Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation-in-part of our U.S. patent application Ser. No. 09/084,864, filed May 26, 1998, now U.S. Pat. No. 6,022,311, and incorporated herein by reference. 
     Priority of U.S. Provisional Patent Application Ser. No. 60/068,035, filed Dec. 18, 1997, incorporated herein by reference, is hereby claimed. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable 
     REFERENCE TO A “MICROFICHE APPENDIX” 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to hearing aids and more particularly to an improved hearing aid, its method of manufacture and an improved method of compensating for hearing loss. More particularly, the present invention provides an improved method and apparatus for compensating for hearing loss that uses a construction combining a rigid mounting member (for example, a face plate) with a soft polymeric body that is joined to the mounting member and which encapsulates some of the electronic hearing aid components of the apparatus, the soft polymeric body being sized and shaped to conform to the user&#39;s ear canal during use. It may be possible to use a soft polymeric material as the face plate. 
     2. General Background of the Invention 
     The hearing industry has realized major strides in the development of high-fidelity, high-performance products, the most recent of which is digital signal processing technology. Hearing care professionals expected those advancements to solve the shortcomings of traditional amplification, and to push the market forward. Those expectations have not been fully realized. While these developments have solved many of the problems associated with traditional electronic design and steadily gained market share, they have not fostered overall market growth. 
     The issues of early acoustic feedback, less than optimum fidelity and intermodulation of the frequency response cannot be completely resolved by electronic manipulation of the signal by either analog or digital means. 
     Historically, custom-molded ear worn hearing instruments have been limited to an “acrylic pour” process as the means of the construction. With the advent of miniaturization and technological advancement of computer chip programming, the ear-worn instruments have become smaller and are positioned into the bony portion of the ear canal, commonly referred to as “deep insertion technology”. 
     Developments outside the hearing industry have culminated in a new level of micro-miniaturization of electronic components for industry applications. Consequently, advanced signal processing can be housed in less space than was required for traditional electro-acoustic components. 
     With the development of programmable hearing aids, using either analog or digital signal processing, custom electronic design has shifted from the manufacturing level to the clinical level. The clinician can now customize the electro-acoustic response via software. It is no longer necessary for the device to be returned to the manufacturer for hardware changes to arrive at the desired electro-acoustic response. However, it is still often necessary to return the device for shell modifications. 
     In direct contrast to electronic advances within the industry, little or no advancement has been realized in custom prosthetic design. Since the late 1960&#39;s, when the custom in-the-ear hearing aid was developed, materials and construction techniques remained virtually unchanged. These materials and techniques were adopted from the dental industry, whereby the customized housing-commonly called a “shell” was constructed using acrylic of 90 point Durometer Hardness Shore D. This construction process provided the structure and the strength of material necessary to protect the electronics. 
     At the time the acrylic shell was developed, hearing instruments were worn in the relatively forgiving cartilaginous portion of the ear canal. Micro-miniaturization of electronic components, combined with increased consumer demand for a cosmetically acceptable device, has shifted the placement of the hearing aid toward the bony portion of the ear canal. 
     The bony portion of the canal is extremely sensitive and intolerant of an acrylic shell when that shell is over sized due to standard waxing procedures or is in contact with the canal wall beyond the second anatomical bend. Rigid acrylic that does not compress must pivot in reaction to jaw or head movement, thereby changing the direction of the receiver yielding a distorted acoustic response. In addition, the pivot action causes displacement of the device resulting in unwanted acoustic feedback. This problem has necessitated countless shell modifications, thereby compromising the precision approach of the original dental technology. Many such devices require some modification by the manufacturer. Most manufacturers can expect a high percentage of returns for modification or repair within the first year. Consequently, CIC (completely in canal) shell design has been reduced to more of a craft than a science. Although the recent introduction of the ultra-violet curing process has produced a stronger, thinner shell, the overall Shore Hardness remained unchanged. 
