Title:
HINGED PLASTIC CONTAINER
United States Patent 3576271
Abstract:
A container thermoformed from semirigid plastic sheet material, having separate cover and base portions connected by a hinge including a tongue in the cover portion which is insertable into a slit in the base portion, and which includes detent means on said tongue for preventing withdrawal of the tongue from the slit. Hinge is free acting, tending neither to pop cover open when closed, nor closed when open. With this hinge construction cover can be manufactured from a transparent material for display or functional purposes, even though base is manufactured from an opaque material.
Application Number:
04/813604
Publication Date:
04/27/1971
Filing Date:
04/04/1969
View Patent Images:
Export Citation:
Assignee:
Plastofilm, Inc. (Wheaton, IL)
Primary Class:
Other Classes:
220/377, 220/836
International Classes:
B65D43/16; B65D45/16; B65D51/04
Field of Search:
220/31.31 (SR)/ 220/31.31,(RR) 229/44 206/45.19,45.28,45.34
Primary Examiner:
Lowrance, George E.
Claims:
I claim
1. A container comprising a base piece and a top piece thermoformed from semirigid plastic sheet, the base piece having an opening means in the top thereof and a generally horizontal surface surrounding said opening means, the top piece having a generally horizontal surface about its periphery and positioned in juxtaposition to said surface of the base piece, one of said surfaces defining a flat tongue projecting outwardly therefrom approximately parallel to the one surface, said tongue having a given thickness, the other of said surfaces having an upright slit therethrough, said slit having a width less than said given thickness, said tongue extending through said slit and forming a hinge-type connection between the pieces.
2. A container as set forth in claim 1, wherein said other surface defines openings at each end of the slit extending in one direction from the slit, whereby the slit and the openings define a tab having three sides.
3. A container as set forth in claim 2, wherein said slit is a cut so that the plastic edges on opposite sides thereof are substantially abutting when the tongue is not positioned therebetween.
4. A container as set forth in claim 2, wherein said other surface is on said base piece and said surface is on said top piece.
5. A container as set forth in claim 4, wherein said base piece is formed of an opaque plastic and said top-opening means is divided into a plurality of individual openings, a plurality of removable transparent plastic trays positioned respectively in the individual openings.
6. A container as set forth in claim 5, wherein said top piece is transparent plastic.
7. A container as set forth in claim 1, wherein said base piece is formed of an opaque plastic and said top-opening means is divided into a plurality of individual openings, a plurality of removable transparent plastic trays positioned respectively in the individual openings.
8. A container as set forth in claim 7, wherein said top piece is transparent plastic.
1. A container comprising a base piece and a top piece thermoformed from semirigid plastic sheet, the base piece having an opening means in the top thereof and a generally horizontal surface surrounding said opening means, the top piece having a generally horizontal surface about its periphery and positioned in juxtaposition to said surface of the base piece, one of said surfaces defining a flat tongue projecting outwardly therefrom approximately parallel to the one surface, said tongue having a given thickness, the other of said surfaces having an upright slit therethrough, said slit having a width less than said given thickness, said tongue extending through said slit and forming a hinge-type connection between the pieces.
2. A container as set forth in claim 1, wherein said other surface defines openings at each end of the slit extending in one direction from the slit, whereby the slit and the openings define a tab having three sides.
3. A container as set forth in claim 2, wherein said slit is a cut so that the plastic edges on opposite sides thereof are substantially abutting when the tongue is not positioned therebetween.
4. A container as set forth in claim 2, wherein said other surface is on said base piece and said surface is on said top piece.
5. A container as set forth in claim 4, wherein said base piece is formed of an opaque plastic and said top-opening means is divided into a plurality of individual openings, a plurality of removable transparent plastic trays positioned respectively in the individual openings.
6. A container as set forth in claim 5, wherein said top piece is transparent plastic.
7. A container as set forth in claim 1, wherein said base piece is formed of an opaque plastic and said top-opening means is divided into a plurality of individual openings, a plurality of removable transparent plastic trays positioned respectively in the individual openings.
