Food tray with integral cover
United States Patent 3876130

A foamed plastic food tray having a cover of the same material hinged to one side of the tray is formed with a simple, secure latch constituted by a portion of a strengthening rim about the periphery of the tray and a slot in a depressed flute of a skirt at the front of the cover.

Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
International Classes:
B65D1/36; (IPC1-7): B65D1/00; B65D5/66
Field of Search:
229/2.5,29M,44R,44M 220
View Patent Images:
US Patent References:
3786982THERMOFORMED SNAP CLOSURES1974-01-22Rakes et al.
3511433UNITARY FOAM SHEET CONTAINER1970-05-12Andrews et al.

Primary Examiner:
Christian, Leonard D.
Attorney, Agent or Firm:
Huggett C. A.
I claim

1. In a package of the class described:


The invention is concerned with a preformed package of general utility but particularly adapted to enclosure of prepared foods. Illustrative examples herein include packaging of complete meals and of hot sandwiches such as hamburgers or other fillings of sandwiches utilizing buns.

Prepackaged prepared foods are presently available in a great variety of contained food products and nature of packages. Frozen foods, either raw or prepared, must be enclosed by means which inhibit transfer of gases and vapors, for example to prevent excessive loss of moisture resulting in "freezer burn." It will be recognized from the description hereinafter that the package of this invention is not inherently vapor-tight, in fact, for some purposes herein discussed, it is desirable to afford a substantial measure of ventilation. Such packages may be enclosed by bags, coated wrappers or the like known in the art, if freezing is desired.

The invention is, accordingly, more in the field of permeable or ventilated packaging which may be optionally wrapped for freezer storage. Such packages may contain sandwiches, such as those on a bun in which the filling is any one of a variety of tasty meats and other foods, e.g., hamburgers, cheeseburgers, barbecued beef or pork, chicken, fish, sliced beef, etc. Depending on the election of the consumer, the so packaged food may be consumed immediately on the sales premises (where permitted); carried to automobile, home or picnic grounds for consumption after a relatively short interval; stored under refrigeration for consumption within a few days; or frozen for storage over a longer period of time to be consumed at a time suiting the convenience or emergency of the consumer.

More or less complete meals are also prepared in package form, e.g., the sidely sold frozen packages commonly referred to as "TV Dinners" which may be heated in the metal trays of the package when desired. More recently, institutional and industrial food suppliers have made use of disposable compartmented serving containers in which each of several foods intended for consumption at the same meal by one person is filled into a separate compartment of the tray or dish-like container. These are convenient for dispensing lunches and other meals at schools, industrial cafeterias, and other similar facilities. The technique is also applicable to use in galleys of planes, trains and watercraft, particularly sight-seeing boats.

Some of such packages use metal trays or dishes, generally aluminum, of light gauge and low cost, suitable for discard after consumption of the contained food. Such packages are heated, when desired, in radiant heat ovens over a period of time suitably long for raising the interior of the food to a desired elevated temperature without application of such intense heat radiation as to adversely affect the surface of the food. These metal packages are not suited to rapid heating in microwave ovens.

Other known food packages are bags of metal foil, paper, plastic film and the like. These are very effective for "carry-out" foods, such as hamburgers. They provide essentially no protection of physical integrity of the contained food and must be handled with care to avoid abrasion, crushing or other mechanical impairment of surface, form and arrangement of elements of the food, all of which are detrimental to the original appetizing appearance of the food, if not of its nutritive value.

Plates and other dishes of greater depth are often formed of pulp or plastic. A more recent development, described in U.S. Pat. No. 3,684,633, Haase, provides a variety of tableware which is thermoformed of foamed plastic having a layer of plastic film on at least one surface. The technology so described is applicable to formation of plates, bowls, cups, saucers, in fact of tableware generally. Covers suitable for such vessels are described in copending application of N.D. Commisso, Ser. No. 271,864, filed July 14, 1972.

