Abstract:
An indicator system with a dispenser providing controlled release of a volatile material contained within a dispenser, which indicates the exhaustion of the volatile material. The dispenser includes a blister that contains a vapor permeable membrane that collapses on a bottom wall due to internal vacuum forces created by the evacuation of volatile material. As the membrane collapses the remaining volatile material migrates to the periphery of the dispenser thereby indicating exhaustion of the volatile material.

Description:
FIELD OF THE INVENTION 
   The invention generally relates to indicators for expiration of usable materials. More specifically, the invention relates to an expiration indicator of a dispenser for volatile materials that permits a more desirable appearance than the prior art. 
   BACKGROUND 
   This application is related to the following co-pending applications filed concurrently herewith: Volatile Material Dispensing System, Ser. No. 10/881,816 and Volatile Material Dispensing System with Illuminating Means, Ser. No. 10/880,885. 
   BACKGROUND ART 
   A variety of packages have been used to contain volatile materials and permit the controlled dispensing of them as vapors into the ambient air. The prior art describes in detail the use of permeable membranes as well as other manners to disperse volatile material from a given container. A number of the volatile material dispensers have also utilized various forms of expiration or use-up indicators. 
   U.S. Pat. No. 5,259,555 describes a wooden air freshener with fragrance loading chamber. Air freshening oil is placed in a chamber and migrates through the wood along the capillaries of the wood grain until it reaches the outside wooden surface of the container. The wood acts as a metering device for the gradual release of the air freshening agent. As the oil evaporates, the wooden member loses its luster and lightens in appearance, signaling that more air freshening agent is needed. This change in appearance allows an observer to easily determine whether the chamber needs to be refilled. 
   U.S. Pat. No. 6,555,068 describes an apparatus incorporating air modifying agents. This air modifying agent and an electrolyte are entrained in a gel-based aqueous reservoir which contacts a pair of electrodes. The extent of exhaustion of the air modifying agent from the reservoir corresponds to the extent of exhaustion of electrode activity, whereby the operability of the electrical device indicates the presence of air modifying agent in the reservoir. 
   U.S. Pat. No. 4,293,095 describes an air treating device having an indicator system to signal exhaustion of the operative fluid. 
   U.S. Pat No. 2003/0089791 describes a vaporization indicator film. During use, the semi-porous membrane visually indicates transmission of active ingredient vapor to the consumer through use of pores that are normally opaque and become saturated and turn from opaque to clear when in use. Upon depletion of the volatile material from the reservoir and subsequently from the membrane, the membrane turns opaque again. 
   It is known in the art to utilize fumed silica gelling agents to provide an expiration indicator for solution-diffusion delivery systems. With respect to these systems, the silica particles are suspended in the active volatile liquid, and as the active liquid diffuses, the concentration of the silica particles increases. Following a period of time and near the expiration of such a device, a cracked residue results and the contents of the dispenser are cracked and crumbly to indicate a level of expiration. This appearance is unattractive and unpleasant. 
   Prior art volatile material dispensers utilize tray-like holders that are formed from thermoformed plastic materials. Volatile material in these holders contains a fumed silica gelling agent that is blended with the fragrance and suspended in the volatile material. Subsequent to exhaustion of the volatile material the fumed silica agent remains leaving a unattractive appearance. Fumed silica increases the viscosity of the volatile material. As volatile material exhaustion occurs the concentration of the agent increases as well as viscosity, which solidifies the remaining material and prevents it from easily migrating within the holder. As a result of using these silica gelling agents, a relatively deep tray-like holder is necessary. A vapor void forms in the deep tray-like holder and the silica gel fills up in the vapor filled chamber, crumbles and adversely affects active ingredient diffusion. As the volatile material is diffused through the membrane the silica gelling agent remains. The presence of the silica gelling agent interferes with the surface area contact of the remaining volatile material and the membrane. This reduction of surface area contact affects the diffusion rate of the volatile material. The reduced diffusion rate prevents the volatile material from diffusing at a constant or nearly constant rate up until approximate expiration. As a result, the diffusion of volatile material is substantially less than 100%. In prior art dispensers, approximately 50–60% diffusion was customary. An improved volatile material holder is needed that will provide an accurate indication of volatile material expiration and provide an efficient, steady and predictable level of diffusion. Part of the problem with the prior art is that the level of diffusion decreases substantially as the expiration of the dispenser approaches. The present invention solves this problem by providing for an evacuatable and shallower volatile material dispenser that increases the surface area contact between the membrane and the volatile material. Prior art air freshener dispensers can be clearly identified as such, leading to a social stigma. The present invention presents a decorative displaying means which prevents this socially detrimental stigma. The present invention solves this problem and solves the problem of knowing when the dispenser is close to expiration or already expired. 