8. A container as set forth in claim 7, wherein said top piece is transparent plastic.
Description:
BACKGROUND OF THE INVENTION
Thermoformed plastic containers fabricated from a single sheet, and which include a receptacle, or base portion and a cover portion integrally joined by a plastic hinge have serious shortcomings. The "memory" of integral plastic hinges causes them to tend to pop a cover portion open when the cover is closed, or, after the container has been closed for a long period of time, the hinges often tend to close, or partially close the cover when the cover is opened.
Moreover, it is often desirable to provide a container having a base or receptacle portion fabricated from a first material, for example, 0.030 high-impact opaque styrene, and a cover portion manufactured from a second material, for example, transparent 0.024-inch polyvinyl chloride. Such construction is virtually impossible using integral plastic hinge design. However, such multimaterial containers, which would be useful in displaying products such as cosmetics, corsages, baby shoes, and in enclosures requiring transparency for functional reasons, as in diagnostic test trays and the like, must be inexpensively manufactured to achieve widespread use. Moreover, it is highly desirable that the hinge means provided be free acting, that is, having no tendency to reclose or pop open.
Thus, it is an object of this invention to provide a two-piece container thermoformed from semirigid plastic sheet, for example, a container produced by the well-known vacuum forming techniques, which container utilizes a two-piece plastic hinge. It is another object of this invention to provide a plastic hinge which is free acting, that is, having no tendency to reclose, or pop open. It is a further object of this invention to provide plastic hinge construction making it possible to manufacture containers which utilize a first material in the receptacle portion, and a second, transparent material in the cover portion. It is also an object of this invention to provide such plastic containers, which are simply and economically produced.
These and other objects, which will be apparent hereinafter are all achieved in accordance with the invention which is described in detail herein.
SUMMARY OF THE INVENTION
This invention relates to containers manufactured from semirigid, thermoformed plastic sheet material having a two-piece plastic hinge comprising a slit in a base portion of the container, and a tongue in the cover portion, which tongue is constructed to be insertable into the slit, and includes detent means for obstructing withdrawal of the inserted tongue from the slit.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional plan view taken approximately along the line 1-1 of FIG. 2.
FIG. 2 is an elevational cross-sectional view taken approximately along the line 2-2 of FIG. 1.
FIG. 3 is an enlarged fragmentary elevational view taken approximately along the line 2-2 of FIG. 1 showing transposition of cover.
FIG. 4 is a plan view of an alternative embodiment of this invention in which the cover portion is partially shown removed.
FIG. 5 is an elevational cross-sectional view taken approximately along the line 5-5 of FIG. 4.
FIG. 6 is an elevational cross-sectional view also taken along the line 5-5 of FIG. 4 showing the transposition of the lid.
FIG. 7 is an enlarged fragmentary elevational view shown detail of detent means on the hinge tongue of the lid shown in FIG. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Although the following disclosure offered for public dissemination, in return for the grant of a patent, is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose; as it is these that meet the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts are found.
In accordance with this invention plastic packages, generally 10, 10', include a base or receptacle portion, generally 11, 11', and cover or lid portion, generally 12, 12'. Described in this application are two preferred embodiments, one being illustrated in FIGS. 1 through 3, and another being illustrated in FIGS. 5 through 7. Parts in the two embodiments which correspond to each other are given the same number identification in the description which follows, except that parts shown in the embodiment illustrated in FIGS. 4 through 7 are identified by prime numbers.
Base portion, generally 11, 11', includes slot 14, 14'. In practice slot 14, 14' may be an elongated perforation, but it is preferably a slit cut through the sheet constituting the base material. Whereas slot 14 is simply an elongated linear slot, slot 14' includes extensions 15 at each end thereof so that slot 14' assumes the general configuration of a broad "U," thus enclosing tab 16. This "U" has a flat base of a length approximately equal to the width of tongue 20'. Whether slot 14, 14' is a perforation or slit, it is preferred that it terminate in smoothly rounded perforations 17, 17', to lessen tendency to generate a tear and also defining at least a small tab therebetween.