The rigid dishes of plastic, like those of china, glass etc., intended for repeated reuse may be covered by a sheet of protective material, such as foil, paper or plastic film to protect the contents from contamination. Such fragile elements leave the contents subject to physical damage or disarrangement, though to a lesser extent than the three-dimensional insecurity found with bags, as above described. Relatively rigid covers for permanent or disposable vessels are available in a variety of materials. These separate covers are inconvenient at best. A greater disadvantage is found when it is attempted to use separate vessels and covers in the preparation and dispensing of prepared foods on a large scale, as practiced by roadside "hamburger shops." In such environment, the use of separate vessels and covers is grossly wasteful of time in requiring that the packager draw from two separate sources of supply of packaging elements.

Food packages have been made by concurrent thermoforming of a lid and tray portion joined by an integral hinge and characterized by matching surfaces. These have been provided with such fasteners as a tongue projecting from one member engageable by an opening cut into the other whereby closure is effected.


The invention provides a packaging system uniquely suited to the needs of dispensers of food in large volume. This and other desirable objectives are achieved by an integral food-containing vessel and cover therefor joined by a linear hinge portion. Both vessel and cover are of generally similar outline in cross-section. The vessel is provided at its upper, open edge with a flange extending outwardly of the vessel in a plane generally perpendicular to the central axis of the vessel. The flange serves two important purposes. The flange, together with the side wall of the vessel, provides a strengthening structure because lateral pressures against the side of the vessel will be strongly resisted by this web in a plane parallel to the applied stress. The flange also serves as a protection against contamination of the contents of the closed package in a manner presently to be described.

The cover of the package according to this invention is also provided with a circumferential flange which strengthens the cover, and hence the package as a whole, in a manner analogous to the effect of the flange about the vessel portion as described above. The flange about the cover is provided with a dependent skirt at the outer edge of the cover flange, which skirt extends about those portions other than the hinge. By this arrangement, two flanges in contact provide a means for restricted ventilation which avoids contamination while permitting enough flow of air to avoid development of a "soggy" condition. The skirt about the flange of the cover extends over the joint between the flanges of the vessel and cover thus inhibiting flow of suspended solid contaminants present in the atmosphere to the interior of the package. It will be apparent that two facing flanges provide a channel of air flow of high pressure drop, insuring that rate of air flow shall be low. The skirt about the joint (depending from the upper, or cover, flange) assures that such slow air flow shall cause dropout of solid contaminants at the exterior of the package.

The security of closure in the package of this invention is provided by a positive mechanical latch as compared with the friction closure arrangement of other techniques for closure. A flute extending across the skirt at the front of the cover is provided with an opening adapted to receive the flange about the vessel. This arrangement affords a mechanical abutment type of latch and avoids the angular corners and unsupported flaps of other types of closure.

These and other objects and advantages will be apparent from consideration of the annexed drawings, taken with the description thereof below.


FIG. 1 is a plan view of a package according to the invention in open position;

FIG. 2 is a view of the same package as in FIG. 1, shown in elevation;

FIG. 3 is an elevation view of the same package as FIGS. 1 and 2, but shown in closed position and illustrating the recessed character of the latch;

FIG. 4 is a fragmentary section through the latch taken on line 4--4 of FIG. 3;

FIG. 4A is an enlarged section of the latch shown in FIG. 4;

FIG. 5 is a fagmentary plan view, similar in nature to that of FIG. 1, of a modified form of the invention providing compartments in the vessel for packaging a complete meal;

FIG. 5A is a fragmentary section on line A--A of FIG. 5;

FIG. 6 is a plan view, in open position, of a package having superficial resemblance to the package of this invention but with a different latch and lacking the skirt;

FIG. 7 is a view in elevation of the closed package illustrated by FIG. 6; and

FIG. 8 is a fragmentary section on line 8--8 of FIG. 7.

FIGS. 6, 7 and 8 are included for comparison purposes to demonstrate the advantages of the invention. The structure illustrated by FIGS. 6, 7 and 8 is not intended to be claimed in this application.