     The current trend for custom hearing aid placement is to position the instrument toward the bony portion of the ear canal. The ear canal can be defined as the area extending from the concha to the tympanic membrane. It is important to note that the structure of this canal consists of elastic cartilage laterally, and porous bone medially. The cartilaginous portion constitutes the outer one third of the ear canal. The medial two-thirds of the ear canal is osseous or bony. The skin of the osseous canal, measuring only about 0.2 mm in thickness, is much thinner than that of the cartilaginous canal, which is 0.5 to 1 mm in thickness. The difference in thickness directly corresponds to the presence of apocrine (ceruminous) and sebaceous glands found only in the fibrocartilaginous area of the canal. Thus, this thin-skinned thinly-lined area of the bony canal is extremely sensitive to any hard foreign body, such as an acrylic hearing instrument. 
     Exacerbating the issue of placement of a hard foreign body into the osseous area of the ear canal is the ear canal&#39;s dynamic nature. It is geometrically altered by temporomandibular joint action and by changes in head position. This causes elliptical elongation (widening) of the ear canal. These alterations in canal shape vary widely from person to person. Canal motion makes it very difficult to achieve a comfortable, true acoustic seal with hard acrylic material. When the instrument is displaced by mandibular motion, a leakage or “slit leak” creates an open loop between the receiver and the microphone and relates directly to an electroacoustic distortion commonly known as feedback. Peripheral acoustic leakage is a complex resonator made up of many transient resonant cavities. These cavities are transient because they change with jaw motion as a function of time, resulting in impedance changes in the ear canal. These transients compromise the electroacoustic performance. 
     The properties of hard acrylic have limitations that require modification to the hard shell exterior to accommodate anatomical variants and the dynamic nature of the ear canal. The shell must be buffed and polished until comfort is acceptable. The peripheral acoustic leakage caused by these modifications results in acoustic feedback before sufficient amplification can be attained. 
     Hollow shells used in today&#39;s hearing aid designs create internal or mechanical feedback pathways unique to each device. The resulting feedback requires electronic modifications to “tweak” the product to a compromised performance or a “pseudo-perfection”. With the industry&#39;s efforts to facilitate the fine-tuning of hearing instruments for desired acoustic performance, programmable devices were developed. The intent was to reduce the degree of compromise, but by their improved frequency spectrum the incidence of feedback was heightened. As a result, the industry still falls well short of an audiological optimum. 
     A few manufacturers have attempted all-soft, hollow shells as alternatives to acrylic, hollow shells. Unfortunately, soft vinyl materials shrink, discolor, and harden after a relatively short period of wear. Polyurethane has proven to provide a better acoustic seal than polyvinyl, but has an even shorter wear life (approximately three months). Silicones have a long wear life but are difficult to bond with plastics such as acrylic, a necessary process for the construction of custom hearing instruments. To date, acrylic has proven to be the only material with long term structural integrity. The fact remains, however, that the entire ear is a dynamic acoustic environment and is ill-served by a rigid material such as acrylic. Also, the acrylic hearing aids typically need to be returned to the manufacturer for major shell modifications. 
     The following references are all incorporated herein by reference: 
     U.S. Pat. Nos.: 4,051,330; 4,375,016; 4,607,720; 4,716,985; 4,811,402; 4,870,688; 4,880,076; 4,937,876; 5,002,151; 5,068,902; 5,185,802; 5,201,007; 5,259,032; 5,530,763; 5,430,801; 5,500,902; and 5,659,621. 
     Also of interest and incorporated herein by reference are published Japanese patent application no. JA61-238198, the articles from December 1997 Journal of American Academy of Audiology, and Staab, Wayne J. and Barry Finlay, “A fitting rationale for deep fitting canal hearing instruments”, Hearing Instruments, Vol. 42, No. 1, 1991, pp. 7-10, 48. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a method and material for the construction of a soft hearing instrument that is solid (i.e. eliminates void spaces). This instrument includes a soft body portion that is truly soft, comprising an elastomer of about 3 to 55 durometer Shore A and preferably 10-35 durometer Shore A. This product is unique in that it is solid, with the electronic components actually encapsulated or embedded within the soft fill material. The fill material can be a Dow Corning® MDX-4-4210 silicone or a silicone polymer distributed by Factor II, Inc. of Lakeside, Ariz., designated as product name 588A, 588B, 588V. 
     The present invention provides a method that can replace traditional acrylic shell construction. Unlike the shell construction process, the ear impression is not modified, built up, or waxed. With the elimination of these steps, a more faithful reproduction of the ear impression is accomplished. With the present invention, the manufacturer should be able to produce a hearing aid body which will not need to be returned as frequently for modification as with present hard acrylic hearing aid bodies. 