Cover portions, generally 12, 12', include tongue 20, 20' which extend from edge 22, 22' of cover portion 12. In the embodiment illustrated in FIGS. 1 through 3, tongue 20 includes laterally projecting ears 24 which, because of the slightly flexible nature of the plastic material from which the cover 12 is made, flex sufficiently when tongue 20 is pressed through slot 14 to permit passage of tongue 20 through slot 14, but serve as a detent obstructing or hindering removal of tongue 20 in the reverse direction through slot 14. Tongue 20' includes detent 26 which restricts or inhibits withdrawal of cover 12' from base portion 11' through slot 14'.
With specific reference to the embodiments shown in FIGS. 1 through 3, the cover portion, generally 12, includes an elevated transparent crown portion 30, which is surrounded by a first planar portion 32 having skirt 33 peripherally dependent therefrom. At the lower extreme of skirt 33, cover generally 12 extends radially to provide second planar portion 34. It is from the lateral edge 22 of second planar portion 34 that tongue 20 extends. Hole 35 is optionally provided to permit hanging of package 10 for display.
Base or receptacle portion, generally 11, includes a container portion or receptacle 36, for receiving article within sidewalls 37. Sidewalls 37 extend from bottom 38 to the top of collar portion, generally 40, which completely surrounds the opening of receptacle 36. At the top of sidewalls 37, the package extends radially to provide third planar portion, i.e. the top of collar portion 40, from which skirt 43 is peripherally dependent. At the lower extreme of skirt 43, base portion 11 extends radially to provide fourth planar portion 44 in which slit 14 is located. Preferably, hole 45, also in planar portion 44, is provided for hanging the container from a hook (not shown). Naturally, when holes 35, 45 are provided they are positioned opposite one another. Skirt 46 is peripherally dependent from fourth planar portion 44 and terminates at foot 48 which is preferably coplanar with bottom 39. It is preferred that foot 48 include an enlarged tab 50 having perforation 51 therein for hanging the container. It is believed apparent that dependent skirt 46 and foot 48 are entirely optimal structures. When skirt 46 and foot 48 are omitted, fourth planar portion 44 is preferably enlarged to provide tab equivalent to tab 50 shown in FIG. 3 extending from side of container 10 opposite side at which slot 14 is located.
When cover, generally 12, is in the closed position, therefore, first planar portion 32 on cover 12 abuts third planar portion 41 on base 11, and dependent skirt 33 snugly encompasses collar portion 40, thus preventing twisting of cover, generally 12, on base, generally 11. In addition, planar portion 34 generally abuts planar portion 44, except that tongue 20 passes through slot 24. Thus, in the closed position illustrated in FIG. 2 upper surface 53 of tongue 20 bears against the lower surface of planar portion 44. In this closed position the tongue 20 is approximately parallel to the surface 44 having the slit 14 through which the tongue extends.
Dependent skirt 33 includes detents 55 and 56 which seat in depressions 58 and 59 to assist in retaining cover, generally 12, in closed position on base portion, generally 11.
When the cover is moved to the open position, as illustrated in FIG. 3, the tab at the left of slit 14 (as viewed in FIG. 3) is forced upwardly with respect to the tab on the opposite side of the slit and this then forms a resilient stop urging the cover to the open position.
With specific reference to the embodiments illustrated in FIGS. 4 through 7 it is seen that base portion, generally 11' includes opening 61 which snugly receives removable receptacle tray 62. Tray 62 includes radially extending tray flange 63, which rests on base flange 64, and tray detents 66 which prevents tray 62 from flopping out of opening 61 once tray 62 is inserted therein.
Because the use of the novel hinge of this invention permits the container, generally 10' to be fabricated from a base portion, generally 11' which is sturdy opaque material, and cover portion, generally 12' which can be transparent material, it is possible, as a consequence of this invention to provide diagnostic trays such as those illustrated in FIG. 4 in which receptacle tray 62 and cover 12' are thermoformed from transparent plastic sheet thus making the contents (not shown) of tray 62 visible either through cover 12', through the bottom of tray 62, or through opening 61. This permits easy illumination of the contents of trays 62 from above or below and permits visual examination of the contents of tray 62 from above or below. It is preferred that transparent trays 62 be prescored to facilitate counting of items within tray 62.
