Abstract:
For use in dispensing a material that has a limited period of utility, a novel device comprises a first part ( 1 ) containing the material and a second part ( 2 ), wherein the first and second parts have mutual engagement means ( 6,7 ) and can be disengaged to allow the material to be dispensed, wherein the device includes, located within the device, control means that can be activated to initiate a time-controlled period of use and that, at the end of that period, causes the first and second parts to be permanently engaged.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to the packaging of non-durable products such as cosmetics, skin care products, sun care products, toiletries, foodstuffs, beverages and certain pharmaceutical products and other non-durable products, principally in containers with reusable closures, the quality and efficaciousness of which deteriorate with respect to time and or exposure to excessive temperature, humidity, light and air and or to the presence of microbes from the point of manufacture or from the first occasion at which the package is opened by the end user. 
       BACKGROUND OF THE INVENTION 
       [0002]    The quality and efficaciousness and in some instances safety of non-durable products deteriorate over time, requiring the packaging within which they are contained to display a “Use By”, “Best Before”, “Expiration” or other date to indicate when the product will become unsuitable for use. Many products deteriorate at an accelerated rate once the packaging within which they are contained has been opened, the causes of which can be physico-chemical degradation due to time, exposure to excessive temperature, humidity, light and air and or microbial contamination. When the deterioration of a product after its opening could cause harm to the consumer, for example the degradation of the U.V. protection of a sun care product or the potential for microbial contamination of a mascara product, the period of time that the product will remain safe to use after opening or “Period after Opening” is often displayed on the product package. However, consumers frequently overlook or disregard the “Use By” or “Period after Opening” information provided, or fail to remember when a product package was first opened, with sometimes deleterious effects to product quality, health and safety. 
         [0003]    With increasing consumer demand for non-durable products with improved quality, safety and lower preservative content, several improvements to the packaging for non-durable products have been suggested. GB2387941 describes a closure for preventing the opening of a bottle after an expiry date and consists of a conventional cap with an internal thread which mates with a threaded sleeve situated within a recess about the neck of a bottle. The sleeve is prevented from rotating about the neck of the bottle by lugs, manufactured from a bio-degradable plastics material, formed on the sleeve and located within indents formed on the neck of the bottle so that the torque required to remove or secure the cap to the bottle is transferred to the lugs. Once the plastic has degraded to a sufficient extent, the force required to remove the cap causes the lugs to shear, thus enabling the sleeve to rotate with the cap about the neck of the bottle, thereby preventing its removal. However, due to the imprecise nature of predicting when the bio-degradable material will degrade sufficiently for the lugs to shear, especially when exposed to changing conditions of temperature and humidity, it is difficult to ensure that the removal of the cap will be prevented within an acceptable time tolerance, thereby rendering the device impracticable for use in most product applications. 
         [0004]    FR2887646 describes a time-indicating unit incorporated into the packaging for a fluid product-dispensing device, to provide a visual indication of elapsed time, to reduce the risk to a consumer caused by using a device containing expired product. The time-indicating unit is automatically activated by means of a push button upon first use of the product, but suffers the disadvantage that the user is relied upon to correctly interpret and act in accordance with the indication provided. 
         [0005]    A number of time-temperature indicators have become available. Timestrip®, produced by Timestrip Plc (UK), for example, is a label-type device which relies on the migration of a tinted liquid through a micro-porous material at a rate dependant on temperature to provide an indication of time elapsed and is designed to monitor the shelf life of a wide range of opened or un-opened products to provide the consumer with a visual indication of when a product has reached the end of its useful life but suffers the disadvantage that the user is relied upon not only to activate and attach the device to the product package but also to correctly interpret and act in accordance with the indication provided. Fresh-Check® produced by the Temptime Corporation (USA), and MonitorMark™, produced by the 3M Corporation (USA), are label type time-temperature indicating devices designed to be affixed to or placed within the packaging for non-durable products and rely, respectively, upon the gradual darkening of a chemical indicator and the migration, at a rate dependant upon time and temperature, of a coloured indicator along a wicking material to provide the end user with a visual indication of when a product has reached the end of its useful life but, once again, suffer the disadvantage that the user is relied upon to correctly interpret and act in accordance with the indication provided. 
         [0006]    To ensure product quality and efficacy and to safeguard the health and safety of consumers, a need therefore exists to prevent the use of non-durable products once the useful life of the product has been exceeded. 
       SUMMARY OF THE INVENTION 
       [0007]    As will become apparent from the following description, and as expressed in the claims, there are at least 3 aspects of the present invention. In one aspect, this invention prevents disengagement of a two-part device after a predetermined time, so that dispensing of a material from one of the parts is prevented. In a second aspect, in consequence of a mechanism beyond the user&#39;s control, the device provides a display at the end of that period, to warn the user. In a third aspect, by similar means, tampering with the device is evident. 