     The apparatus of the present invention is virtually impervious to the discoloration, cracking, and hardening experienced with polyvinyls and polyurethanes. 
     The hearing aid of the present invention provides a greater range of gain before feedback occurs. 
     The outer surface of the body of the present invention is preferably non-absorbent and virtually impervious to cerumen. 
     As used herein, “in the ear hearing aids” includes all hearing aids which have all of the electronics positioned in the ear, and thus includes hearing aid styles ranging from full concha to CIC (completely in the canal) hearing aid styles. 
     The preferred embodiment of the present invention shown in the drawings is a CIC hearing aid style. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
     FIG. 1 is a sectional elevational view of a user&#39;s hearing area to show the anatomy thereof; 
     FIG. 2 is a sectional elevational view of a user&#39;s ear canal showing placement of a dam and mold material as part of the method of the present invention; 
     FIG. 3 is a perspective view of the form portion used with the preferred method of the present invention; 
     FIG. 4 is a perspective view illustrating shaping of the form as part of the method of the present invention; 
     FIG. 5 is a perspective view illustrating a dipping of the form into a vessel carrying material for making the female mould as part of the method of the present invention; 
     FIG. 6 is a perspective view illustrating a coating of the form with the female mould as part of the method of the present invention; 
     FIG. 7 is a partial elevational view of the preferred embodiment of the apparatus of the present invention illustrating the mounting member and the plurality of the electronic hearing aid components; 
     FIG. 7A is a cross-sectional view taken along the line  7 A— 7 A in FIG. 7; 
     FIG. 7B is a partial view showing the portion indicated in FIG. 7 as  7 B; 
     FIG. 8 is a elevational view of the lateral side of the mounting member taken along lines  8 — 8  of FIG. 7; 
     FIG. 9 is a perspective view illustrating the method step of joining the female mould to the mounting member at the medial side thereof; 
     FIG. 10 is a perspective view of the preferred embodiment of the apparatus of the present invention and showing the method of the present invention after the joining of the female mould and mounting member; 
     FIG. 11 is a perspective view illustrating the method step of adding filler material to the interior of the female mould and encapsulating electronic hearing aid component portions of the apparatus; 
     FIG. 12 is a perspective view illustrating removal of the female mould after the filler material has set and encapsulating the electronic hearing aid components; 
     FIG. 13 is a perspective of the preferred embodiment of the apparatus of the present invention and the method of the present invention illustrating removal of excess plate and tube material from the mounting member; 
     FIG. 14 is a perspective view of the preferred embodiment of the apparatus of the present invention; 
     FIG. 15 is an elevational view of the preferred embodiment of the apparatus of the present invention; 
     FIG. 16 is an end view of the preferred embodiment of the apparatus of the present invention taken along lines  16 — 16  of FIG. 15; 
     FIG. 17 is a top view of the preferred embodiment of the apparatus of the present invention taken along lines  17 — 17  of FIG. 15; 
     FIG. 18 is a graphical representation of a comparison of real ear occlusion gain for the present invention versus a hard shell, hollow-type instrument; and 
     FIG. 19 is a graphical representation showing a comparison of real ear aided gain obtained before acoustic feedback, comparing the present invention with a hard shell, hollow-type instrument. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 and 2 show a user&#39;s ear  1  and anatomical parts of the ear. In FIG. 1 there can be seen the external auditory canal  2 , ear canal wall  3 , auricle  4 , isthmus  5 , tympanic membrane  6 , middle ear  7  and inner ear  8 . In FIG. 2 a dam  9  such as a cotton dam or Otoblock® dam is positioned at the isthmus  5 . The dam  9  is used as a first step of the method of the present invention wherein a form portion  11  or impression material is formed of silicone, methylmethacrylate or algenate. The form  11  is formed in between dam  9  and auricle  4  as shown in FIG.  2 . 
     During the method step of making the form  11 , the form  11  conforms to all of the curvatures of the ear canal  3  so that an accurate form  11  is provided for making a female mould. 
     The female mould  15  is shown in FIGS. 5,  6  and  9 - 12 . In FIGS. 3 and 4, the form  11  is shown after being removed from the ear  1  (FIG. 3) and during a cutting of the form  11  using knives  12  to cut excess material that is designated as  13 ,  14  in FIG.  4 . The form  11  is separated from excess material  13  and  14  at sagittal plane  16 . After the form  11  is trimmed in FIG. 4, a technician&#39;s hand  18  dips the form  11  into vessel  17  as schematically indicated by the arrow  20 . The vessel  17  includes a liquid material  21  that cures at room temperature such as room temperature curing methacrylate (sold by Esschem). It is preferable to use a clear material  21  in the method step shown in FIG.  5 . 
