured and for maintaining this indication or gradually varying this indication until lapse of a pre-defined time interval.

BACKGROUND OF THE INVENTION

Many of the daily life activities involves a wish for retrospective inspection of whether or not an activity or action has been performed within the past time elapsed or for indicating the time passed since a particular activity or action. In the art, many mechanical or electronic surveillance provisions have been developed for providing information as to the delay of time since an activity or action and which may be used for retrospective inspection.

BRIEF DESCRIPTION OF THE INVENTION

Having regard to the above-identified prior art, it is an object of the present invention to provide a timer device solution which provides an elapsed time indicator of a less complex construction. A further object is to provide a simple and cost-effective solution so that the time delay indicator will be adaptable for inclusion in various applications.

In a first aspect the present invention relates to a time delay/time lapse indicator being adapted to change responsive to being exerted to pressure and/or force from a first state to a second state and to change to a third state or return to the first state after lapse of a pre- defined time interval subsequent to said application of pressure and/or force.

The time delay indicator according to the first aspect may comprise a pressure sensitive substance exhibiting a change in a state from the first state to the second state when exerted to pressure and/or force and exhibiting a change in a visual property from the second state to a third state upon lapse of said pre-defined time interval. The time delay indicator may or may not exhibit a change in a visual property when changing from the first state to the second state. In case that the time delay indicator exhibits a visual change at the specific point in time where it is exerted to pressure or force and also a visual change from said second state to said first state upon lapse of the pre-defined time interval, the time delay forms a reversible indicator. Some embodiments may include a time indicator which may be re-activated at least once, so that the time delay indicator may be re-used for a plurality of actions. In some embodiments, such re-activatable time indicators may be adapted to re-set the lapse of the pre-defined time interval upon a new activation within lapse of a previously started predefined time interval. In particular embodiments, the pressure sensitive substance is adapted to alter one or more visual properties selected from the group consisting of colour, absorptivity, reflectivity, transmissivity, diffusivity, and polarization when being exerted to a change in pressure and/or force and/or upon lapse of the pre-defined time interval. Within the context of the present invention, additional or alternative optical property changes can be incorporated in the time lapse indicator as well without departing from the scope of the invention.

The pressure sensitive substance may be reversible so that the indicator returns to the initial visual state upon lapse of the pre-defined time interval. Also, the pressure sensitive substance may be re-activatable such that the pressure sensitive substance may be brought into the second state more than once when exerted to repeated activation. Hence, in some embodiments, the pressure sensitive substance may be brought from the first state to the second state more than once or from the third state to the second state more than once. The pressure sensitive substance may be so selected that the pre-defined time interval is initialised by subjecting the pressure sensitive substance to a change in pressure or force, such as upon exertion of pressure/force or upon release of said pressure/force. In some embodiments, the pressure sensitive substance is selected so that the time lapse indicator, when being brought into the second state, by renewed action such as by a further actuation of an actuator, prolongs the time interval a duration of time equal to the pre-defined time interval.

The pressure sensitive substance may be so chosen as to substantially exhibit a uniform visual appearance throughout the course of the pre-defined time interval so that a particular marked change in the visual appearance upon lapse of the pre-defined time interval is obtained.

The time lapse indicator of the present invention may be designed so that the pre-defined time interval is longer than 5 minutes, such as longer than 15 minutes, such as longer than 30 minutes, such as longer than 1 hour, such as longer than 2 hours, such as longer than 5 hours, such as longer than 10 hours.

In some embodiments, the time lapse indicator is positioned next to a permanent indicator for comparison of the visual appearance of the time lapse indicator with one or more reference fields. The pressure sensitive substance may comprise a piezochromic material. Said piezochromic material may be reversible so that the indicator returns to the initial visual state upon lapse of the pre-defined time interval. Also, said piezo-chromic material may be re-activatable.

In some embodiments, the time lapse indicator may exhibit more than a single time expiry indication by incorporating a plurality of pressure sensitive substance portions each having a different lapse time for exhibiting the visual change at lapse of each individual time interval. The plurality of pressure sensitive substance portions may be formed as separate segments, i.e. areas of sufficient size to visually provide a distinct indication of each of the lapse times of the individual segments. In other embodiments, the plurality of pressure sensitive substance portions may be formed as intermeshed pixels. Such embodiments may be formed to provide multiple changes in a visual property, such as by changing from a first to a second colour upon lapse of the first time interval and change from the second to a third colour upon lapse of a second time interval and optionally even more colour changes upon lapse of particular further time intervals.

