Abstract:
An irrigation drip tape loop configured so as to largely encircle a plant, and a method for fabricating it. A drip irrigation mat incorporating this drip tape loop so as to provide an irrigated, weed-free, highly-supportive growing environment for both commercial and residential plants as single units, or as rows.

Description:
CROSS-REFERENCE TO RELATED U.S. APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not applicable. 
       REFERENCE TO AN APPENDIX SUBMITTED ON COMPACT DISC 
       [0004]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    This invention relates to drip irrigation and weed suppression for promoting the growth and health of desirable plants. 
         [0007]    More specifically, the invention related to a multi-functional product consistently supplying irrigation fluid to the root zones of desirable plants at low rates and with little runoff by a loop of drip tape while simultaneously suppressing growth of weeds and undesirable plants by an attached synthetic mulch sheet. 
         [0008]    2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98. 
         [0009]    This multi-function product a relatively new concept in plant husbandry, has unique and challenging requirements. For optimum plant growth while avoiding contaminating runoff, very low rates of irrigation flow to the pant are desirable. The flow application needs to be uniform around the plant despite sloping soil topography, which uniformity generally requires significant exit resistance. Also the product preferably has good puncture resistance to prevent damage by thirsty insects. Prior art devices fail to meet these objectives and are less than fully successful. 
         [0010]    Regarding looped irrigators, Mannin (U.S. Pat. No. 6,901,698 B2) describes a flexible soaker hose with a bendable internal conduit allowing the soaker hose to be shaped, for example, to largely encircle a tree. 
         [0011]    Williams (U.S. Pat. No. 4,010,898) described a semi-looped conduit which distributes water around agricultural plants with spray nozzles. 
         [0012]    Mackenzie Nursery Supply Inc. offers a “pressure compensated dribble ring” with a drip emitter attached upstream to limit total flow. (ww.mnsinc.cc/) 
         [0013]    Regarding drip tape, Gilead et al (U.S. Pat. No. 4,413,787) describes a tortuous pressure-reducing pathway between two foils in the absence of a supply hose or tubular conduit. 
         [0014]    Gilead (EP 0293857) devised a straight-line drip tape consisting of a tubular conduit with embossed connecting opposite edges which create a labyrinthine passage for liquid. Included are multiple embossed distribution conduits and first and second labyrinthine sections for pressure reduction. 
         [0015]    Leal-Diaz (U.S. Pat. No. 4,047,995) developed a hose for drip irrigation by imprinting enclosure circuits on overlapped edge sections of the hose to produce water pressure reduction on exiting. 
         [0016]    Regarding irrigation mates, Popa (U.S. Pat. No. 3,302,323) employs plastic sheet-like material which surrounds the plant and has beneath conduits containing orifice openings oriented at 45 degrees relative to fluid flow in the conduits. The conduits are bent in a substantially rectangular configuration and surround the plant. 
         [0017]    Kruer and Thompson (U.S. Pat. No. 6,996,932 B2 and U.S. Pat. No. 6,997,402 B2) provide unitized drip irrigation mats having at least two polymeric material layers selectively bonded together to define fluid-conveying passageways. Also claimed is a drip irrigation mat wherein at least one of the distribution headers is comprised of a flow restricting means. 
       BRIEF SUMMARY OF THE INVENTION 
       [0018]    This invention involves a planar drip tape loop suitable, for example, for drip irrigation of desirable plants. The loop shape of this invention is an improvement over prior art drip tapes which are straight-line strips which do not lie flat when wrapped around the plant. Within the loop are provided primary and secondary flow restrictors leading to emitters. 
         [0019]    Further, it provides designs of low total flow through the design of the primary flow restrictor The secondary flow restrictor provide equal output rates at multiple emitters around the plant regardless of ground slope or unevenness, unlike prior art loops. The drip tape loop is produced by modifying the embossing and laminating methods of prior art straight-line drip tapes. 
         [0020]    The invention also includes a weed-suppressing drip irrigation mat which incorporates this drip tape loop. The planar loop configuration, rather than a strip one edge, is essential for secure attachment to the mat sheet. The drip irrigation mat of the present invention is well-suited for container-grown plants. 
         [0021]    Thus an overall object of this invention is to provide a very-positive growing environment for both commercial and residential plants including drip irrigation and run-off control combined with non-chemical elimination of competing weeds. 
         [0022]    It is a further objective to conserve water and fertilizer by dispensing these at very low rates and only to the root zone of each plant, and further, applying these uniformly despite sloping ground. 
         [0023]    It is a further objective to provide insect bit resistance via the relatively thick-walled embossed drip tape. 
         [0024]    It is still a further overall objective to provide these as a combination of benefits not previously obtainable, and to provide these in an economical product. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0025]      FIG. 1  is a segmented plan view of the drip tape loop of the present invention—which lies flat in the plane of the loop-showing inlet, primary restrictor, header, secondary restrictors, and outlet emitters. 