     In FIG. 6, the technician&#39;s hand  18  has removed the form  11  so that a coating of material  21  cures at room temperature (or with an ultraviolet light process) to form female mould  15  on form  11 . After it cures, the female mould  15  is removed from form  11  for use as shown in FIGS. 9 and 10 during assembly of the apparatus  10  of the present invention. The mould  15  can be a few millimeters in wall thickness (typically 1-3 mm). A number of electronic components are mounted to a mounting member  22  prior to use of the female mould  15 . Mounting member  22  provides a medial side  23  and lateral side  24 . The medial side  23  supports a number of hearing aid electronic components as shown in FIGS. 7,  9 , and  10 . In FIG. 7, these hearing aid electronic components include commercially available hearing aid components including a microphone  25 , volume control, battery, socket or plug  28  for communicating with a computer, chip or micro processor circuit, wiring harness  38 , input capacitor, amplifier  34 , receiver/speaker  35 , and receiver tube  37 . 
     In FIG. 8, the lateral side  24  of mounting member  22  shows the microphone  25 , battery compartment  26 , volume control  27 , programming socket  28  for communicating with a computer, silicone plug  54  (see FIG.  9 ), and vent opening  29  that communicates with vent tube  30  (see FIG.  10 ). In FIG. 9, battery  31  is shown housed in battery compartment  26 . The electronic hearing aid components also include a battery terminal  32 , voltage regulating capacitor  33  (see FIG.  15 ), amplifier/microprocessor  34 , receiver  35  having speaker port  36 , and receiver tube  37 . A wiring harness  38  includes a plurality of wires that connect to various electronic components of the hearing aid device together. The wiring harness  38  includes a length of wires  39  that are arranged in an S or multiple curved pattern as shown in FIG.  7 . This “S loop” configuration of wires  39  helps protect the integrity of the electronics when the hearing aid apparatus  10  is flexed as occurs during use because of its soft nature. Further, the S-loop wires  39  are preferably a 44 gauge five strand Litz wire (or magnet wire). The length of the S-loop wires  39  is preferably at least 1.5 times the distance between the terminals to the receiver (or microprocessor)  35  and the amplifier  34  terminals. These “S-Loop” wires  39  prevent excess tension or compression from being transmitted to the electronics during use (e.g. flexing, elongation, compression of hearing aid  10 ). 
     Vent tube  30  is anchored to the mounting member  22  and preferably also to one of the electronic components at a position spaced away from the mounting member  22 . Vent tube  30  acts as a tensile load carrying member that carries tension so that the wiring harness  38  is substantially free of a tensile load that could damage the wiring harness  38 . Also, when vent tube  30  is anchored to one of the electronic components (such as receiver  35 ) at a position spaced away from the mounting member  22 , it may provide enough strain relief that it would not be necessary to coil wires  39  as shown (they could be straight instead). 
     Something else could be used as a load carrying member, in place of vent tube  30  (in which case vent tube  30  would not necessarily be anchored to one of the electronic components (such as receiver  35 )) at a position spaced away from the mounting member  22 . For example, a monofilament cantilever  55  can be used to carry tension so that tension is not transmitted to wiring harness  38 . In FIGS. 7,  7 A, and  7 B the link  55  is anchored to plate  22  at opening  56 . Fastener  57  affixes to receiver tube  37  at large opening  59 . Monofilament cantilever  55  attaches to fastener  57  at smaller diameter opening  58 . Alternatively, vent tube  30  could be manufactured of a tensile material that carries tensile load. The vent tube  30  would then be anchored to plate  22  and fastener  57  as the tensile member. 
     The monofilament cantilever  55  provides longitudinal stability to the body. It minimizes longitudinal displacement (stretching as well as compression) and thus acts as a longitudinal stabilizer (a longitudinal load carrying member). 
     After the electronic components (sometimes designated generally in the drawings by the letter “E”) are assembled to the medial  23  side of mounting member  22 , female mould  15  is used to complete the method of construction of the present invention as shown in FIG. 9-13. In FIG. 9, the female mould  15  is placed over the electronic components “E” beginning with the distal end portion of receiver tube  37  and the distal end portion of vent tube  30  as indicated by arrows  40  in FIG. 9. A plurality of three openings  41 ,  42 ,  43  are provided at distal end  44  of female mould  15  as shown in FIG.  9 . The proximal end  45  of female mould  15  provides an annular edge surface  19  that engages the medial  23  side of mounting member  22  as indicated by the dotted line  46  in FIG.  9 . 