         [0008]    According to the present invention, a time or time-and-storage-conditions-dependant locking system for a product package incorporates, as desired, an indicator to provide the user with feedback as to the state of the locking system and to provide evidence that the package has been opened, the indicator aspect of the invention, whether time or time and storage conditions dependant or provided solely to indicate that a package has been opened, being applicable to the design of a product package independently of the product package locking system, comprising a first part containing a material to be dispensed or utilised, the material having a predetermined acceptable period of utility subject, or not, to its conditions of storage and or usage, and a second part which engages the first part and can be disengaged or displaced to allow the material to be dispensed or utilised through an aperture in the first part, and characterised by a means within the device composed of a locking means acting in unison with a measurement means, whereby, when the predetermined period of utility has elapsed, the first and second part cannot be disengaged or displaced and incorporating as desired a visual indication of the state of the means within the device. 
         [0009]    A particular advantage of the present invention is that rather than relying on the end user to correctly identify, remember and act in accordance with the “Use By” or “Period after Opening” information displayed on a product package, or interpret, act in accordance with and in some cases activate an indicating device that may be attached to a product package, the locking system of the invention physically prevents the product from being dispensed from or utilised within the package after a predetermined period, subject, or not, to the storage conditions of the package, has elapsed. 
         [0010]    The present invention utilises control means which can be activated, to initiate a time-controlled period of use, and which prevents disengagement after that period. Initiation can be at any suitable time, e.g. on first opening, and is not under the user&#39;s control. 
         [0011]    A further advantage of the invention is that, when used to prevent the use of a product once its period after opening has expired, the indicator of the device may be so arranged as to provide, upon the first opening of the package, an indication that the period after opening has commenced and thus, with particular significance to the display and storage of products in a retail setting, provides evidence that the package has been opened, or “tamper evidence”. 
       DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0012]    The first part of the invention may take any suitable form such as a container for a liquid or dry substance or other consumable product such as a water filter for example. Examples of materials that may be contained within the first part will be well known to those of ordinary skill in the art. They include cosmetics and colour cosmetics, e.g. mascara, eye pencils, eye liner, eye shadow, foundation, concealer, blusher, lip liner, lip gloss and lipstick, skin care products e.g. moisturising products, body oil, toners, make-up remover and depilatories, sun care products, e.g. sunscreen and self-tanning lotion, eye care products e.g. eye wash, eye drops and contact lens solution, pharmaceutical and medical products, e.g. vaccines, insulin, ear drops, ointments and cough and cold syrups and foodstuffs etc. The material may be in a single piece or discrete pieces. Depending on the nature of the material, means may be provided for its advancement through an aperture in the first part, whereby the user gains ready access to a further supply of the material or an applicator or other means may be provided to enable the material to be accessed and or applied or used by the user. 
         [0013]    The second part of a device of the invention may take any suitable form such as a screw cap, hinged lid, valve or other reusable closure for a container. Preferably, the second part is provided with a means, such as a ratchet in the case of a screw cap or hinged lid, to enable the second part to be re-engaged or replaced should the first and second parts be disengaged or displaced when the predetermined period elapses. 
         [0014]    The measurement means within the device may be of any nature suitable for the measurement of time or time and storage conditions, including temperature, humidity, light, air and or microbial contamination. 
         [0015]    The measurement means within the device may be of an electrical-electronic nature such as a battery-operated electronic timer circuit so configured as to operate a shape-memory-alloy actuator, solenoid or other electrical-mechanical device at a predetermined time after the device has been activated, the electronic timer circuit including, or not, a monitoring capability for one or more storage conditions. 
         [0016]    Alternatively, the measurement means within the device may be of a mechanical nature such as a spring-loaded piston and cylinder arrangement closed by a gas-permeable barrier, the spring so configured as to generate a positive pressure or partial vacuum within the cylinder, the gas pressure within the cylinder increasing or decreasing, depending on the configuration, with respect to the volume of gas transmitted by the gas-permeable barrier over time. The gas transmission rate of the gas-permeable barrier may be a function of its material or materials of construction, method of manufacture, thickness, area, temperature, humidity and the pressure differential across the barrier. Transmission results in either a relative movement of the piston with respect to the cylinder over time, or the displacement of the piston relative to the cylinder at a specific pressure differential, relative to temperature, humidity and external gas pressure. In an alternative spring-loaded piston and cylinder arrangement, the piston is not sealed to the bore of the cylinder and is so configured as to be capable of moving through a viscous fluid contained within the cylinder at a controlled rate, thereby resulting in a relative movement of the piston with respect to the cylinder over time, the viscosity of the fluid and hence the rate at which the piston is able to move through the viscous fluid being a function of temperature. 