It is a principal object of the invention to provide a package, particularly for foods, which is readily fabricated on automatic, high-speed machinery of low cost materials having substantial heat insulating qualities. It is a further object that the open package, as supplied for filling and closing shall be nestable in the sense that a large number of empty packages can be stacked together, each within the cavities of an adjacent carton, such that the volume occupied is very little more than the sum of the thicknesses of walls of the packages. Such nesting results in najor economies in shipping and storage. It is a further object that the empty packages be readily denested; that is, the empty packages in a stack should be capable of easy, rapid and uniformly smooth removal from the stack at either end for convenience and low cost of the filling and closing operation.

Further objects contemplate easy latching of the package and a secure mechanical detent when latched. It is further contemplated that the package shall be easily opened when desired and that it be capable of reclosing and reopening many times without substantially impairing security of closure.

The invention has, as additional objects, a rugged structure resistant to mechanical damage and capable of protecting the contents of the closed package against air-borne contamination without major inhibition of ventilation; it being understood that the package may be totally enclosed by films or like which are impervious to gases and vapors. A still further object is of particular importance when the package is so enclosed. That further object is provision of a package free of sharp corners and spurs on its exterior to avoid damage to the carton by "catching on" fabrics or projecting elements and to avoid danger of puncture to enclosing films.

The achievement of all these objectives simultaneously requires a particular combination of structural elements as provided by this invention. Constraints on available options are imposed by such features as the need for production on high speed molding machinery to provide for manufacture at an acceptable cost.

Some features of the present package are also present in the packages described in my copending applications for design patents Ser. Nos. 342,224 and 342,240, both filed Mar. 16, 1973.

Typical materials of construction which will provide the desired heat insulation and strength are foamed resins, such as foamed polystyrene, and pulp. The former is supplied as a web of foamed resin to a thermoformer in which the web is heated to a temperature high enough to permit reformation and drawing operations and is then pressed between cooled matching molds to the desired form. Pulp articles are formed from a suspension of paper fibers in water supplied to a screen conforming to the desired shape. A vacuum applied to the side of the screen opposite to the supply of water suspension causes the fibers to felt on the screen in the desired form. Upon drying, the finished product is removed from the screen.

Both forming operations here briefly described require that the form of the article be such that it is readily stripped at high speed from the forming element with a high degree of assurance. Faulty stripping of a single article, even to the extent of misalignment, results in jamming of the machine and costly shut-down to clear the jam. For that reason, surfaces of the formed article must be sloped such that stripping involves merely release from the surface of the forming element, as contrasted with sliding friction between surfaces parallel to the direction of withdrawal. There should be no undercuts, unless costly forming elements having retractable parts are provided.

These limitations on structure arising from the manner of manufacture are satisfied and the other objects are fulfilled by packages having features shown in the annexed drawings, wherein like parts are referred to by the same reference numerals.

A very useful form of the invention is embodied in the "hamburger package" shown in FIGS. 1, 2, 3 and 4. This structure is adapted for dispensing of the well known hamburger constituted by ground beef in a bun and is subject to wide variation by addition of cheese, vegetables, condiments and the like. The package comprises a vessel 10 and cover 11. These elements are formed simultaneously and integral with each other as shown. Along the line of division between the vessel 10 and cover 11 means are provided to assure that, on closing, the fold line will be in a predetermined hinge area to assure registry of vessel and cover. In the embodiment shown, the hinge line is defined by a compressed hinge line 12 in the foam, pulp or other material of construction.

The vessel 10 is of generally rectangular shape in horizontal cross-section with rounded corners and curved, bulging sides formed by the side walls 13 which slope outwardly in rising from the bottom 14 to a horizontal flange 15. The flange 15, formed integrally with the vessel 10, extends across the front and along the two sides of the vessel 10 and is preferably continued across the back in a manner to space the vessel 10 from the hinge line 12. For convenience in removing the contents, the vessel 10 may be provided with recesses 16 at one or both rear corners, thus enabling the consumer to insert a finger or fingers behind and under the contents of the package.