   SUMMARY OF THE INVENTION 
   In accordance with a first aspect of the invention, a volatile material expiration indicating system is provided that includes an evacuatable volatile material dispenser, including a blister having a first surface and a vapor permeable membrane sealed to a periphery of said first surface. The volatile material is comprised of an active ingredient, thickening agent and a colored dye, wherein diffusion of the volatile material through the permeable membrane results in a pressure gradient between the ambient atmosphere and the dispenser. As the volatile material leaves the blister, the blister transitions from a first filled condition to a second collapsed condition. The vacuum forces within the blister hold the membrane against the surface of the volatile materials as they decrease in quantity in the blister, and thereby provide a sustained surface area contact between the membrane and the volatile material. 
   In accordance with another aspect of the invention, the indicating system further comprises a vapor impermeable laminate releasably connected to the vapor permeable surface, wherein the laminate prevents the diffusion of said volatile substance. The laminate may be peeled from the dispenser in order to start the diffusion of the volatile material through the membrane. 
   In accordance with a third aspect of the invention, the indicating system further includes a displaying means wherein the displaying means is a translucent frame structure having a transparent wall, a front side and a back side. The blister is attached to the back side of the frame and can be viewed through the transparent wall. The volatile material contained within the blister may be colored with a dye, and said color would be used in conjunction with the indicating system to act in a decorative manner. 
   In accordance with another aspect of the invention, the displaying means further includes a decorative image, wherein said image is viewable throughout said system&#39;s life cycle. 
   Other features will become apparent to those skilled in the art from a review of the following detailed description, taken in conjunction with the drawings and the appended claims. While the disclosed dispenser is susceptible of embodiments in various forms, described below are specific embodiments that are intended as illustrative (and not intended to limit the disclosure to the specific embodiments described herein). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded back perspective view of the system. 
       FIG. 2  is a perspective view of the dispenser shown in  FIG. 1 . 
       FIG. 3  is a perspective view of the assembled system shown in  FIG. 1 . 
       FIG. 4  is an exploded front perspective view of the system. 
       FIG. 5  is a back face view of the system with a dispenser in the first filled condition. 
       FIG. 6  is a sectional view of the system taken substantially along line  6 — 6  of  FIG. 5 . 
       FIG. 7  is a partial enlarged sectional view of the dispenser shown in  FIG. 6 . 
       FIG. 8  is a front face view of the system with a partially evacuated dispenser. 
       FIG. 9  is a sectional view of the system taken substantially along line  9 — 9  of  FIG. 8 . 
       FIG. 10  is a partially enlarged sectional view of the system shown in  FIG. 9 . 
       FIG. 11  is a partially enlarged sectional view of the dispenser taken substantially along line  11 — 11  of  FIG. 8 . 
   

   DETAILED DESCRIPTION 
   Referring to  FIGS. 1 and 2 , a volatile material expiration indicating system  10  is illustrated, the system  10  having an evacuatable material dispenser  12 , a decorative image  14 , and a display frame  16  for holding the dispenser  12 . The decorative image  14  is attached to the frame  16 . 