A non exhaustive list of usable materials includes bianthrones, spiropyrans, salicylidene anilines, fluoran compounds, metal cluster compounds and copper complexes. A reversible indicator may comprise a piezochromic system comprising an electron donating compound and an electron accepting compound. The electron donating compound is an ionochromic substance which is a pH-sensitive dye and the electron accepting compound acts as the colour developer. The developer has acidity strong enough to change the colour of the ionochromic substance by protonation, yet weak enough to allow the system to remain reversible. Suitable ionochromic compounds are electron donating compounds such as pH- sensitive dyes, preferably leuco-dyes, or other colour formers. Most commonly used often belong to the spirolactone class. The protonation of a colourless or substantially colourless lactone by a weak-acid developer causes the lactone ring to open and results in a formation of a coloured compound.

The piezochromic materials may further be selected as one or more of the materials disclosed in US patent application No. 2007/0259286, in particular the materials mentioned in Table 3 of this reference, this reference being incorporated herein in its entirety.

In other embodiments, the pressure sensitive substance is selected as one or more of the materials disclosed in US 2007/0172951 , US 4,687,862, US 6,261 ,469, US 5,320,784 and US 5,501 ,945.

Any of the features mentioned above in connection with the first aspect may combine with any of the features of the following additional aspect of the invention (aspect 2 to 13).

In a second aspect the present invention relates to a blister package having one or more blister cavities for accommodating or accommodating an article or a portion of bulk or fluid material in each of said one or more blister cavities, each of said one or more blister cavities comprising:

- a first material portion defining at least one cavity, and

- a lid portion closing off said at least one cavity, wherein said blister package comprises a time delay indicator as defined in said first aspect.

In a first embodiment said time delay indicator is associated with at least one of said blister cavities so that the time delay indicator is activated upon a user gaining access to the article or portion of bulk or fluid material in said cavity. Such indicator may be pressed or squeezed by the user upon dispensing from each of said blister cavities, either by the dispensing activity or by an action separate from said dispensing activity.

In another embodiment, the blister package comprises a plurality of blister cavities where each of the blister cavities is associated with a respective time delay indicator. In a further embodiment, the blister package comprises a plurality of blister cavities but a single time delay indicator which is adapted to be re-activated such that it may be activated more than once to change from said first state to said second state. In such embodiments, the time delay indicator is manually activated upon the dispensing from each of the blister cavities.

The lid of said blister package may be formed as a planar sheet, or alternatively define a second cavity positioned to mate with the corresponding cavity/cavities formed in the first material portion, the cavity/cavities of the lid either facing or facing away from the cavity/cavities of the first material portion. In some embodiments, the first material portion and the lid may be formed as contiguous sheets of materials that are bonded together or, alternatively, the first material portion and the lid may be formed by the same sheet of material which is folded along an edge and then bonded. In embodiments where the blister package forms a plurality of blister cavities, the first sheet portion or, alternatively, the lid may be formed as individual portions which are mutually spaced relatively to each other. The time delay indicator(s) of the blister package may be associated with the first material portion and/or the lid, e.g. formed on or in the sheet materials of the first material portion or the lid. One or both of the sheet materials may be formed of a material which itself exhibits a visual change during or after lapse of time after the material has been exerted to pressure and/or force, e.g. when a particular blister cavity is manipulated for dispensing the contents of the blister cavity. In this way the particular time delay indicator in question is activated when the associated blister cavity is accessed, e.g. when one of the layers associated with a blister cavity is ruptured.

By incorporating a time lapse or delay indicator of the above kind into a blister package according to the second aspect, a user may easily check whether the blister package has been used for dispensing within the preceding pre-defined time interval.