           [0026]      FIG. 2  is a cross-sectional view of the drip tape loop of  FIG. 1  showing the three flow passageways which lie in the plane of the loop. 
           [0027]      FIG. 3  is a perspective view of the irrigating mat of the present invention, including a cut-away showing the drip tape loop. 
           [0028]      FIG. 4  is an alternative embodiment of the drip tape loop, including slots which decrease the in-lane stiffness and facilitate forming the loop, while simultaneously providing more length for flow passages. 
           [0029]      FIG. 5  illustrates the aspects of a chilling and cutting process for forming the in-plane loops and depositing them on the sheet preparatory to bonding to the mat. 
           [0030]      FIG. 6  shows an alternative embossing concept in which the loop curvature is generated simultaneous with the embossing. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]      FIG. 1  is a segmented plan view of the drip tape loop  10  of the present invention. The inlet tube  11  provides irrigation fluid  19  to the embossed primary restrictor  12  which largely encircles the loop to the multiple-path connector  13 . This connects to the header  14  which circles back around the loop. Multiple connector  15  connect the header to multiple secondary restrictors  16  connected to emitters  17 . Optional tabes  18  provide convenient attachment points. 
         [0032]    Importantly, as an option, the header can be relatively small and/or tortuous, in which case downstream secondary restrictors are shorter/less resistive so that flows at the different emitters are essentially equal. 
         [0033]      FIG. 2  is a cross-section  20  of the drip tape loop of  FIG. 1 . Between the embossed layer  28  and planar layer  29  are formed passageways for the primary restrictor  12   b , header  14   b , and secondary restrictor  16   b . Again, the sizes may be of various proportions depending on the specific design. 
         [0034]    The application of the drip tape loop to irrigate a single plant is the subject of  FIG. 3 . In the drip irrigation mat  20 , the drip tape loop  10   c  essentially encircles the plant for which an expandable plant opening  31  and an installation seam  32  are provided. 
         [0035]    The mat body is an ultra-violet-resistant sheet material sized and shaped to generally cover the area above the pant root zone. It may include appropriate optical properties for reflection or absorption of various wavelengths. Sheet materials may include polymeric film, non-woven or woven fabrics, paper, foam or combinations of these. Irrigation fluid is provided by supply tube  11   c . Optional aeration holes  36  are provided. 
         [0036]    Attachment of the drip tape loop  10   c  to the mat body  34  is facilitated by the tabs  18  which can be attached by intermittent bonds  38  by known techniques including plastic welding, heat sealing, hot melt adhesive, pressure-sensitive adhesive, sewing, laser welding, and the like. In general, durable materials and attachment methods are used to provide for multi-season, multi-year use. 
         [0037]    It will be noted that the drip tape loop  10   c  must lie flat in its plane in order to be securely attached to the mat body  34 . 
         [0038]      FIG. 4  shows an alternative design for the drip tape loop  40  in plan view. Inner notches  41  and outer slits  43  allow for in-plane bending of the drip tape loop  40  without the need for heat or special processing after a straight strip has been embossed, laminated, or slotted. Another benefit of this alternative design is that more space is provided for primary restrictors  12   d  and secondary restrictors  16   d , thus allowing more restrictor length and more flow restriction if desired. Again, distributor  14   d  may be configured to avoid sediment. Connectors  1   d  and emitters  17   d  are unchanged, as is irrigation fluid  19   d.    
         [0039]      FIG. 5  shows a process  50  for achieving in-lane drip tape loops from previous embossed and laminated straight contiguous strips. A straight continuous strip  51  is preheated until soft (process not shown), then wrapped onto a confining slot  52  in the chilled roll  53 . This bends and differentially stretches the outer sections of the soft strip to produce in-plane curvature. The loops are periodically cut (device not show) while, through ports  54 , the vacuum box  55  clamps the strip to prevent loss of in-feed. Completed loops  10   e  are deposited onto continuous sheet  56  for later bonding, thus assembling the drip irrigation mat  30 . 
         [0040]      FIG. 6  shows a perspective view of an alternative process  60  for fabricating the drip tape loops  10   e . Strip plastic stock  61  is fed into a mal/female embossing nip between heated turntable  62  with pattern  63  and heated, synchronized, patterned, conical roller  64  (meshing like bevel gears) to produce the curved strip  65  having embossed pattern  66  in its surface. 
         [0041]    Cover plastic strip  67  is bonded in place by heat and pressure from a smooth conical roller  68 . The embossing patterns of the turntable and rollers are configured to build in the desired in-lane curvature into the completed, curved drip tape  69  simultaneous with producing its embossing and lamination. Take-away and cutting equipment (not shown) cuts this curved drip tape  69  into separate loops  10  (not shown).