   The dispenser  12  includes a blister  18 , a peripheral flange  20 , and an impermeable laminate  22  releasably adhered to said blister  18 . The blister  18  includes a non-porous permeable membrane  24  comprised of low density polyethylene (LDPE), and a cup-shaped structure  26 . Cup  26  includes a recycled polyethylene terephthalate (RPET) layer adhesively bonded to a nylon laminate. The nylon laminate includes a layer of ethylene vinyl acetate (EVA) coextruded to each side of a middle nylon layer. The cup  26  includes a bottom wall  28  and four side walls  30 , that in conjunction with the membrane  24  acts as a sealed reservoir to contain the volatile material  32  ( FIG. 7 ). 
   The laminate  22  includes a layer of polypropylene, aluminum foil, and polyester. The polypropylene is adhesively bonded to the aluminum foil layer, which is adhesively bonded to the polyester layer. An extrusion bonding material is used to bond the layers together. Laminate  22  preferably has a thickness of between 0.1 to 0.2 mm. The polyester layer is suitable for printing and is the outer surface of laminate  22 . Preferably the membrane  24  and polypropylene layer of laminate  22  are coextruded when the blister is manufactured. The coextrusion permits for the laminate  22  to be peelably removed from the blister  18  while avoiding unnecessary reactions between an adhesive and the volatile material  32  during diffusion. 
   Cup  26  preferably has a thickness between 0.3 to 0.4 mm. The cup  26  is generally rectangular and preferably square with overall dimensions of about 3–5 mm thick, 50–60 mm long and 50–60 mm wide. Each of its four sidewalls  30  has a corresponding width of 3–5 mm and a length of 50–60 mm. Sidewalls  30  taper slightly outward as one moves from the bottom wall to the flange  20 . Bottom wall  28  is also generally rectangular and has width of 48–58 mm and a height of 48–58 mm. The sidewalls  30  and bottom wall  28  of cup  26  are preferably thermoformed from a single sheet of the RPET and nylon laminate that is heated, then either blown or pressed into the flange-and-cup arrangement shown in the FIGURES. Preferably the cup  26  is clear and translucent, allowing for the visibility of the volatile material  32  contained within the blister  18 . 
   Cup  26  contains relatively shallow side walls  30 , as stated above. The shallow nature of the blister  18  allows for the membrane  24  to collapse upon the bottom wall  28 . Diffusion of the volatile material  32  through the membrane  24  creates collapsing of membrane  24  upon wall  28  that maintains contact between the volatile material  32  and the membrane  24 . The contact allows for a greater percentage of overall volatile material  32  diffusion and allows for indication of volatile material  32  expiration. 
   Peripheral flange  20  is preferably planar. It is coupled to and extends outward from the top edges of the cup  26  (e.g. the upper edges of sidewalls  30 ). Flange  20  is integrally formed with the cup  26  in a thermoforming process, as described in the preceding paragraph. 
   Following placement of the volatile material  32  into the cup  26 , a seal is made between the flange  20  and the permeable membrane  24  thereby forming the dispenser  12 . At the same time laminate  22  may be attached to the blister  18  by having already been adhered to the membrane  24 . The membrane  24  and laminate  22  may be attached to the flange  20  of the blister  18  using any conventional means, such as an adhesive, heat sealing, crimping, or the like. The seal must be air-tight so as to prevent leakage of air or volatile material  32 . Most preferably the membrane  24  and the laminate  22  are sealed to the cup  26  in a single step. The volatile material  32  does not completely fill the void within the blister  18 . A relatively small amount of air can be tolerated in dispenser  12  following the creation of blister  18 . Preferably the air in the sealed blister is no more than 3–6% of the overall volume of the blister  18 . As the volatile material diffuses out of dispenser  12  no air enters the blister  18  through the permeable membrane  24 . The membrane  24  is configured to distend and collapse without passage of air into the dispenser. 
   When the volatile material is to be dispensed, the laminate  22  is removed from the blister  18 . Preferably, the removal process will occur by a user grasping an end of the laminate  22  and peeling it off the blister  18 . A tab, extension, or other means for grasping (not shown) may be included as an extension of the laminate  22  to aid in removal of the laminate  22 . The extension may be at the corners, ends, or on the surface of the laminate  22 . 