Each opening 61 and flange 64 is surrounded by elevated portion or ridge 68 having cross section of an inverted "U". Ridge 68 completely surrounds all of the openings 61 flanges 64 and is, in turn, surrounded by first planar portion 69 which is substantially coplanar with flanges 64. Slits 14' are located in planar portion 69. Planar portion 69 is, in turn, substantially surrounded by second ridge 70 from which depends peripheral skirt 72 which, in turn, terminates at foot or base 73.
Cover portion, generally 12', is thermoformed from semirigid transparent plastic material and includes central observation panels 74 which overlie openings 61 and flanges 64. Each panel 74 is surrounded by third ridge 75 which is proportioned and positioned to mate with base ridge 68 when cover, generally 12' is in closed position on base portion 11, as illustrated in FIG. 5. Dependent skirt 77 depends from ridge 75 and terminates preferably with radially extending planar portion 78. Planar portion 78 abuts planar portion 69 and dependent skirt 77 on cover, generally 12, closely surrounds ridge 68 on base, generally 11' to secure cover, generally 12', from twisting when in closed position. Cover, generally 12, is provided with detent 55' which mates with depressions 58' and outer wall of ridge 68 thereby providing snap means for securing cover in closed position.
Thus, when cover, generally 12, is in closed position, as illustrated in FIG. 5, tongue 20' rests inserted through slot 14', thus securing cover, generally 12, to base portion, generally 11. In the closed position shown in FIG. 5, the tongue 20 is approximately parallel to the planar portion 69 having slit 14' therein and the inserted portion of tongue 20' abuts the lower surface of planar portion 69 in the region of slot 14. When the cover is in the open position illustrated in FIG. 6, tongue detent 26 serves to hinder withdrawal of cover generally 12', from slot 14'. In addition, when the cover, generally 12' is pressed in the opening direction, tongue 20' bears against the lower edge of tab 16 (and against the surface 69 at the opposite side of slit 14'), thus forcing tab 16 slightly upward as shown in FIG. 6. The wedging action by which this movement of tab 16 is achieved is effected by reason of the fact that slit 14' is narrower in the width dimension than is the dimension of the thickness of tongue 20' extending through the slit. In the condition illustrated in FIG. 6, skirt 77 in cover 12' rests upon the top of ridge 70, and tab 16 bears against opposed surface of tongue 20' at a point substantially above the level of planar portion 69. It will be appreciated that, in such position, tab 16 serves to prop cover, generally 12', in the open position. Movement of cover, generally 12', in the closing direction towards the position shown in FIG. 5, forces tab 16 downwardly so that in the closed position tab 16 abuts the lower surface of tongue 20'. Thus, by providing slot extensions 15 to form tab 16, means are provided for propping cover, generally 12', in open position. It is also noted that tongue 20' is short enough to permit pivoting of cover, generally 12' to closed position as shown in FIG. 5 without causing tongue 20' to strike interior surface of dependent skirt 72.
ACHIEVEMENT
Thus, in accordance with this invention, thermoformed containers can be manufactured using a first material, for example, 0.030-inch-thick high-impact opaque polystyrene, for the base or receptacle portion, and a second, transparent sheet material, for example, transparent 0.024-inch-thick polyvinyl chloride for the cover portion. The resulting packages are highly useful for display purposes, e.g. for packaging and displaying corsages, baby shoes, and the like. In addition the packages are highly useful for functional reasons as in diagnostic test trays and the like. In addition, the novel two-piece containers can be thermoformed from semirigid plastic sheeting by the well-known vacuum forming techniques. Moreover, the two-piece containers can be assembled by merely inserting tongues situated on the edge of the cover into the slot situated in the base portion thereof. It is manifest that the highly useful articles of this invention are extremely practical, and economical, both from the point of view of use, and from the point of view of manufacture. Hence, it is economically feasible, as a result of this invention to provide disposable diagnostic test trays. The novel hinge of this invention is completely free acting, having no tendency to reclose or pop open.