     A joint is formed between annular edge surface  19  of female mould  15  and medial surface  23  of mounting member  22  at a position schematically indicated as dotted line  46  in FIG. 9, using the method of the present invention. The medial surface  23  of mounting member  22  is cleaned with a suitable solvent. Acetone can be used as a solvent in the case of a mounting plate  22  that is made of acrylic. The medial surface  23  of mounting member  22  is then painted with a primer using a swab or brush. The primer is allowed to dry. A bonding agent is then applied to the medial surface  23  of mounting member  22  and allowed to dry. The bonding agent or bonding enhancer can be product A-320 of Factor II, Inc. of Lakeside, Ariz., which is a member of the chemical family “silicone primer”. 
     The female mould  15  is placed against the medial side  23  of mounting member  22 . A liquid acrylic is used to form an acrylic seam at the interface of annular edge surface  19  of female mould and the medial side  23  of mounting member  22  (see FIG.  10 ). As the female mould  15  is assembled to mounting member  22 , vent tube  30  passes through opening  41 . Receiver tube  37  passes through opening  42 . The opening  43  is then used for injection of filler material  50  (e.g. via needle  49 ) as shown by arrows  51 ,  52  in FIG.  11 . During this process, temporary seal  47  holds the liquid filler material  50  within the interior  53  that is formed by female mould  15  and mounting member  22 . The filler material  50  can be a liquid during the injection step of FIG. 11 so that it encapsulates at least the receiver/speaker electronic component  35  and preferably other components as well. 
     In FIG. 12, the female mould  15  is removed after the material  50  has set. The mounting member  22  (which can be in the form of a circular, generally flat face plate) is then cut at the phantom line  46  that basically tracks the periphery of female mould  15  at annular edge surface  19  at proximal end  45  thereof. This cutting of the unused, unneeded part of mounting member  22  is shown in FIG.  13 . FIGS. 14-17 show the completed apparatus  10  of the present invention. 
     The present invention provides a soft, yet solid hearing aid instrument that will provide a more appropriate environment for both the high fidelity performance of today&#39;s advanced circuitry and the dynamic ear canal. 
     The present invention teaches a soft construction of at least the distal portion of the apparatus  10  so that at least the receiver/speaker is encapsulated with the soft material  50 . This construction results in a precise representation of the human ear canal, flex with jaw motion, and cushion for the embedded electronic components “E”. 
     FIG. 18 demonstrates real ear occlusion gain (REOG) finding obtained from a wearer having a tortuous ear canal. The curve  101  represents the REOG of a hard shell, hollow type hearing aid instrument. The curve  102  represents the REOG of an instrument  10  made according to the method of the present invention. As can be seen in FIG. 18, the present invention instrument provided  20  dB more attenuation than did the hard shell, hallow hearing aid instrument represented by the curve  101 . Because of the sharp first directional bend of the wearer&#39;s ear canal, the hard shell instrument could not be inserted without modification. The apparatus  10  of the present invention was insertable without modification thereby yielding a tighter seal in the wearer&#39;s ear. 
     FIG. 19 is a graphical representation that demonstrates real ear aided gain (REAG) findings obtained from a wearer having a tortuous ear canal. The curves shown ( 103 ,  104 ) were obtained from the instruments used to generate the finding shown in FIG.  18 . Curve  103  represent REAG before feedback of the apparatus  10  of the present invention. Curve  104  demonstrates the REAG before feedback of a hard shell, hollow type hearing aid instrument of the prior art. As can be seen in FIG. 19, the instrument  10  of the present invention represented by curve  103  provided more gain across the frequencies. This REAG is inversely proportional to the amount of occlusion gain (REOG) or attenuation provided by the apparatus  10  of the present invention. It should be restated that, because of the sharp first directional bend of the wearer&#39;s ear canal, the hard shell, hollow type instrument of the prior art could not be inserted without being modified. The apparatus of the present invention was insertable without modification, thus the present invention provides higher added gain values (REAG) when a more negative REOG can be achieved while maintaining comfort. 
     The apparatus  10  of the present invention will result in a better utilization of advanced circuitry and a more comfortable hearing instrument. The soft construction solves the problem of peripheral leakage, poor fit, and pivotal displacement that often occurs with jaw motion. Another problem that is solved with the present invention is the elimination of internal cross-talk of components housed in hollow shell type hearing aids. 
     The following table lists the parts numbers and parts descriptions as used herein and in the drawings attached hereto. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 PARTS LIST 
               