For example, when the blister package holds one or more medicament articles or holds one or more portions of bulk or liquid medications, the time indicator may be used by a patient to ensure whether or not a dispensing has been performed within an elapsed time interval corresponding to the preceding pre-defined time interval. Hence, if the user does not feel confident as to whether he or she is in proper compliance with the personal treatment plan, the time indicator may be used to improve confidence and ultimately be used for a proper corrective action if needed. The above solution forms a simple and reliable indicator enabling an easy incorporation into a medical blister package. Furthermore, when being built into the blister package as an integral part, a particularly user-friendly solution is provided which do not require any user involvement in the operation of the timer indicating function. In a third aspect, the present invention relates to a tool for dispensing single items or portions from a blister package such as the tool shown in WO 2007/058586, wherein the tool comprises a time lapse indicator as defined in the first aspect, the time lapse indicator being adapted to change from the first to the second state upon operating the tool for dispensing an item from the blister package. Further fourth through thirteenth aspects of the invention are described below.

In the context of the present invention, the term "pressure sensitive substance" shall be understood as any substance or composition which exhibits a change in a visual property when exerted to pressure and/or force. The term "pressure sensitive substance" encompasses both a single substance or material which exhibits the above change in a visual property when exerted to pressure and/or force as well as a combination of substances which interacts under the influence of pressure and/or force to exhibit a change in a visual property.

DETAI LED DESCRIPTION OF THE INVENTION The invention will now be described in further detail with reference to the drawings in which:

Fig. 1 shows a prior blister package according to the second aspect of the invention,

Fig. 2-41 shows further embodiments of time delay indicators of various aspects of the invention.

Fig. 1 shows an exemplary embodiment blister package 100 according to the second aspect of the present invention. The blister package includes a first material portion which forms a first layer defining a plurality of cavities and a lid layer, the two layers being bonded to each other at peripheral portions of each cavity to thereby form a plurality of separate compartments. Each compartment sealingly accommodates a medicament pill or tablet 101. When a user presses onto one of the compartments, the pill or tablet contained therein is dispensed from the blister package (as seen in the upper drawing of fig. 1 ).

A time delay indicator including a reversible piezochromic material is associated with each respective compartment so that upon rupturing the lid portion in question, the time delay indicator associated with that particular compartment changes from a first state to a second state. This state change may be associated with a change in a visual property such as colour or opacity. Due to the controlled reversal time of the piezochromic material, the piezochromic substance remains in the second visual state during a pre-defined time- interval subsequent to the action of dispensing the pill or tablet from the compartment. Upon expiry of the pre-defined time-interval, the piezochromic material returns to the first visual state.

As seen in the middle drawing of fig. 1 , the first material portion forming the cavities includes a piezo-chromic material. It follows from the colour markings of the compartments 102, 103 and 104 that the compartment 104 has been accessed within the preceding pre-defined time interval, whereas the compartments 102 and 103 have been accessed prior to said predefined time interval. It is readily acknowledged that the remaining compartments not yet have been accessed. The colour state of compartment 104 indicates that an administration has been performed within the preceding pre-defined time interval and that further administrations should be postponed at least until the colour indicator associated with compartment 104 returns to its initial state. In this way a potentially harmful double medication can be prevented.

The lower drawing of fig. 1 shows a further embodiment of a blister package. However in this embodiment the time delay indicators comprising the piezo-chromic material are associated with the lid layer that is adapted to rupture upon dispensing pills or tablets from the blister package.

The piezo-chromic material may be selected so that the reversal time of the time delay indicators matches the administration scheme of the particular medication in question. Non- limiting exemplary reversal times may be selected such as 10 minutes, 30 minutes, 1 hour, 3 hours, 6 hours, 12 hours or 24 hours. Other reversal times may also be chosen. In fig. 2, a pill receptacle according to the fourth aspect of the invention is shown. The pill receptacle has a closure portion including a time delay indicator. Upon manipulating the closure portion, i.e. when one or more pills are removed from the receptacle the time delay indicator changes visual appearance from a first state to a second state. After lapse of a pre- defined time interval the visual state of the time delay indicator returns to the first visual state.