Thermoformed plastic containers fabricated from a single sheet, and which include a receptacle, or base portion and a cover portion integrally joined by a plastic hinge have serious shortcomings. The "memory" of integral plastic hinges causes them to tend to pop a cover portion open when the cover is closed, or, after the container has been closed for a long period of time, the hinges often tend to close, or partially close the cover when the cover is opened.
Moreover, it is often desirable to provide a container having a base or receptacle portion fabricated from a first material, for example, 0.030 high-impact opaque styrene, and a cover portion manufactured from a second material, for example, transparent 0.024-inch polyvinyl chloride. Such construction is virtually impossible using integral plastic hinge design. However, such multimaterial containers, which would be useful in displaying products such as cosmetics, corsages, baby shoes, and in enclosures requiring transparency for functional reasons, as in diagnostic test trays and the like, must be inexpensively manufactured to achieve widespread use. Moreover, it is highly desirable that the hinge means provided be free acting, that is, having no tendency to reclose or pop open.
Thus, it is an object of this invention to provide a two-piece container thermoformed from semirigid plastic sheet, for example, a container produced by the well-known vacuum forming techniques, which container utilizes a two-piece plastic hinge. It is another object of this invention to provide a plastic hinge which is free acting, that is, having no tendency to reclose, or pop open. It is a further object of this invention to provide plastic hinge construction making it possible to manufacture containers which utilize a first material in the receptacle portion, and a second, transparent material in the cover portion. It is also an object of this invention to provide such plastic containers, which are simply and economically produced.
These and other objects, which will be apparent hereinafter are all achieved in accordance with the invention which is described in detail herein.
SUMMARY OF THE INVENTION
This invention relates to containers manufactured from semirigid, thermoformed plastic sheet material having a two-piece plastic hinge comprising a slit in a base portion of the container, and a tongue in the cover portion, which tongue is constructed to be insertable into the slit, and includes detent means for obstructing withdrawal of the inserted tongue from the slit.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional plan view taken approximately along the line 1-1 of FIG. 2.
FIG. 2 is an elevational cross-sectional view taken approximately along the line 2-2 of FIG. 1.
FIG. 3 is an enlarged fragmentary elevational view taken approximately along the line 2-2 of FIG. 1 showing transposition of cover.
FIG. 4 is a plan view of an alternative embodiment of this invention in which the cover portion is partially shown removed.
FIG. 5 is an elevational cross-sectional view taken approximately along the line 5-5 of FIG. 4.
FIG. 6 is an elevational cross-sectional view also taken along the line 5-5 of FIG. 4 showing the transposition of the lid.
FIG. 7 is an enlarged fragmentary elevational view shown detail of detent means on the hinge tongue of the lid shown in FIG. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Although the following disclosure offered for public dissemination, in return for the grant of a patent, is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose; as it is these that meet the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts are found.
In accordance with this invention plastic packages, generally 10, 10', include a base or receptacle portion, generally 11, 11', and cover or lid portion, generally 12, 12'. Described in this application are two preferred embodiments, one being illustrated in FIGS. 1 through 3, and another being illustrated in FIGS. 5 through 7. Parts in the two embodiments which correspond to each other are given the same number identification in the description which follows, except that parts shown in the embodiment illustrated in FIGS. 4 through 7 are identified by prime numbers.
Base portion, generally 11, 11', includes slot 14, 14'. In practice slot 14, 14' may be an elongated perforation, but it is preferably a slit cut through the sheet constituting the base material. Whereas slot 14 is simply an elongated linear slot, slot 14' includes extensions 15 at each end thereof so that slot 14' assumes the general configuration of a broad "U," thus enclosing tab 16. This "U" has a flat base of a length approximately equal to the width of tongue 20'. Whether slot 14, 14' is a perforation or slit, it is preferred that it terminate in smoothly rounded perforations 17, 17', to lessen tendency to generate a tear and also defining at least a small tab therebetween.