         [0017]    The locking means may be of any form suitable for preventing the disengagement or displacement of the first part relative to the second part, such as a movable element so configured as to prevent or enable, in concord with the state of the measurement means, the relative rotation of a first annular piece about a second annular piece, or a moveable element so configured as to prevent or enable, in concord with the state of the measurement means, the linear movement of a first piece with respect to a second piece. 
         [0018]    Alternatively, the locking means may be so configured as to provide evidence that the package has been opened only. 
         [0019]    The indicator of the device may be so arranged as to provide the user with feedback as to the state of the means before activation, upon activation and once the “use by” or “period after opening” has expired or may be so arranged as to provide, upon activation, a progressive indication of the time elapsed since activation or the time remaining before the “use by” or “period after opening” has expired. 
         [0020]    Alternatively, the indicator of the device may be so arranged as to provide evidence that the package has been opened only, in concord with the suitable locking means. 
         [0021]    Typically, a display of information in a device of the invention will be of different states, indicating one or more of: manufacture, packaging, initiation of the period of use, the period of utility, and the end of that period, i.e. that the device should no longer be used. For example, means within the second part may be provided, giving a display through a window or aperture in the outer wall of the second part. 
         [0022]    Optionally, an audible or visual means acting in accordance with the state of the measurement means of the device may be included with or independently of the indicator of the device to signify to the user that the expiration of the “use by” or “period after opening” is approaching. Suitable audible means include a piezo sounder or other audible device acting in unison with the electronic timer and so configured as to play a recorded message or emit a tone or sequence of tones at regular intervals for a predetermined period before the “use by” or “period after opening” expires. Suitable visual means include a light-emitting diode or other light-emitting device acting in unison with the electronic timer and so configured as to flash at regular intervals for a predetermined period before the “use by” or “period after opening” expires. 
         [0023]    Also optionally, an audible or visual means acting in accordance with the state of the measurement means of the device may be included with or independently of the indicator of the device to signify to the user, upon initiation, that the “period after opening” has begun. Suitable audible means include a piezo sounder or other audible device acting in unison with the electronic timer and so configured as to play a recorded message or emit a tone or sequence of tones. Suitable visual means include a light-emitting diode or other light-emitting device acting in unison with the electronic timer. 
     
    
     
         [0024]    A first embodiment of the invention will now be described by way of example only with reference to  FIGS. 1 to 8  of the accompanying drawings, in which: 
           [0025]      FIG. 1  shows, in perspective, the constituent parts of a product package consisting of a container with a screw cap incorporating an electronic-timer-and-latch-type locking system with visual indicator. 
           [0026]      FIG. 2  shows, with the outer cap in section, the closed product container prior to the activation of the electronic-timer-and-latch-type locking system. 
           [0027]      FIG. 3  shows, with the outer cap in section, the open product container with the electronic-timer-and-latch-type locking system activated. 
           [0028]      FIG. 4  shows, with the outer cap in section, the container and screw cap locked together by means of the electronic-timer-and-latch-type locking system. 
           [0029]      FIG. 5  shows the closed product container incorporating an electronic-timer-and-latch-type locking system with indication apertures. 
           [0030]      FIG. 6  shows the indication displayed in the indication apertures prior to the activation of the electronic-timer-and-latch-type locking system. 
           [0031]      FIG. 7  shows the indication displayed in the indication apertures upon activation of the electronic-timer-and-latch-type locking system. 
           [0032]      FIG. 8  shows the indication displayed in the indication apertures with the container and screw cap locked together by means of the electronic-timer-and-latch-type locking system. 
           [0033]    With reference to  FIGS. 1 to 8 , the product package incorporating an electronic-timer-and-latch-type locking system with visual indicator comprises a container  1  and a screw cap assembly  2  consisting of an outer cap  3 , with indication apertures  4 , locked together with, but free to rotate about, an inner cap  5  by means of a male rotatable annular snap fit  6  and a female rotatable annular snap fit  7 . The outer cap  3  is closed at one end by an end cap  8 , the positioning of which is determined by an index key  9  and index key slot  10 . The inner cap  5  forms a piston  11  at one end, over which is placed a spring  12  and an actuator  13 , the upper cylindrical outer face of which is printed with an indicator flag. Placed within the upper part of the actuator  13  is a timer/latch module  14  comprising a latch  15 , a shape-memory-alloy actuator wire  16 , a switch  17 , a battery  18 , and an electronic timer circuit with piezo sounder (not shown). 