   Permeable membrane  24  has a thickness of about 0.05 to 0.15 mm and has a density preferably between 0.88 and 0.95 grams/cubic centimeter. It is formed integrally with laminate  22  and is heat fused to flange  20  such that membrane  24  extends across the entire cup  26 . Membrane  24  encloses and seals the cup  26  with the volatile material  32  stored inside thereby forming a thin sealed container impermeable to the volatile material  32  stored inside. This container remains impermeable until the user grasps a corner of laminate  22  and peels laminate  22  from the membrane  24 , thereby exposing permeable membrane  24  and permitting the volatile material  32  to migrate through the permeable membrane  24  and diffuse into the ambient air. The membrane  24  is preferably comprised of LDPE and is clear and translucent, allowing for visibility of the volatile material contained within the blister  18 . 
   Frame  16  is a rectangular structure, preferably square, with four substantially equal-sized side walls  34 , a front face  36  ( FIG. 4 ) and a rear face  38 . Frame  16  preferably has a thickness of between 12 and 22 mm and a height and width of between 70 and 90 mm. More preferably frame  16  has a width of approximately 15 mm and height of approximately 80 mm. 
   Front face  36  has a stepped recess  40  ( FIG. 4 ). Recess  40  gives frame  16  the appearance of a picture frame surrounding and framing the bottom (or back) wall  42  ( FIG. 4 ) of the recess  40 . In the preferred embodiment, shown in  FIGS. 6 and 9 , the walls of recess  40  appear in cross section to have steps or curves  44  in the manner of an ornate picture frame. The recess  40  preferably centered in the front face  36  and is disposed away from the side walls  34 . The recess  40  does not extend to the edge of the front face  36 . Instead, front face  36  appears as a border extending around the edges of the recess  40 , having a constant width between 2 and 4 mm. 
   Wall  42  is preferably transparent or translucent to permit light to pass through. Wall  42 , in that regard, may function as a window that permits the viewer (from the front) to visually perceive what is directly behind wall  42 . 
   Rear face  38  of frame  16  also is recessed. This recess is similarly stepped, and is configured to completely receive dispenser  12 , with dispenser  12  positioned so that the membrane  24  surface is substantially flush with rear face  38 . The recess is also preferably stepped, having a shallower peripheral recess  46  extending all the way around rear face  38  and a deeper central recess  48 . The deeper central recess  48  is configured and dimensioned to receive cup  26 , and the peripheral recess  46  is configured and dimensioned to receive and support flange  20 . In short, the central recess  48  and peripheral recess  46  combined have a negative shape that is the same as that of dispenser  12 . 
   Peripheral recess  46  preferably has an adhesive, spring clip, or other mechanical or adhesive retaining means that is configured to hold flange  20  in place. Flange  20  and peripheral recess  46  may be adhered to one another through the use of any adhesive, or alternatively though a mechanical means, such as interference fit, or separate mechanical fastener, such as a spring clip. When an adhesive  49  is used (as shown herein), a flange-to-frame adhesive may be chosen to either permanently adhere the flange  12  to the display frame  16  or, alternatively, be releasably adhered for easy removal. In this manner, frame  16  can be a permanent and reusable item to which a succession of replacement dispensers  12  are affixed and later removed and replaced. 
   Central recess  48  is deeper than peripheral recess  46  since it must accommodate the greater combined thickness of cup  26 , flange  20  and membrane  24 . The bottom of cup  26  is adjacent to and preferably slightly spaced apart from the bottom  50  of central recess  46 . Central recess  48  and peripheral recess  46  are preferably centrally spaced from the internal edges of rear face  38 . 