In fig. 3, two embodiments of receptacles according to the fifth aspect of the invention are shown, each receptacle having a sealed closure including a time delay indicator. The embodiment to the left shows a milk carton erected from a blank. The milk carton has an initially sealed closure portion including a time delay indicator. The time delay indicator provides a change in a visual property upon expiry of a predefined time period, said predefined time period being initiated upon breaking the seal, i.e. at first access to the liquid contained in the carton. By selecting the material included in the time delay indicator so that the pre-defined time period is say 48 hours, the time delay indicator can be used for indicating whether the liquid contained in the carton is freshly opened or not. The time delay indicator may include a reversible piezo-chromic material, so that the time delay indicator changes from a first visual state to a second state when the seal is broken and returns to the first visual state upon lapse of the time delay indicator. The embodiment shown to the right is a bottle having an initially sealed closure including a time delay indicator where the time delay indicator is automatically activated upon initial opening of the sealed closure.

Fig. 4 shows a flexible receptacle or bag according to the sixth aspect of the invention, wherein a time delay indicator is associated with either a rib-and-groove type closure or a zipper-like closure at the opening portion of the bag. The time delay indicator may be of the same type as described in connection with the fifth aspect. Fig. 5 shows a flexible foil according to the seventh aspect of the invention, which includes at least one time delay indicator arranged on or formed integral with the foil. The foil is shown to be wrapped around a piece of food, such as a burger. The time delay indicator exhibits a change in a visual property when manipulated to wrap the burger. Upon expiry of a pre-defined time interval, the time delay indicator further exhibits a change in a visual property. Hence, the time delay indicator may be used for indicating the freshness of the burger. Fig. 6 shows a time indicator according to the eight aspect of the invention. A closure incorporating a peel-off foil is adhered to an article by means of an adhesive which include a time delay indicator including a piezochromic material. Upon removal of the peel-off foil the time delay indicator is initiated. Fig. 7 shows a further example of a receptacle having a time delay indicator including a reversible and re-activatable piezochromic material arranged on a closure release button, said closure release button being arranged to flex inwards upon pressing on the button. Due to the flexure of the button, as shown in fig. 8, the piezochromic material exhibits an effective change of state in a visual property. Fig. 9 shows a similar construction of a receptacle having a hinged lid. The time delay indicator in this example is associated with one or more of the hinges. In a particular embodiment, the receptacle takes form of a suitcase, whereby the time delay indicator can be used to reveal that the suitcase has been opened within the preceding pre-defined time interval, thereby indicating a possible unauthorized access to the suitcase. A similar warning may be provided in association with an entrance to a room or house by associating a time delay indicator to a handle of a door or alternatively to the hinges of the door. Fig. 10 shows an alternative embodiment of a food receptacle with a time delay indicator positioned on a lid of the receptacle, said time delay indicator being activatable by rubbing the time delay indicator mechanically. The time delay indicator may be used for indicating time expiry since initial packaging of food in the receptacle. Fig. 1 1 shows a cigarette case having a time delay indicator associated with the closure of the cigarette case. The time delay indicator may include a reversible and re-activatable piezochromic material which may indicate that a cigarette has been removed from the cigarette case within the preceding predefined time interval.

Fig. 12 shows a mail box having a reversible and re-activatable time delay indicator associated with a closure of the mail box. The indicator may be used to indicate that mail has been delivered so that the owner of the mail box does not have to check the mail box by physical inspection.

Fig. 13, 14 and 15 show examples of various sporting goods according to a ninth aspect of the invention, more particularly a tennis ratchet, a football shoe and a golf club respectively. Each of those items are provided with an extended surface portion upon which is disposed a relatively large area with a reversible and re-activatable time delay indicator comprising a piezochromic material. The time delay indicator exhibits for a pre-defined duration a colour change at a point of impact. When subsequently inspecting the point of impact, this information may be used for improving the technical skills of the individual using the sporting goods in question. Fig. 16, 17 and 18 show examples of various time delay indicators associated with lines and specific areas on or in sporting fields. Fig. 16 and 17 depicts a tennis court, where the various lines on the ground and/or the various areas next to the lines are provided with a reversible and re-activatable piezochromic material time delay indicator which provides a colour reversal time such as in the order of 5 to 30 seconds. By using such time delay indicators, the points of impact of a tennis ball may be inspected retrospectively without requiring the use of video recordings. Similarly, fig. 18 shows a time delay indicator associated with the crossing line used in long jump sites, where the crossing of the line by an athlete may be retrospectively inspected. Similar arrangements may be used in connection with other sport games, non-limiting examples being football or soccer, squash and volleyball. Fig. 19 show a dance mat or dance floor covering, where a similar piezochromic material is applied on the area intended for dancing and the steps may thus be retrospectively checked. Similar provisions may be used in areas which should be surveilled with respect to unauthorized access. Individuals accessing said areas will reveal themselves within the pre-defined time interval of the time delay indicator if they step upon the area under surveillance. Again, a similar time delay indicator may be used for checking whether a surface area has been properly cleaned, the indicator being activated when being rubbed due to cleaning.

