Stock material or miscellaneous articles – Display in frame or transparent casing; or diorama including...
Reexamination Certificate
1998-08-26
2001-02-20
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Display in frame or transparent casing; or diorama including...
C428S014000, C428S033000, C428S034000, C428S076000
Reexamination Certificate
active
06190742
ABSTRACT:
FIELD OF THE INVENTION
My present invention relates to a light-permeable plate element having an outer frame and a light transmissive body surrounded by that frame and composed at least in part of a light permeable hollow structure of a thermoplastic synthetic resin, preferably polycarbonate, the hollow structure being comprised of two substantially continuous outer layers bridged by webs or ribs interconnecting the outer layers and defining hollow spaces or compartments between them.
BACKGROUND OF THE INVENTION
Hollow light permeable plastic plates surrounded by a frame can be used in horticulture for green houses and so-called light frames or starting frames as a substitute for window glass which has hitherto been used for such purposes.
It is known, for example, to provide rectangular light permeable plate elements as highly transparent hollow structures of highly transparent polycarbonate within frames of U-section aluminum profiles along the longitudinal and transverse edges of the transparent member and four plastic corner pieces interconnecting the frame limbs in pairs. The frame is thus constituted from four such aluminum profiles or shapes and four plastic elements and the hollow polycarbonate plate within the frame is held in the frame or the frame elements are held on the plate by mechanical clamping.
The polycarbonate plate itself may be fabricated by extrusion and can consist of two mutually parallel spaced apart flat outer layers on thin foils, and a plurality of mutually parallel transversely spaced ribs extending in the extrusion direction and interconnecting the outer layers and spacing them apart. The extruded high-transparency hollow plate of high-transparency polycarbonate, also referred to polycarbonate structural sheets, thus include numerous ribs which extend in the longitudinal direction, are spaced apart transversely to the extrusion direction and define between them the chambers, channels or hollow spaces, also referred to as cells, of the polycarbonate structural sheet. These cells are open at the ends of the polycarbonate structural sheet, which runs transversely to the extrusion direction.
The outer layers and ribs form the cell walls or the walls of the hollow spaces and because of the cellular structure give rise to a high intrinsic stiffness. However, there are problems with attaching the aluminum shapes forming the frame to such structures because of a certain flexibility at the edges of the outer sheets.
High transparency polycarbonate hollow plates are, by comparison with glass plates of equal thickness and size, significantly lighter and practically unbreakable, while having, because of their cellular structure, a high thermal insulation capability and reduced sound transmission.
The flexible cover layer and ribs may have a wall thickness in the range of 0.001 to 0.003 mm and frequently must be connected to aluminum profiles or shapes of U-section and wall thicknesses of 0.5 to 3 mm in forming the frame. The difference in the wall thicknesses and the different mechanical properties of the polycarbonate plate on the one hand and the aluminum frame limb on the other has meant that considerable effort must be made to lock the aluminum frame limbs to the light permeable plate so that it will not loosen in use and as a result of expansion and contraction effects with rising and falling temperature and exposure to solar radiation.
In practice, that has been done by bending fingers or projections from the aluminum frame limbs and so clamping the frame limbs on the light permeable polycarbonate plates that these members can penetrate into the cover layers of the polycarbonate. The members form hooks which can serve to anchor the frame members in place.
It is also known, in providing a mechanical connection between the polycarbonate structural sheet and an aluminum frame limb to press the free ends of the shanks of the metal profile to a smaller distance than the minimum plastic thickness of the polycarbonate plate. The edges of the hollow polycarbonate plate are then compressed between the shanks, causing the elastic ribs to buckle and provide an effective interconnection.
The frame can be assembled from aluminum members and plastic corners which can have pins or studs engaging in the frame limbs and also receiving the edge regions of the hollow polycarbonate plates so that a clamping action between the aluminum limbs and the plate is enhanced by the plastic corner pieces which can project through ribs of the polycarbonate plate for greater security of the mechanical connection.
In conventional plates with such frames, the aluminum U-section limbs enclose the edges of the hollow plates and thus close the open ends thereof, however, without effective sealing of them.
In practice, it is found that condensate can form within the compartments of the place or rain can penetrate into the compartments. Moisture can accumulate and in the presence of air, microscopic spores can grow which can reduce the transparency of the plate by forming dark colored deposits. Such algae and other biological growths cannot be removed without damaging the plate and without removing the frame members. In practice, it is found that once the frame member is removed, its replacement is not possible in a convenient manner.
OBJECTS OP THE INVENTION
It is the principal object of the present invention to provide a light-permeable plate for the aforedescribed purposes whereby the drawbacks outlined above can be obviated.
Another object of the invention is to provide a framed plate of the type described which is less in danger of suffering condensate formation or discoloration from microorganism growth than earlier plate systems.
SUMMARY OF THE INVENTION
These objects and others which will become apparent hereinafter are attained, in accordance with the present invention in a light permeable plate element having an external frame, a light permeable plate within this frame and surrounded thereby along its entire perimeter and composed of a thermoplastic synthetic resin, such as a polycarbonate, the light permeable plate being formed at least in part by two cover layers interconnected by respective ribs and defining compartments between them. According to the invention, a portion of the entire periphery of the plate is formed with a one piece synthetic resin frame composed of a plastic whose melting point is lower than that of the hollow plate and which seals the edge of the hollow plate and especially the open ends of the chambers.
In other words the light permeable plate has a reinforced edge in which the compartments are sealed as will be described in greater detail hereinafter.
More specifically, these objects are attained in accordance with the invention in a light permeable structure in which the outer frame of the light permeable hollow member surrounds the entire periphery of the latter which at least in part is a plate of high-transparency thermoplastic synthetic resin, for example, a polycarbonate. The plate is formed along at least a portion of its entire periphery with a one piece bonded synthetic resin frame which is composed of a synthetic resin whose melting point is lower than that of the hollow plate and is so bonded to the edge thereof that it closes and seals the cells or chambers of the latter.
The assembly according to the invention is thus composed entirely of plastic and is a composite element in which the plastic frame is permanently joined to the plastic hollow body. The frame is not only bonded to the plate but also closes and seals the cellular plate so that during use there is no possibility of microscopic spores penetrating into the cell interiors and, further, no possibility for nutrients to enter the cells and serve as a basis for multiplication of such spores or microorganisms there within.
According to a further feature of the invention, in the edge regions, in part to close and seal the chambers, the light-permeable hollow plate is compressed along the edge region and the synthetic resin frame is injection molded directly along the compressed edge of
Bahta Abraham
Dubno Herbert
Jones Deborah
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