           [0034]    At assembly, the upper parts of the locking tabs  19  on the actuator  13  are held against the underside of the slotted shoulder  20  within the outer cap  3  by means of the spring  12 . Clockwise movement of the outer cap  3  relative to the actuator  13  is prevented by the rotation limiters  21 , enabling the screw cap assembly  2  to be screwed onto the container  1  without relative movement between the outer cap  3  and inner cap  5 , the actuator  13  being prevented from rotating relative to the inner cap  5  by actuator guides  22  and guide slots  23  as shown in  FIGS. 1 and 2  and the indication, as shown in  FIG. 6 , is provided in the indication apertures  4 , as shown in  FIG. 5 . 
           [0035]    Upper friction stops  24  on the inner cap  5  and lower friction stops  25  on the container  1  are so proportioned as to ensure that the torsional force required to rotate the outer cap  3  about the inner cap  5 , with the spring  12  at its compressed length, is less than the torsional force required to unscrew the female thread (not shown) within the cap assembly  2  about the male thread  26  on the container  1 , as shown in  FIGS. 1 to 5 . 
           [0036]    When the outer cap  3  is rotated anticlockwise by fifty degrees about the inner cap  5 , the slots in the slotted shoulder  20  line up with the locking tabs  19  on the actuator  13 , the rotation limiters  21  preventing any further anticlockwise rotation of the outer cap  3  relative to the actuator  13  and the actuator  13 , under the force of the spring  12 , is moved upwards relative to the inner cap  5  until the switch  17  is closed by the slotted shoulder  20  on the outer cap  3  (thereby activating the electronic timer circuit) and the upper surface of the latch  15  makes contact with the underside of the slotted shoulder  20  on the outer cap  3  preventing any further vertical movement of the actuator  13  relative to the outer cap  3  and providing the indication as shown in  FIG. 7  in the indication apertures  4  as shown in  FIG. 5  and hence indicating to the user that the package has been opened and that the period after opening has commenced. 
           [0037]    As the locking tabs  19  are now situated in the slots of the slotted shoulder  20 , the actuator  13 , and hence the inner cap  5  cannot be rotated relative to the outer cap  3 , thereby enabling the screw cap assembly  2  to be disengaged and re-engaged with the container  1  in the manner of a common screw cap, as shown in  FIGS. 1 ,  3  and  5 . 
           [0038]    Once the period after opening has commenced in accordance with the above, the electronic timer circuit begins to count down from a pre-determined time period. 
           [0039]    From a pre-specified point in the count down, the piezo sounder periodically emits an audible signal to warn the user that the period after opening will soon expire. 
           [0040]    When the count reaches zero the electronic timer circuit connects power to the shape-memory-alloy actuator wire  16  causing it to contract thereby retracting the latch  15 . With the latch  15  retracted, the actuator  13 , under force of the spring  12  is free to move upwards relative to the outer cap  3  until the locking tabs  19  and slotted shoulder  20  disengage, the switch  17  is opened, and the actuator  13  and the end cap  8  make contact, as shown in  FIGS. 1 and 4 , thereby irreversibly providing the indication as shown in  FIG. 8  in the indication apertures  4  as shown in  FIG. 5 , and hence indicating to the user that the period after opening has elapsed. 
           [0041]    Should the period after opening elapse whilst the screw cap assembly  2  and the container  1  are disengaged, lower ratchet teeth  27  on the actuator  13  and upper ratchet teeth  28  on the end cap  8  enable the screw cap assembly  2  to be screwed onto the container  1 , a small compression of the spring  12  providing for the ratchet action as shown in  FIGS. 1 ,  4  and  5 . 
           [0042]    Once the upper friction stops  24  and lower friction stops  25  have made contact and the screw cap assembly  2  cannot be further rotated clockwise relative to the container  1 , any attempt to unscrew the screw cap assembly  2  from the container  1  will result in the outer cap  3  rotating about the inner cap  5  without any displacement of the inner cap  5  relative to the container  1  hence preventing the contents of the container  1  from being used as shown in  FIGS. 1 ,  4  and  5 . 
           [0043]    A second embodiment of the invention will now be described by way of example only with reference to  FIGS. 9 to 16  of the accompanying drawings, in which: 
           [0044]      FIG. 9  shows, in perspective, the constituent parts of a product package consisting of a container with a screw cap incorporating a spring-loaded piston, cylinder and gas-permeable-barrier-type, time-temperature-dependant locking system with visual indicator. 