             
          
           
               
                 Part Number 
                 Description 
               
               
                   
               
               
                  1 
                 ear 
               
               
                  2 
                 external auditory 
               
               
                   
                 canal 
               
               
                  3 
                 ear canal wall 
               
               
                  4 
                 auricle 
               
               
                  5 
                 isthmus 
               
               
                  6 
                 tympanic membrane 
               
               
                  7 
                 middle ear 
               
               
                  8 
                 inner ear 
               
               
                  9 
                 dam 
               
               
                 10 
                 hearing aid 
               
               
                 11 
                 form 
               
               
                 12 
                 knife 
               
               
                 13 
                 excess material 
               
               
                 14 
                 excess material 
               
               
                 15 
                 female mold 
               
               
                 16 
                 sagittal plane 
               
               
                 17 
                 vessel 
               
               
                 18 
                 technician&#39;s fingers 
               
               
                 19 
                 annular surface 
               
               
                 20 
                 arrow 
               
               
                 21 
                 mold material 
               
               
                 22 
                 mounting member 
               
               
                 23 
                 medial side 
               
               
                 24 
                 lateral side 
               
               
                 25 
                 microphone 
               
               
                 26 
                 battery compartment 
               
               
                 27 
                 volume control 
               
               
                 28 
                 programming socket 
               
               
                 29 
                 vent opening 
               
               
                 30 
                 vent tube 
               
               
                 31 
                 battery 
               
               
                 32 
                 battery terminal 
               
               
                 33 
                 voltage regulating 
               
               
                   
                 capacitor 
               
               
                 34 
                 amplifier/ 
               
               
                   
                 microprocessor 
               
               
                 35 
                 receiver 
               
               
                 36 
                 receiver port 
               
               
                 37 
                 receiver tube 
               
               
                 38 
                 wiring harness 
               
               
                 39 
                 s-loop wires 
               
               
                 40 
                 arrow 
               
               
                 41 
                 opening 
               
               
                 42 
                 opening 
               
               
                 43 
                 opening 
               
               
                 44 
                 distal end 
               
               
                 45 
                 proximal end 
               
               
                 46 
                 dotted line 
               
               
                 47 
                 temporary seal 
               
               
                 48 
                 syringe 
               
               
                 49 
                 needle 
               
               
                 50 
                 filler material 
               
               
                 51 
                 arrow 
               
               
                 52 
                 arrow 
               
               
                 53 
                 interior space 
               
               
                 54 
                 silicone plug 
               
               
                 55 
                 monofilament cantilever 
               
               
                 56 
                 opening 
               
               
                 57 
                 fastener 
               
               
                 58 
                 small opening 
               
               
                 59 
                 large opening 
               
               
                   
               
             
          
         
       
     
     the foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.

Technology Category: 5