   The distance between the bottom  50  ( FIG. 1 ) of central recess  48  and the bottom  52  ( FIG. 4 ) of recess  40  on the front face  36  of frame  16  (i.e. the thickness of wall  44 ), is preferably between 2 and 5 mm. Wall  42  may be transparent or translucent. The translucent properties of wall  42  enables the user to easily identify when the volatile material  32  has nearly all diffused through membrane  24 . Additionally, the translucent properties of wall  42  have a decorative function. The frame is best shown ( FIGS. 3 and 4 ) to represent the translucent properties of wall  42 . 
   The display frame  16  may be constructed from a variety of compositions, including glass, injection-molded plastic, and rubber. In the preferred embodiment, the display frame  16  is constructed from molded glass that is clear and transparent. 
   Blister  18  of the dispenser  12  is filled with a volatile material  32 . It is particularly suited for use in holding a volatile material  32  comprising an active ingredient, which is to be slowly diffused into the surrounding atmosphere, such as a fragrance, air freshener, insect repellant insecticide. In addition to the active ingredient the preferred embodiment includes a dye and thickening agent that color and thicken the volatile material  32 . The dye and thickening agent most preferably comprise less than 2% of the overall composition. 
   Insecticides and other related chemicals may also be utilized as the volatile material  32 . Where the user does not wish to have an unsightly insect repellant device, but requires the utility of a repellant, the decorative system is advantageous and blends in with the surrounding décor. The indicator system  10  allows for such a volatile material  32  to be released while having a decorative appearance. 
   When volatile material  32  is a fragrance, the fragrance can be relatively simple in composition, or can be a complex mixture of natural and/or synthetic chemical compounds. Various mixtures of volatile materials for use in the indicator system may comprise as few as two chemicals and as many as over one hundred. Most conventional fragrance materials are synthetic or naturally derived volatile essential oils, such as, for example, lemon, mandarin, cedar leaf, clove leaf, cedar wood, oil of bergamot, bitter orange, geranium, lavender, orange, lavandin, neroli, rose absolute, cinnamon, and the like. Synthetic types of fragrance composition, either alone or in combination with natural oils, are described in U.S. Pat. Nos. 4,314,915; 4,411,829; and 4,434,306, which are incorporated herein by reference. 
   The image  14  ( FIGS. 1 and 8 ) may be graphic or textual. It may read, for example, “Please Replace.” The image may be positioned in a plurality of positions, including but not limited to the following: front face  36  of frame, rear face  38  of frame, or upon the bottom wall  28  ( FIG. 4 ). The image may be printed upon a layer of primed polyester that is adhesively adhered to the system  10 , as described above. Alternatively, the image may be thermoformed into the bottom wall  28  or may be molded into the decorative frame  16 . 
   The image  14  is shown in the shape of a tree, but may also be chosen from festive images used during various holiday seasons, such as a Christmas tree, menorah, Easter egg, valentine heart, pumpkin, and the like. Additionally, the color of the volatile material may be chosen in conjunction with such images to aid in celebration of the respective holidays. Multiple color combinations may be utilized in accordance to the decorative tastes of the user. The image  14  may be a plurality of other images that may include flowers, wildlife, cosmic displays, sporting related, and the like. 
   Depending upon the type and amount of dye utilized in conjunction with the volatile material  32  and the positioning of the image  14 , either in front of or behind volatile material  32 , the image  14  may or may not be viewable when the blister  18  is filled. Preferably the image is not viewable until a majority of the volatile material  32  has been released, and the dispenser  12  nears an empty or second condition, so as to more clearly indicate use-up of the volatile material  32 . Most preferably, the image  14  is viewable when the dispenser  12  is full, empty, and at any point in between. However, the image  14  would be more readily viewable when the dispenser  12  is empty, in order to enhance the decorative nature in conjunction with dispenser  12  use-up. For purposes of the present invention, expiration of the volatile material  32  or system  10  refers to use-up of the volatile material  32 . 
   The preferred embodiment of the invention allows for the indication that the dispenser  12  is empty or near empty and little or no volatile material  32  remains. The indication of expiration is easily viewed following the near complete diffusion of the volatile material  32 . However, diffusion of the volatile material  32  is dependent upon the type of membrane utilized. Preferably dispenser  12  will last 30–45 days before it is empty. Of course, this can be changed based upon the material used as a membrane, the thickness of the membrane, surface area of the membrane, volume of the blister  18 , volume of volatile material  32  when the dispenser  12  is filled, and which particular volatile material composition is utilized. 