           [0045]      FIG. 10  shows, with the outer cap in section, the closed product container prior to the activation of the spring-loaded piston, cylinder and gas-permeable-barrier-type, time-temperature-dependant locking system. 
           [0046]      FIG. 11  shows, with the outer cap in section, the open product container with the spring-loaded piston, cylinder and gas-permeable-barrier-type, time-temperature-dependant locking system activated. 
           [0047]      FIG. 12  shows, with the outer cap in section, the container and screw cap locked together by means of the spring-loaded piston, cylinder and gas-permeable-barrier-type, time-temperature-dependant locking system. 
           [0048]      FIG. 13  shows the closed product container incorporating a spring-loaded piston, cylinder and gas-permeable-barrier-type, time-temperature-dependant locking system with indicator window. 
           [0049]      FIG. 14  shows the indication displayed in the indicator window prior to the activation of the spring-loaded piston, cylinder and gas-permeable-barrier-type, time-temperature-dependant locking system. 
           [0050]      FIG. 15  shows the indication displayed in the indicator window upon activation of the spring-loaded piston, cylinder and gas-permeable-barrier-type, time-temperature-dependant locking system. 
           [0051]      FIG. 16  shows the indication displayed in the indicator window with the container and screw cap locked together by means of the spring-loaded piston, cylinder and gas-permeable-barrier-type, time-temperature-dependant locking system. 
           [0052]    With reference to  FIGS. 9 to 16 , the product package incorporating a spring-loaded piston, cylinder and gas-permeable-barrier-type, time-temperature-dependant locking system with visual indicator comprises a container  29  and a screw cap assembly  30  consisting of a transparent outer cap  31 , printed on its outer surfaces to provide an annular transparent indicator window  32 , locked together with, but free to rotate about, an inner cap  33  by means of a male rotatable annular snap fit  34  and a female rotatable annular snap fit  35 . The outer cap  31  is sealed at one end by a rotary seal  36  positioned within a rotary seal gland  37  on the inner cap  33  and at the other end by an end cap  38 , the positioning of which is determined by an index key  39  and index key slot  40 . The outer cap  31 , inner cap  33 , and end cap  38  are manufactured from a material with no, or a very low, permeability to air, thereby isolating the volume between the outer cap  31 , inner cap  33  and end cap  38  from fluctuations in atmospheric pressure and humidity. The inner cap  33  forms a piston  41  at one end, over which is placed a power spring  42 , a floating spring retainer  43 , a control spring  44  and an actuator  45  manufactured from a material with no, or a very low, permeability to air, the bore of the actuator  45  being sealed to the piston  41  by means of a piston seal  46  positioned within a piston seal gland  47 . Attached to the top of the actuator  45  in a gas tight manner is an indicator barrel  48 , the outer cylindrical face of which is printed with an indicator flag, with a seat  49  having an aperture at its centre, to which is adhered a gas-permeable barrier  50  so that any flow of air around the edges of the gas-permeable barrier  50  is prevented. Index pins  51  and index pin slots  52  ensure that the actuator  45  and indicator barrel  48  are correctly aligned and cannot rotate with respect to one another. 
           [0053]    At assembly, the upper parts of locking tabs  53  on the actuator  45  are held against the underside of slotted shoulders  54  within the outer cap  31  by means of the power spring  42  and the control spring  44 . Clockwise movement of the outer cap  31  relative to the actuator  45  is prevented by rotation limiters  55 , enabling the screw cap assembly  30  to be screwed onto the container  29  without relative movement between the outer cap  31  and inner cap  33 . The actuator  45  is prevented from rotating relative to the inner cap  33  by actuator guides  56  and guide slots  57  as shown in  FIGS. 9 and 10  and no indication, as shown in  FIG. 14  is provided in the indication window  32  as shown in  FIG. 13 . 
           [0054]    Upper friction stops  58  on the inner cap  33  and lower friction stops  59  on the container  29  are so proportioned as to ensure that the torsional force required to rotate the outer cap  31  about the inner cap  33 , with the power spring  42  and control spring  44  at their compressed lengths is less than the torsional force required to unscrew the female thread  60  on the cap assembly  30  about the male thread  61  on the container  29  as shown in  FIGS. 9 to 12 . 
           [0055]    When the outer cap  31  is rotated anticlockwise by fifty degrees about the inner cap  33 , the slots in the slotted shoulder  54  line up with the locking tabs  53  on the actuator  45 , the rotation limiters  55  preventing any further anticlockwise rotation of the outer cap  31  relative to the actuator  45  and the actuator  45 , under the force of the power spring  42 , is moved upwards relative to the inner cap  33  until the floating spring retainer  43  makes contact with the underside of the slotted shoulders  54  on the outer cap  31  thus causing, as a result of the relative displacement of the actuator  45  with respect to the piston  41 , an increase in the pressure within the outer cap  31  and a pressure drop in the bore of the actuator  45  as shown in  FIG. 11  and providing the indication as shown in  FIG. 15  in the indication window  32  as shown in  FIG. 13  and hence indicating to the user that the package has been opened and that the period after opening has commenced. 
