Abstract:
A baby bottle assembly including a nipple having a substantially flat membrane defining multiple pinholes for controlling the flow of liquid. The nipple is mounted on a cap that screws onto the bottle body. The nipple is formed from a suitable elastomeric material (e.g., soft rubber, thermoplastic elastomer, or silicone) such that the membrane stretches when subjected to a differential pressure. The pinholes are formed by puncturing the membrane while subjecting the membrane to radial tension, and using one or more pins having a substantially circular cross-section and sized such that each pinhole is closed by the surrounding elastomeric material when the pins are removed.

Description:
FIELD OF THE INVENTION 
   The present invention relates to baby bottle assemblies, and more specifically it relates to nipples for baby bottle assemblies that exhibits adjustable flow characteristics. 
   RELATED ART 
   Natural breasts generally adjust to a baby&#39;s sucking power so that its nutritional needs are met as it grows. When newborn, an infant&#39;s sucking force is relatively weak and its appetite is relatively small, so the female breast supplies a relatively low flow rate. As the infant grows into a toddler, its sucking force increases along with its appetite. Female breasts are able to adjust to this increased demand by providing a higher flow rate in response to the increased sucking force and appetite. 
   Unlike breast-fed babies, bottle-fed babies often experience feeding related problems associated with conventional nipple products that exhibit substantially fixed milk flow rates. That is, many conventional nipples are provided with an opening that is sized to facilitate a relatively fixed amount of milk flow depending on the size of the baby. Nipples for newborn babies have relative small holes that support relatively low flow rates, while nipples for toddlers typically include relatively large holes or slits to facilitate greater flow rates. A problem arises when a baby&#39;s draw rate fails to match the particular nipple from which that baby is being fed. For example, when a newborn infant is fed from a toddler nipple, the high flow rate can result in choking and coughing. Conversely, when a toddler is presented with a newborn baby&#39;s nipple, the low flow rate can cause frustration. In many instances, parents experience a great deal of anxiety trying to match the correct nipple to a baby&#39;s ever-changing milk flow demand. 
   What is needed is a nipple for a baby bottle that automatically adjusts its flow rate to the needs of a growing baby, thereby allowing a single nipple to be used for both newborn infants and toddlers. 
   SUMMARY 
   The present invention is directed to a baby bottle assembly including a nipple having a substantially flat membrane defining multiple pinholes for controlling the flow of liquid. The nipple is formed from a suitable elastomeric material (e.g., soft rubber, thermoplastic elastomer, or silicone) such that the membrane stretches when subjected to a differential pressure. The pinholes are formed by puncturing the membrane while applying radial tension such that the membrane stretches at least 1% of its resting diameter. The puncturing process is performed using one or more pins having a substantially circular cross-section and sized such that each pinhole is closed by the surrounding elastomeric material when the radial tension is removed. According to an aspect of the present invention, during use the pinholes are opened by an amount determined by the amount of sucking force applied by the baby. For example, when a relatively small infant applies a relatively weak sucking force to the nipple, the membrane stretches a relatively small amount, and the pinholes open to a relatively small size, thereby resulting in a relatively low flow of liquid through the nipple. In contrast, when a relatively large toddler applies a relatively strong sucking force to the nipple, the membrane stretches a relatively large amount, and the pinholes open to a relatively large size, thereby resulting in a relatively large flow of liquid through the nipple. Accordingly, the present invention avoids the problems associated with conventional nipples by automatically adjusting the amount of flow according to the milk flow demand of the infant/toddler. 
   According to an embodiment of the present invention, the nipple includes a disk shaped flange, a lower conical wall section extending upward from the flange, a neck region located at an upper end of the lower conical wall section, and an upper conical wall section extending upward from the neck region. The disk-shaped membrane is formed on an upper portion of the upper conical wall section. The lower conical wall section defines a first diameter, the neck region defines a second diameter, and the membrane defines a third diameter, where the second diameter of the neck region is smaller than the first diameter of the lower conical wall section and the third diameter of the membrane. The flange and conical walls of the nipple are formed from relatively thick portions of elastomeric material (e.g., silicone, thermoplastic elastomer, or soft rubber), and the membrane is formed from a relatively thin section of the elastomeric material. 
   According to another embodiment of the present invention, the nipple includes a lower flange, a lower wall section extending upward from the flange, an oval neck structure extending from an upper end of the lower wall section, and an oval membrane formed at an upper edge of the upper wall section. As in the first embodiment, the flange and walls of the nipple are formed from relatively thick portions of elastomeric material (e.g., silicone, thermoplastic elastomer, or soft rubber), and the membrane is formed from a relatively thin section of the elastomeric material. 