   When packaged the dispenser  12  is filled ( FIG. 7 ) with volatile material  32  and laminate  22  is adhered to the permeable membrane  24 . There is virtually no diffusion of volatile material  32  when the dispenser is filled and laminate  22  covers membrane  24 . Following removal of laminate  22 , the system  10  begins to transition towards an empty or second condition. Of course, there may be a small amount of volatile material  32  that remains and the dispenser  12  will be considered to have reached the second condition. As the volatile material  32  diffuses through the membrane  24 , the membrane  24  slowly collapses upon the bottom wall  28 . Following diffusion of the volatile material  32  across the membrane  24  there is less material  32  contained within dispenser  12 . Virtually no new air enters the dispenser  12  subsequent to diffusion of volatile material  32 . The result of this is a pressure gradient across the membrane  24 , with a higher pressure existing in the ambient air than the pressure in dispenser  12 . The pressure gradient causes the ambient air to exert a net positive pressure upon the dispenser, which presses the membrane  24  against the remaining volatile material  32  and ultimately the bottom wall  28 . Continued diffusion of the volatile material  32  increases the force exerted upon the membrane  24 , which causes the remaining volatile material to migrate from a center of wall  28  towards the periphery of wall  28 . Continued migration and diffusion of the volatile material  32  results in an increasing surface area contact between membrane  24  and wall  28  until dispenser  12  is empty, or nearly empty. Increasing contact between the membrane  24  and the wall  28  allows for the image  14  to be more readily viewable. The pressure gradient ultimately resulting in migration of the volatile material  32  may also be viewed as occurring due to an increasing compressed vacuum presence within dispenser  12  as the volatile material continues to diffuse across membrane  24 . 
   Referring to  FIGS. 8–11 , a small amount of volatile material  32  remains within the dispenser  12  when it is nearly empty, and is present in the form of a ring-like appearance towards the periphery of the bottom wall  28 . A dye and thickener combine to comprise approximately 2% of the overall volatile material composition of the system  10  at the first condition. Preferably a higher concentration of dye is present in the volatile material  32  when the dispenser  12  is nearly empty, as the dye substantially does not diffuse across membrane  24 . This results in a more readily viewable ring-like appearance. The color of the ring-like image is more intense in color than the coloration of the first condition because of the increased concentration of dye material. In the second condition the thickener and dye comprise nearly all of the material left within the dispenser  12 . Of course, this may change dependant upon the particular dye composition and thickening agent utilized in the volatile material  32 . As the system  10  approaches and is in a second condition, the nearly expired dispenser  12  can be seen so as to indicate its end of life. 
   When the dispenser  12  is full, or in the first condition, a decorative image may not be seen through the colored or opaque volatile material  32 . As the dispenser  12  empties, or reaches the second condition, the decorative image  14  becomes viewable indicating a level of expiration or use-up. Alternatively, the decorative image  14  may be viewable while the dispenser  12  is both full and empty. Indication of volatile material  32  use-up may be achieved by more readily viewing image  14  as a result of the absence of colored volatile material within the dispenser  12 . Dependent upon the specific volatile material composition, there may be numerous chemicals that either do not diffuse through the permeable membrane  24  or diffuse slower than the designed active ingredients or fragrances. Active ingredients may include chemicals such as esters, aldehydes, ketones, terpenes, alcohols, and aromatic compounds. As a result, material may be left within the blister  18  as it is nearly at or reaches a level of expiration in which replacement is necessary. 
   It is understood that the present invention is not limited to the embodiments described above and illustrated herein, but encompasses any and all variations falling within the scope of the appended claims. 
   INDUSTRIAL APPLICABILITY 
   The invention provides a volatile material exhaustion indicating system for volatile material dispensers.