           [0056]    As the locking tabs  53  are now situated in the slots of the slotted shoulder  54 , the actuator  45 , and hence the inner cap  33  cannot be rotated relative to the outer cap  31 , thereby enabling the screw cap assembly  30  to be disengaged and re-engaged with the container  29  in the manner of a common screw cap, as shown in  FIGS. 9 ,  11  and  13 . 
           [0057]    Once the period after opening has commenced in accordance with the above, air from the volume within the outer cap  31  is slowly transmitted to the bore of the actuator  45 , through the aperture in the indicator barrel  48  by means of the gas-permeable barrier  50  at a rate dependant upon temperature and the pressure differential between the bore of the actuator  45  and the volume within the outer cap  31  until such time as the force exerted by the control spring  44  between the floating spring retainer  43  and the actuator  45  is great enough to overcome the force exerted on the end of the actuator  45  due to the pressure differential between the bore of the actuator  45  and the volume within the outer cap  31  and the “break out” friction due to the piston seal  46 , at which point the control spring  44  pushes the actuator  45  upwards until the locking tabs  53  and slotted shoulder  54  disengage and the indicator barrel  48  and the end cap  38  make contact, enabling, as a result of this movement, the pressure in the bore of the actuator  45  and pressure in the volume within the outer cap  31  to equalise by means of the guide slots/pressure equalisation ports  57  as shown in  FIG. 12  and thereby irreversibly providing the indication as shown in  FIG. 16  in the indication window  32  as shown in  FIGS. 9 and 13  and hence indicating to the user that the period after opening has elapsed. 
           [0058]    Should the period after opening elapse whilst the screw cap assembly  30  and the container  29  are disengaged, the lower ratchet teeth  62  on the indicator barrel  48  and the upper ratchet teeth  63  on the end cap  38  enable the screw cap assembly  30  to be screwed onto the container  29 , a small compression of the control spring  44  providing for the ratchet action, as shown in  FIGS. 9 ,  12  and  13 . 
           [0059]    Once the upper friction stops  58  and lower friction stops  59  have made contact and the screw cap assembly  30  cannot be further rotated clockwise relative to the container  29 , any attempt to unscrew the screw cap assembly  30  from the container  29  will result in the outer cap  31  rotating about the inner cap  33  without any displacement of the inner cap  33  relative to the container  29 , hence preventing the contents of the container  29  from being used, as shown in  FIGS. 9 ,  12  and  13 . 
           [0060]    A third embodiment of the invention will now be described by way of example only with reference to  FIGS. 17 to 24  of the accompanying drawings, in which: 
           [0061]      FIG. 17  shows, in perspective, the constituent parts of a product package consisting of a container with a screw cap incorporating a viscous fluid and non-sealed-piston-type, time-temperature-dependant locking system with visual indicator. 
           [0062]      FIG. 18  shows, with the outer cap in section, the closed product container prior to the activation of the viscous fluid and non-sealed-piston-type, time-temperature-dependant locking system. 
           [0063]      FIG. 19  shows, with the outer cap in section, the open product container with the viscous fluid and non-sealed-piston-type, time-temperature-dependant locking system activated. 
           [0064]      FIG. 20  shows, with the outer cap in section, the container and screw cap locked together by means of the viscous fluid and non-sealed-piston-type, time-temperature-dependant locking system. 
           [0065]      FIG. 21  shows the closed product container incorporating a viscous fluid and non-sealed-piston-type, time-temperature dependant locking system with indicator window. 
           [0066]      FIG. 22  shows a graduated indicator flag for a viscous fluid and non-sealed-piston-type, time-temperature-dependant locking system. 
           [0067]      FIG. 23  shows the indication displayed in the indicator window upon activation of the viscous fluid and non-sealed-piston-type, time-temperature-dependant locking system. 
           [0068]      FIG. 24  shows the indication displayed in the indicator window with the container and screw cap locked together by means of the viscous fluid and non-sealed-piston-type, time-temperature-dependant locking system. 