   The present invention will be more fully understood in view of the following description and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a partial cut-away side view showing a baby bottle assembly according to an embodiment of the present invention; 
       FIG. 2  is a cross-sectional side view showing a nipple according to an embodiment of the present invention; 
       FIG. 3  is a top plan view of the nipple shown in  FIG. 2 ; and 
       FIGS. 4(A) ,  4 (B) and  4 (C) are simplified enlarged cross-sectional views showing the formation and opening of a pinhole formed in the nipple of  FIG. 2  during operation; 
       FIG. 5  is a top plan view showing a nipple according to another embodiment of the present invention; and 
       FIGS. 6(A) and 6(B)  are cross-sectional side views of the nipple shown in  FIG. 5  as taken along section lines  6 A— 6 A and  6 B— 6 B. 
   

   DETAILED DESCRIPTION 
     FIG. 1  is a partial cut-away side view showing a baby bottle assembly  100  according to an embodiment of the present invention. Baby bottle assembly  100  generally includes a substantially cylindrical bottle body  110 , a ring-shaped cap  140 , and an elastomeric flow control nipple  150  extending through an opening formed in cap  140 . 
   Bottle body  110  is a standard baby bottle including a roughly cylindrical sidewall  111  having a threaded upper neck  113 , and a bottom wall  115  located at a lower edge of sidewall  111 . Sidewall  111  and bottom wall  115  define a beverage storage chamber  117  for storing a fluid beverage (i.e., infant formula or milk). Bottle body  110  is molded from a suitable plastic using known methods. 
   Cap  140  is also a substantially standard piece including a cylindrical base portion  142  having threaded inside surface, and a disk-shaped upper portion  145  defining a central opening through which a portion of nipple  150  extends. When cap  140  is connected (screwed) onto bottle body  110 , the threads formed on cylindrical base portion  142  mate with threaded neck  113 . Cap  140  is also molded from a suitable plastic using known methods. 
   Referring to  FIGS. 2 and 3 , nipple  150  is formed from a suitable elastomeric material (e.g., soft rubber, thermoplastic elastomer, or silicone) , and includes a lower disk-shaped flange  151 , a lower conical wall section  152  extending upward from flange  151 , a neck region  153  formed above lower conical wall section  152 , an upper conical wall section  154  extending upward from neck region  153 , and a substantially flat, disk-shaped upper membrane  155  located at the upper portion of upper conical wall section  154 . Lower conical wall section  152 , neck region  153 , upper conical region  154 , and membrane  155  define an interior chamber  157 . As indicted in  FIG. 1 , when mounted in bottle assembly  100 , a ring-shaped portion of flange  151  is pinched between an upper edge of neck  113  and a portion of upper portion  145  of cap  140 , and interior chamber  157  of nipple  150  communicates with storage chamber  117  of bottle body  110 . Lower conical wall section  152  extends through the opening defined in disk-shaped upper portion  145  of cap  140 , and gradually tapers from a relatively wide diameter near flange  151  to a relatively narrow diameter D 2  at neck region  153 . Above neck region  153 , upper conical wall section  154  again widens to a third, relatively wide diameter D 3 , which corresponds with the diameter of disk-shaped upper membrane  155 . Flange  151  and conical sections  152  and  154  are formed using relatively thick sections of the elastomeric material, in comparison to membrane  155 , which is relatively thin. In one embodiment, nipple  150  is molded as a single integral piece using silicone. In this embodiment, flange  151  has a thickness T 1  in the range of 0.06 to 0.1 inches (e.g., approximately 0.1 inches) and a diameter D 1  of approximately 2 inches, lower conical wall section  154  has a thickness T 2  in the range of 0.04 to 0.08 inches (e.g., approximately 0.06 inches), and membrane  155  has a diameter D 3  of approximately 0.75 inches and thickness T 3  in the range of 0.01 to 0.1 inches (e.g., approximately 0.02 inches). 
   In accordance with the present invention, several pinholes  158  are formed in membrane  155  to facilitate adjustable liquid flow from storage chamber  117  through nipple  150 . As indicated in  FIG. 4(A) , each pinhole  158  is formed by piercing membrane  155  with a pin  410 , or other sharp pointed object, such that the pinhole is closed by the surrounding elastomeric material when pin  410  is subsequently removed. In a preferred embodiment, each pin  410  is formed with a continuously curved (e.g., circular) cross section such that each pinhole  158  is substantially circular (i.e., does not have a slit or fold that would be formed by a cutting element having an edge). Note that a pin having a diameter DIA of approximately 0.025 inches was used to produce successful pinholes in a membrane having a thickness of approximately 0.02 inches. In an alternative embodiment, a mold used to produce nipple  150  may include several pin-like structures that produce pinhole voids in molded elastomeric material, although this approach may result in continuously open holes. The number of pinholes  158  determines the amount of liquid flow through membrane  155  during use, as discussed below. 