Fig. 20 show examples of a time delay indicator which is provided on a chair or a seat within areas of public access, such as in bars or in public transportation. A colour indicator may be used for identifying whether a particular seat is occupied or not, even if an occupant has left the chair or seat only for a short while. Appropriate colour reversal times may be in the order of say 30 seconds or a few minutes.

Fig. 21 show an example of a lipstick having a reversible and re-activatable time delay indicator applied onto a surface of the handle portion or onto a cap surface of the lipstick. A user may choose to re-apply lipstick when the time delay indicator no longer shows trace of a previous use. In accordance with the tenth aspect of the invention, fig. 22a shows a key for locking and unlocking a lock such as a lock for a door. The key is at a surface portion thereof provided with a reversible and re-activatable time delay indicator which reveals that the key has been in use during a past pre-defined time interval. Exemplary time reversal durations may be chosen within say 1 minute to a couple of hours. Every now and then, most individuals, after leaving a property, are in doubt as to whether or not a door lock has been properly locked. After using the key for locking the lock, the time delay indicator indicates key usage within the past pre-defined time interval, on the affirmative providing comfort to the individual. Naturally, a corrective action may be performed if it shows that the key has not been in use in a situation where it should have been in use. In the depicted embodiment, the time delay indicator comprising a piezo-chromic material is applied to the gripping portion of the key. Alternatively, or in addition, the piezo-chromic material may be applied to the keyed projections/depressions which cooperate with co-working elements in the door lock.

In fig. 22b an electronic key is shown which includes one or more buttons for remotely (wirelessly) locking and/or unlocking a lock, such as a locking mechanism of a vehicle door and wherein a time delay or time lapse indicator is associated with one or more of the buttons of the electronic key. The shown electronic key includes a separate button for unlocking the door and a separate button for locking the door. In the shown embodiment, one of the buttons, such as the lock button, is associated with a time delay indicator so as to provide an indication whether or not the user of the key has used the key for locking the door of the vehicle within the past pre-defined time interval. The time lapse indicator may be arranged on top of the button, be incorporated into the button or may alternatively surround the button. The time lapse indicator and its associated button may be so configured that the operation of the button causes the time lapse indicator to be activated and to be re-activated upon further operation. In the drawing, the electronic key is provided with a mechanical key for mechanically engaging and operating an associated lock. However, such mechanical key may be omitted from the electronic key. As such, the electronic key may take other forms, such as key cards having a shape as a credit card.

Fig. 23 shows a first embodiment of a tool according to the eleventh aspect of the invention. The shown tool is a wrench tool having a tapered portion which is adapted to flex to a calibrated degree in accordance with an applied force or momentum exerted on the tool. The flexible portion is provided with a time delay indicator applied along the flexible tapered portion so as to provide a scale. The amount of force or momentum exerted on the tool can be momentarily read on the scale. Due to a controlled reversal time of the time delay indicator a peak force or momentum may be read on the scale for a pre-defined time interval after stresses have been relieved from the tool. In a particular simple embodiment, the time delay indicator is able to show that a force or momentum above a certain threshold has been applied, and can be inspected retrospectively.

Second and third embodiments of a tool in accordance with the eleventh aspect are shown in fig. 25. In fig. 25 two embodiments show respective versions of weighing devices. Each of those tools works in the same way as in the wrench tool described above, i.e. a time delay indicator is applied to a portion of the device which is able to flex when under strain. Also fastening elements which includes a piezo-chromic material that indicates a preferred fastening momentum may be envisioned according to the present invention. Fig. 24 shows a lock washer including a piezo-chromic indicator for use with a fastening element such as a bolt. The lock washer is a taper washer which has a substantially conical configuration in the unstressed state. However, as the fastening element is tightened the locking shim becomes substantially planar. The piezo-chromic indicator is adapted to change colour when an appropriate fastening momentum is applied. The lock washer is a non-limiting example of a fastening element having a piezo-chromic stress indicator with or without a memory function.