           [0069]    With reference to  FIGS. 17 to 22 , the product package incorporating a viscous fluid and non-sealed-piston-type, time-temperature-dependant locking system with visual indicator comprises a container  64  and a screw cap assembly  65  consisting of a transparent outer cap  66 , printed on its outer surfaces to provide an annular transparent indicator window  67 , locked together with, but free to rotate about, an inner cap  68  by means of a male rotatable annular snap fit  69  and a female rotatable annular snap fit  70 . The outer cap  66  is closed at one end by an end cap  71 , the positioning of which is determined by an index key  72  and index key slot  73 . 
           [0070]    The inner cap  68  forms at one end a cylinder  74  over which is placed a spring  75  and an actuator  76  with an aperture at its centre equal in diameter to the diameter of the cylinder  74 . Attached to the top of the actuator  76  is an indicator barrel  77 , with an aperture  78  at its centre, the outer cylindrical face of which is printed with a graduated indicator flag as shown in  FIG. 22 , index pins  79  and index pin slots  80  ensuring that the actuator  76  and indicator barrel  77  are correctly aligned and cannot rotate with respect to one another. Fixed to the mouth of the cylinder  74  is a cylinder cap  81  to prevent the escape of a viscous fluid (not shown) contained within the cylinder  74 . Placed within the cylinder  74 , and hence within the viscous fluid, and passing through an aperture in the cylinder cap  81  and the aperture  78  in the indicator barrel  77 , is a piston rod  82  with a piston bulb  83  at one end and a piston snap fit  84  at the other end. The piston rod  82  is proportioned so that when the piston bulb  83  is at its lowest point within the cylinder  74 , the shoulder of the piston snap fit  84  is positioned at a distance greater than the thickness of the slotted shoulder  85  within the outer cap  66  above the upper, inner surface of the indicator barrel  77 . 
           [0071]    At assembly, the upper parts of the locking tabs  86  on the actuator  76  are held against the underside of the slotted shoulder  85  within the outer cap  66  by means of the spring  75 . Clockwise movement of the outer cap  66  relative to the actuator  76  is prevented by the rotation limiters  87 , enabling the screw cap assembly  65  to be screwed onto the container  64  without relative movement between the outer cap  66  and inner cap  68 , the actuator  76  being prevented from rotating relative to the inner cap  68  by actuator guides  88  and guide slots  89  as shown in  FIGS. 17 and 18  and no indication, as shown in  FIG. 23 , is provided in the indication window  67 , as shown in  FIG. 21 . 
           [0072]    Upper friction stops  90  on the inner cap  68  and lower friction stops  91  on the container  64  are so proportioned as to ensure that the torsional force required to rotate the outer cap  66  about the inner cap  68 , with the spring  75  at its compressed length, is less than the torsional force required to unscrew the female thread  92  on the cap assembly  65  about the male thread  93  on the container  64 , as shown in  FIGS. 17 to 21 . 
           [0073]    When the outer cap  66  is rotated anticlockwise by fifty degrees about the inner cap  68 , the slots in the slotted shoulder  85  line up with the locking tabs  86  on the actuator  76 , the rotation limiters  87  preventing any further anticlockwise rotation of the outer cap  66  relative to the actuator  76 , and the actuator  76  and hence the indicator barrel  77 , under the force of the spring  75 , is moved upwards relative to the inner cap  68  until the shoulder of the piston snap fit  84  on the piston rod  82  makes contact with upper, inner surface of the indicator barrel  77  thus providing, as a result of the relative displacement of the actuator  76  with respect to the inner cap  68 , the indication, as shown in  FIG. 23  in the indication window  67  as shown in  FIG. 21 , and hence indicating to the user that the package has been opened and that the period after opening has commenced. 
           [0074]    As the locking tabs  86  are now situated in the slots of the slotted shoulder  85 , the actuator  76 , and hence the inner cap  68  cannot be rotated relative to the outer cap  66 , thereby enabling the screw cap assembly  65  to be disengaged and re-engaged with the container  64  in the manner of a common screw cap, as shown in  FIGS. 17 ,  19  and  21 . 
           [0075]    Once the period after opening has commenced in accordance with the above, the force exerted by the spring  75 , through the actuator  76  and indicator barrel  77 , on the shoulder of the piston snap fit  84  causes the piston bulb  83  to slowly move through the viscous fluid contained within the cylinder  74  at a rate dependant upon the viscosity of the fluid, the viscosity of the fluid being a function of temperature, until the locking tabs  86  and slotted shoulder  85  disengage and the indicator barrel  77  and the end cap  71  make contact, as shown in  FIGS. 17 and 20 , thereby irreversibly providing the indication as shown in  FIG. 24  in the indication window  67  as shown in  FIG. 21 , and hence indicating to the user that the period after opening has elapsed. 