Cover portions, generally 12, 12', include tongue 20, 20' which extend from edge 22, 22' of cover portion 12. In the embodiment illustrated in FIGS. 1 through 3, tongue 20 includes laterally projecting ears 24 which, because of the slightly flexible nature of the plastic material from which the cover 12 is made, flex sufficiently when tongue 20 is pressed through slot 14 to permit passage of tongue 20 through slot 14, but serve as a detent obstructing or hindering removal of tongue 20 in the reverse direction through slot 14. Tongue 20' includes detent 26 which restricts or inhibits withdrawal of cover 12' from base portion 11' through slot 14'.
With specific reference to the embodiments shown in FIGS. 1 through 3, the cover portion, generally 12, includes an elevated transparent crown portion 30, which is surrounded by a first planar portion 32 having skirt 33 peripherally dependent therefrom. At the lower extreme of skirt 33, cover generally 12 extends radially to provide second planar portion 34. It is from the lateral edge 22 of second planar portion 34 that tongue 20 extends. Hole 35 is optionally provided to permit hanging of package 10 for display.
Base or receptacle portion, generally 11, includes a container portion or receptacle 36, for receiving article within sidewalls 37. Sidewalls 37 extend from bottom 38 to the top of collar portion, generally 40, which completely surrounds the opening of receptacle 36. At the top of sidewalls 37, the package extends radially to provide third planar portion, i.e. the top of collar portion 40, from which skirt 43 is peripherally dependent. At the lower extreme of skirt 43, base portion 11 extends radially to provide fourth planar portion 44 in which slit 14 is located. Preferably, hole 45, also in planar portion 44, is provided for hanging the container from a hook (not shown). Naturally, when holes 35, 45 are provided they are positioned opposite one another. Skirt 46 is peripherally dependent from fourth planar portion 44 and terminates at foot 48 which is preferably coplanar with bottom 39. It is preferred that foot 48 include an enlarged tab 50 having perforation 51 therein for hanging the container. It is believed apparent that dependent skirt 46 and foot 48 are entirely optimal structures. When skirt 46 and foot 48 are omitted, fourth planar portion 44 is preferably enlarged to provide tab equivalent to tab 50 shown in FIG. 3 extending from side of container 10 opposite side at which slot 14 is located.
When cover, generally 12, is in the closed position, therefore, first planar portion 32 on cover 12 abuts third planar portion 41 on base 11, and dependent skirt 33 snugly encompasses collar portion 40, thus preventing twisting of cover, generally 12, on base, generally 11. In addition, planar portion 34 generally abuts planar portion 44, except that tongue 20 passes through slot 24. Thus, in the closed position illustrated in FIG. 2 upper surface 53 of tongue 20 bears against the lower surface of planar portion 44. In this closed position the tongue 20 is approximately parallel to the surface 44 having the slit 14 through which the tongue extends.
Dependent skirt 33 includes detents 55 and 56 which seat in depressions 58 and 59 to assist in retaining cover, generally 12, in closed position on base portion, generally 11.
When the cover is moved to the open position, as illustrated in FIG. 3, the tab at the left of slit 14 (as viewed in FIG. 3) is forced upwardly with respect to the tab on the opposite side of the slit and this then forms a resilient stop urging the cover to the open position.
With specific reference to the embodiments illustrated in FIGS. 4 through 7 it is seen that base portion, generally 11' includes opening 61 which snugly receives removable receptacle tray 62. Tray 62 includes radially extending tray flange 63, which rests on base flange 64, and tray detents 66 which prevents tray 62 from flopping out of opening 61 once tray 62 is inserted therein.
Because the use of the novel hinge of this invention permits the container, generally 10' to be fabricated from a base portion, generally 11' which is sturdy opaque material, and cover portion, generally 12' which can be transparent material, it is possible, as a consequence of this invention to provide diagnostic trays such as those illustrated in FIG. 4 in which receptacle tray 62 and cover 12' are thermoformed from transparent plastic sheet thus making the contents (not shown) of tray 62 visible either through cover 12', through the bottom of tray 62, or through opening 61. This permits easy illumination of the contents of trays 62 from above or below and permits visual examination of the contents of tray 62 from above or below. It is preferred that transparent trays 62 be prescored to facilitate counting of items within tray 62.