Fig. 26 shows a device for counting elapsed time and including a piezo-chromic material arranged on a deformable elastic member. The elastic member may be prolonged by pulling the ends of the device apart. The device is so configured as to enable the elastic member to slowly return to its initial configuration. The piezo-chromic material is formed along a scale and the elastic member is tapered along its length so as to provide a substantially linear time scale. The device may be used as a count down timer.

Fig. 27 shows a cork screw having a time delay indicator disposed thereon so as to provide an indication that sufficient time has passed since using the cork screw. The time delay indicator may be associated with a handle, associated with a flexible portion which changes shape during operation or associated with the helical portion of the tool.

Fig. 28 shows an embodiment of an appliance with a temperature sensitive indicator comprising a piezo-chromic material. The shown figure depicts a pot for holding a liquid, the pot having a piezo-chromic based colour indicator applied thereon to indicate a proper or improper temperature of the liquid within the pot. The colour indicator is formed on top of a bimetal spring which is adapted to change shape when subject to a change in temperature. The piezo-chromic material is adapted to change colour in accordance with a predefined temperature. The liquid pot is a non-limiting example of a temperature sensitive indicator involving a piezo-chromic material.

Fig 29 shows a bandage and a bandage dressing having a piezochromic indicator formed on or in the bandage to indicate if the bandage is wound too tight when applied to a patient or for indicating that a bending actually does happen. Fig. 30 show a balloon with a piezochromic indicator formed on or in the balloon material so that the balloon changes from one colour to a different colour as the balloon is inflated. Fig. 30 shows a pair of glasses where the lense-surface incorporates a time delay indicator being of the reversible kind. In order to ensure a uniform cleaning of the lenses, the lenses changes colour when the lens surface is rubbed with a cloth for cleaning. An appropriate colour reversal time would be in the order of seconds, such as 5 or 10 seconds. Fig. 32 shows a booklet or other printed matter where a reversible time delay indicator is applied to one or more fields, optionally as printed matter such as characters or numbers. In one form, the printed matter includes a multiple choice test where the correct answer is initially concealed. When rubbing on possible answer fields, the correct field will reveal itself for a pre-defined time. Also, a single answer may be printed in a way that it is initially invisible to the human eye but reveals itself for a pre-defined time when being rubbed by a finger or the like. After lapse of the pre-defined time interval, the printed matter returns to the initial state enabling the test to be repeated by other people. Fig. 33 shows a ticket or the like for authentication purposes which is printed with an indicia incorporating a reversible piezo-chromic material. After lapse of a pre-determined time-interval the indicia will change to a different visual appearance indicating lapse of the validity of the ticket. Furthermore, the ticket may include a machine-readable code such as a bar code or matrix code where said code comprises a piezo-chromic material having a pre-defined reversal time.

Fig 34 shows a card-game having one or more numbers of cards each having one ore more questions and one or more answers which relates to the question(s) printed thereon. Either the question(s) or the answer(s) is printed with a reversible time delay indicator such as a piezo-chromic material so adapted as to become invisible to the human eye for a predetermined time interval after being activated by mechanical energy. The card-game may include a pair of rollers to provide the mechanical energy to thereby make the time delay indicating indicia disappear for a pre-defined time interval. Upon lapse of a pre-defined time interval, the question(s) or answer(s) reveal themselves.

In accordance with the twelfth aspect of the invention, figs. 35 to 39 shows different examples of time delay indicators involving more than a single time expiry indication by incorporating a plurality of piezo-chromic material portions each having a different reversal time.

Fig 35 shows such time delay indicator having a plurality of closely intermeshing dots of respective first and second types of piezo-chromic material. By initially rubbing the surface of the time delay indicator, both types of piezo-chromic materials are activated to change appearance to a respective second state. After expiry of a first pre-defined time interval, the first piezo-chromic material returns to its initial state, whereas the second piezo-chromic material returns to its initial state somewhat later after expiration of a second time interval. By appropriately choosing the visual state changes of each of the piezo-chromic materials, the time indicator may visually indicate three different states, e.g. a first colour prior to activation, a second colour when the time delay indicator is activated and a third colour when the first time interval has expired. The time delay indicator returns to the initial colour after expiration of the second time interval has expired. Further piezo-chromic materials may be incorporated by intermeshing with the other piezo-chromic materials to thereby obtain further state changes. A schematic representation of this effect is shown in the upper row of fig. 38.