           [0076]    Should the period after opening elapse whilst the screw cap assembly  65  and the container  64  are disengaged, lower ratchet teeth  94  on the indicator barrel  77  and upper ratchet teeth  95  on the end cap  71  enable the screw cap assembly  65  to be screwed onto the container  64 , a small compression of the spring  74  providing for the ratchet action as shown in  FIGS. 17 ,  20  and  21 . 
           [0077]    Once the upper friction stops  90  and lower friction stops  91  have made contact and the screw cap assembly  65  cannot be further rotated clockwise relative to the container  64 , any attempt to unscrew the screw cap assembly  65  from the container  64  will result in the outer cap  66  rotating about the inner cap  68  without any displacement of the inner cap  68  relative to the container  64  hence preventing the contents of the container  64  from being used as shown in  FIGS. 17 ,  20  and  21 . 
           [0078]    A fourth embodiment of the invention will now be described by way of example only with reference to  FIGS. 25 to 29  of the accompanying drawings, in which: 
           [0079]      FIG. 25  shows in perspective, the constituent parts of a product package consisting of a container with a screw cap incorporating a tamper-evidence-only-type locking system. 
           [0080]      FIG. 26  shows with the outer cap in section, the closed product container prior to the activation of the tamper-evidence-only-type locking system. 
           [0081]      FIG. 27  shows, in perspective, the closed product container prior to the activation of the tamper-evidence-only-type locking system. 
           [0082]      FIG. 28  shows, with the outer cap in section, the open product container after activation of the tamper-evidence-only-type locking system. 
           [0083]      FIG. 29  shows in perspective, the open product container after activation of the tamper-evidence-only-type locking system. 
       
    
    
       [0084]    With reference to the accompanying drawings, the package incorporating a tamper-evidence-only-type locking system comprises a container  96  and a screw cap assembly  97  consisting of an outer cap  98  locked together with, but free to rotate about, an inner cap  99  by means of a male rotatable annular snap fit  100  and female rotatable annular snap fit  101  and containing a spring  102 , and an actuator  103  with locking tabs  104  the outer faces of which are printed with an indicator flag  105 . The outer cap  98  is manufactured from a transparent material and printed on its outer surfaces to provide a transparent indicator window  106 , as shown in  FIGS. 25 to 29 . 
         [0085]    At assembly, the upper parts of the locking tabs  104  on the actuator  103  are held against slotted shoulder  107  within the outer cap  98  by means of the spring  102 . Clockwise movement of the outer cap  98  relative to the actuator  103  is prevented by rotation limiters  108 , enabling the screw cap assembly  97  to be screwed onto the container  96  without relative movement between the outer cap  98  and inner cap  99 , actuator  103  and spring  102 , the actuator  103  being prevented from rotating relative to the inner cap  99  by actuator guides  109  and guide slots  110 , as shown in  FIGS. 25 ,  26  and  27 . 
         [0086]    Upper friction stops  111  on the inner cap  99  and lower friction stops  112  on the container  96  are so proportioned as to ensure that the torsional force required to rotate the outer cap  98  about the inner cap  99  is less than the torsional force required to unscrew the inner cap  99  about the male thread  113  on the container  96 , as shown in  FIGS. 25 and 26 . 
         [0087]    When the outer cap  98  is rotated anticlockwise by fifty degrees about the inner cap  99 , the slots in the slotted shoulder  107  line up with the locking tabs  104  on the actuator  103 , the rotation limiters  108  preventing any further anticlockwise rotation of the outer cap  98  relative to the actuator  103 . The actuator  103 , under the force of the spring  102 , is then moved into contact with the upper part of the outer cap  98  thus irreversibly locking the outer cap  98  to the inner cap  99  and enabling the indicator flags  105  to be viewed through the indicator windows  106  and providing a permanent indication to the user that the package has been opened. The screw cap assembly  97  may now be disengaged and re-engaged with the container  96  in the manner of a common screw cap, as shown in  FIGS. 25 ,  28  and  29 . 
         [0088]    The retraction of the latch may be achieved by the contraction of a shape-memory-alloy actuator wire as shown in the first embodiment of the invention or by any other suitable thermal shape-memory-alloy effects. 
         [0089]    The seal between the cylinder of the actuator and the piston of the inner cap may be achieved by means of an ‘O’ ring as shown in the second embodiment of the invention or by any other suitable means such as a ‘U’ seal, ‘X’ seal, or a composite seal comprising, for example, a polymer jacket energised by a metallic spring, a polymer jacket energised by an ‘O’ ring or a polymer jacket energised by a spring element or elements formed on the end of the piston, by means of a single or multiple shot injection-moulding process, as an integral part of the inner cap.