Each opening 61 and flange 64 is surrounded by elevated portion or ridge 68 having cross section of an inverted "U". Ridge 68 completely surrounds all of the openings 61 flanges 64 and is, in turn, surrounded by first planar portion 69 which is substantially coplanar with flanges 64. Slits 14' are located in planar portion 69. Planar portion 69 is, in turn, substantially surrounded by second ridge 70 from which depends peripheral skirt 72 which, in turn, terminates at foot or base 73.
Cover portion, generally 12', is thermoformed from semirigid transparent plastic material and includes central observation panels 74 which overlie openings 61 and flanges 64. Each panel 74 is surrounded by third ridge 75 which is proportioned and positioned to mate with base ridge 68 when cover, generally 12' is in closed position on base portion 11, as illustrated in FIG. 5. Dependent skirt 77 depends from ridge 75 and terminates preferably with radially extending planar portion 78. Planar portion 78 abuts planar portion 69 and dependent skirt 77 on cover, generally 12, closely surrounds ridge 68 on base, generally 11' to secure cover, generally 12', from twisting when in closed position. Cover, generally 12, is provided with detent 55' which mates with depressions 58' and outer wall of ridge 68 thereby providing snap means for securing cover in closed position.
Thus, when cover, generally 12, is in closed position, as illustrated in FIG. 5, tongue 20' rests inserted through slot 14', thus securing cover, generally 12, to base portion, generally 11. In the closed position shown in FIG. 5, the tongue 20 is approximately parallel to the planar portion 69 having slit 14' therein and the inserted portion of tongue 20' abuts the lower surface of planar portion 69 in the region of slot 14. When the cover is in the open position illustrated in FIG. 6, tongue detent 26 serves to hinder withdrawal of cover generally 12', from slot 14'. In addition, when the cover, generally 12' is pressed in the opening direction, tongue 20' bears against the lower edge of tab 16 (and against the surface 69 at the opposite side of slit 14'), thus forcing tab 16 slightly upward as shown in FIG. 6. The wedging action by which this movement of tab 16 is achieved is effected by reason of the fact that slit 14' is narrower in the width dimension than is the dimension of the thickness of tongue 20' extending through the slit. In the condition illustrated in FIG. 6, skirt 77 in cover 12' rests upon the top of ridge 70, and tab 16 bears against opposed surface of tongue 20' at a point substantially above the level of planar portion 69. It will be appreciated that, in such position, tab 16 serves to prop cover, generally 12', in the open position. Movement of cover, generally 12', in the closing direction towards the position shown in FIG. 5, forces tab 16 downwardly so that in the closed position tab 16 abuts the lower surface of tongue 20'. Thus, by providing slot extensions 15 to form tab 16, means are provided for propping cover, generally 12', in open position. It is also noted that tongue 20' is short enough to permit pivoting of cover, generally 12' to closed position as shown in FIG. 5 without causing tongue 20' to strike interior surface of dependent skirt 72.
ACHIEVEMENT
Thus, in accordance with this invention, thermoformed containers can be manufactured using a first material, for example, 0.030-inch-thick high-impact opaque polystyrene, for the base or receptacle portion, and a second, transparent sheet material, for example, transparent 0.024-inch-thick polyvinyl chloride for the cover portion. The resulting packages are highly useful for display purposes, e.g. for packaging and displaying corsages, baby shoes, and the like. In addition the packages are highly useful for functional reasons as in diagnostic test trays and the like. In addition, the novel two-piece containers can be thermoformed from semirigid plastic sheeting by the well-known vacuum forming techniques. Moreover, the two-piece containers can be assembled by merely inserting tongues situated on the edge of the cover into the slot situated in the base portion thereof. It is manifest that the highly useful articles of this invention are extremely practical, and economical, both from the point of view of use, and from the point of view of manufacture. Hence, it is economically feasible, as a result of this invention to provide disposable diagnostic test trays. The novel hinge of this invention is completely free acting, having no tendency to reclose or pop open.