A second embodiment in accordance with the twelfth aspect of the present invention incorporates a plurality of time delay indicators arranged as a plurality of segments. The lower row of fig. 38 shows such indicators arranged as four individual segments arranged as four annular segments of a circle. Each individual segment comprises a piezo-chromic material having a distinct state reversal time as compared to the others. The different time delay intervals may be chosen in accordance with the particular application in question. By appropriately choosing the piezo-chromic materials, the approximate time elapsed between each segment state change may be chosen as 30 minutes intervals, hour intervals, 2-hour intervals, 3-hour intervals, 4-hour intervals, 6-hour intervals or twelve hour intervals, said time intervals providing non-limiting examples of the invention. In these examples, the particular group of segments provide a linear scale of the time elapsed since activation. However, also non-linear scales may be provided having non-uniform expiry steps. Alternatively to the circular/anular representation shown in fig. 38 lower row, a concentric type representation may be used, e.g. a central segment and one or more additional ring shaped segments arranged concentrically with respect to the central segment. Also linear scales may be chosen or any other shape.

Also, the principle set forth in fig. 35 and the upper part of fig. 38 may be employed in one or more segments of a segmentized time delay indicator. It should be noted that the two embodiments of fig. 38 only shows the possible different states of the respective scale-type time delay indicators. Embodiments may include scale-type time delay indicators which do not return to its initial state as well as scale-type time delay indicators which do return to its initial state. The latter type mentioned may be of the re-activatable kind which enables repetitive use.

Fig. 36 show an application of where two different messages appear superposed, i.e. overlapping in space, such that the first message is shown prior to activation of the time delay indicator and the second message appear directly after activation almost simultaneously as the first message disappears. Alternatively, the said change happens after expiry of a pre-defined time interval. Still alternatively, the first message disappears at activation of the time delay indicator whereas the second message appears after lapse of the pre-defined time interval. These message-type indicators may be provided by having intermeshed portions of different piezo-chromic materials as explained above in connection with fig. 35.

Fig. 37 shows a pill receptacle of the kind shown in fig. 2 but where the time delay indicator incorporates a scale-type time delay indicator as described in connection with fig. 38 lower row. Fig. 39 depicts a different embodiment showing a parking meter or ticket having a time delay indicator of the above described kind associated therewith. The time delay indicator may have more than two states. For example, the time delay indicator may be of the pixel-type (intermeshing dots), the layered type or the segmentized type.

In accordance with a thirteenth aspect of the invention, figs. 40 and 41 show two embodiments enabling a distinct activation of the various types of time delay indicators described herein. In fig. 40 the pressure or force sensitive visual indicator is either embedded in or arranged onto a sponge like material, whereas the fig. 41 embodiment involves an elastic material such as a gel with the pressure or force sensitive visual indicator embedded or arranged onto the gel. As shear forces or movements are particular effective for activating various types of pressure or force sensitive visual indicators the inherent elasticity of the sponge or gel type embodiments ensures uniform exertion of forces onto a larger surface area of the visual indicator.

Any visual state change property may be used in the above examples. Non-limiting examples includes colour, reflectivity, transmissivity, diffusivity or polarization. As an example, a multi-layered time delay indicator may be provided having a first piezo-chromic material providing a reversible colour change in a first layer and with a second piezo-chromic material being somewhat transmissive in its different states arranged on top of the first layer. If the second (upper) piezo-chromic material has a longer reversal time than the first piezo- chromic material, said time delay indicator may be able to show 3 different states which visually appear as three distinct colours. Alternatively, the upper layer material may comprise a material which changes from opaque to transparent when activated and which returns to the opaque state after lapse of the reversal time of the upper layer material.

It should be noted that although most of the above described embodiments disclose piezo- chromic based time delay indicators, similar embodiments may be provided having other materials or combinations of materials which provide a change in a visual property when exerted to pressure and/or force, these embodiments being likewise within the scope of the present invention.