The cover 11 comprises a top wall 17, side walls 18 and flange 19 generally similar to the corresponding elements of the vessel 10 in size and configuration. At the front and along the sides of the flange 19 is a skirt 20, which, in the closed position of the package depends from the flange 19 to overlie and protect the abutment of flanges 15 and 19 as shown in FIGS. 3 and 4. As best seen in FIGS. 1 and 2, the edge of skirt 20 converges toward the flange 19 from front to back and is faired into the surface of flange 19 at the rear of cover 11.

At the front of the package (remote from the hinge 12) the wall forming skirt 20 is depressed to form a flute 21 deep enough to intersect flange 15 of vessel 10. A slot 22 is punched through the flute at this area of intersection such that, on closure of the package, the adjacent portion of flange 15 is received in slot 22 for positive latch of the package without the appearance of elements projecting substantially beyond the pleasingly curved protecting surfaces of the package. This feature will be clearly apparent on study of the fragmentary section of FIG. 4.

As seen in FIG. 5, the invention may be applied to a variety of package configurations and purposes. In the embodiment of FIG. 5, the vessel is more sharply rectangular than in FIG. 1, though it is still preferred that corners be rounded as shown. The FIG. 5 package is adapted to contain a complete meal and, for that purpose, the vessel 10 is divided into three compartments by partitions 23 and 24 molded into the bottom 14, as by forming a double wall at each partition area. See FIG. 5A.

Referring now to FIGS. 6, 7 and 8, it will be immediately apparent that the fluted skirt arrangement of this invention is superior in appearance, security of closure, protection against contamination, and ease of handling as compared with a closure which is feasible for flanged cover and vessel elements without the skirt. As best seen in FIG. 6, this comparative package comprises, as does the package of the invention, vessel 10 and cover 11 having, respectively, bottom and top walls 14 and 17; side walls 13 and 18; and flanges 15 and 19. The closure arrangement is constituted by a tongue 25 formed by cutting the cover flange 19 and an open ended slot 26 cut into the vessel flange 15. On closure, the tongue 25 is drawn down into slot 26 to frictionally engage the sides of slot 26 in the manner shown by FIG. 7.

It will be seen that engagement of the closure in the package of FIGS. 6, 7 and 8 requires a separate operation in addition to that of rotating the cover 11 above the hinge line until the flanges 15 and 19 abut each other. The tongue 25 must be displaced from its position in the flange 19 and manually brought down through the slot 26. After engagement of the closure the package has only frictional forces to retain its closed position. By contrast, the positive latch of this invention automatically engages as the package is closed and the sloping inner wall of flute 21 rides over flange 15 until the latter enters slot 22 for positive locking. In addition, skirt 20 functions to protect against accidental contamination while permitting escape of water vapor and the like, as from a hot hamburger and thus avoids development of a soggy condition of the contained food.

The package of this invention may be utilized in a variety of different ways. Having regard only to the hamburger package of FIGS. 1, 2 and 3, it may be applied in dispensing products at roadside establishments by placing freshly cooked hamburgers in individual packages as cooking is completed and placing a supply at hand for prompt sale. The packaged food is adapted to be eaten at once or at a future time. Freshness will be retained in driving a short distance, as to a picnic ground. If longer delay is contemplated, the packaged product is easily reheated by a microwave oven without removal of the food from the package until heating is complete. Such microwave reconstitution of previously prepared (fully cooked) frozen food is a system in which the invention offers important advantages. This technique is not restricted to use by individual consumers. For example, hospitals find it efficient to freeze prepared foods and reconstitute the meal by microwave heating near the rooms of patients. In this manner, the food is served hot without being maintained in a heated cart for periods which result in loss of flavor. Many vessels available for the purpose have pronounced tendency to "pop" open in the microwave oven. The positive mechanical latch of the food container provided by this invention avoids that difficulty. Alternatively, sandwiches and other foods intended for consumption hot may be so packaged in the raw state (preserved in a freezer if desired) and cooked to taste when the occasion arises.