   Referring again to  FIG. 1 , during operation nipple  150  is mounted onto cap  140  such that flange  151  is located against a lower surface of upper portion  145 , and the remainder of nipple  150  extends through and is positioned above upper portion  145  of cap  140 . A liquid (e.g., a beverage such as formula or milk) is then poured into storage chamber  117  of bottle body  110 , and cap  140  is secured onto threaded upper neck  113 . In this arrangement, while atmospheric equilibrium is maintained (i.e., the pressure inside bottle body  110  is equal to the pressure outside nipple  150 ), membrane  155  remains in the unstretched state illustrated in  FIG. 4(A) , wherein pinholes  158  remain closed to prevent leakage. As shown in  FIG. 2 , in one embodiment, the unstressed membrane  155  essentially entirely lies in (defines) a plane P. 
   According to an aspect of the present invention, the amount of liquid flow through membrane  155  is controlled by the amount of vacuum generating by an infant/child sucking on nipple  150 , thereby allowing nipple  150  to automatically adjust liquid flow to the size and/or strength of each infant/child. As indicated in  FIG. 2 , during use (e.g., when an infant/child sucks on nipple  150  with bottle body  110  tipped such that liquid flows into nipple chamber  157 ), a pressure differential is generated such that a relatively high pressure inside storage chamber  117  becomes greater than a relatively low pressure in the infant/child&#39;s mouth, thereby causing membrane  155 ′ to stretch outward from plane P. As indicated in  FIG. 4(B) , the partially stretched membrane  155 ′ causes pinholes  158 ′ to open, thereby allowing the liquid beverage to flow through at a rate that is proportional to the amount pinhole  158 ′ is open. That is, the amount of membrane stretching determines the size of the opened pinholes  158 ′, which in turn determines the amount of liquid flowing through membrane  155 ′. For example, as indicated in  FIG. 4(C) , in the case where a larger infant/child creates a greater vacuum (i.e., a higher pressure differential), then membrane  155 ″ becomes even more stretched, thereby causing pinholes  158 ″ to open even further and allowing a greater amount of liquid flow through membrane  155 ″. Subsequently, when the pressure differential is relieved (i.e., the child stops sucking) and atmospheric equilibrium is re-established by back venting through pinholes  158 . Membrane  155  then substantially returns to its unstretched state, and pinholes  158  return to the closed state shown in  FIG. 4(A) . Note that because pinholes  158  do not include slits that can become weakened and/or trap deposits that can prevent slit flap closure, nipples formed in accordance with the present invention facilitates leak-free operation that is substantially more reliable than that of fixed hole or slit-based conventional nipple products. 
   As mentioned above, the number of pinholes  158  determines the amount of liquid flow through membrane  155  during use. Because each pinhole  158  only opens a small amount, the amount of liquid passing through each pinhole  158  during use is quite small. Accordingly, multiple pinholes  158  are arranged in a pattern that collectively facilitates desired flow conditions. In an experiment using a silicone membrane having thickness of 0.02 inches and a diameter of approximately ¾ inches, a pattern of less than ten spaced-apart pinholes was found to produce insufficient liquid flow during normal use, whereas a pattern of forty-seven pinholes was found to produce an optimal liquid flow. Of course, the number and pattern of pinholes  158  depends on a number of factors, and the pattern shown in  FIG. 3  is not intended to be limiting, as further evidenced by the second embodiment disclosed below. Further, although a flat membrane  155  facilitates easier formation of pinholes  158 , it may also be possible to form membrane  155  with a slightly bent or curved surface. 
     FIGS. 5 ,  6 (A) and  6 (B) show a nipple  550  according to another embodiment of the present invention. Nipple  550  includes a lower flange  551 , a lower wall section  552  extending upward from flange  551 , an oval neck structure  554  extending upward from lower wall section  552 , and an flat oval membrane  555  formed at an upper edge of neck structure  554 . The dimensions and thicknesses associated with nipple  550  are similar to those described above with reference to the first embodiment. Also, similar to the first embodiment, membrane  555  is essentially flat such that it defines a plane P 1 . Note that, due to the smaller size of membrane  555  (i.e., approximately one-half inch along the short axis and three-quarters of an inch along the long axis), the number of holes  558  formed therein is smaller (e.g., thirty-seven). To compensate for the smaller number of pinholes  558 , the membrane thickness may be reduced (e.g., to 0.015 inches) to facilitate the same fluid flow, as compared to that of thicker membranes having a larger number of pinholes. Note also that stiffening ribs  559  may be integrally molded on the inside of neck structure  554  to resist collapse of nipple  550  during use. In one embodiment, membrane  555  is indented by an amount I (e.g., 0.015 inches) below the uppermost portion of neck structure  554 . 
   In addition to the specific embodiment disclosed herein, other features and aspects may be added to the novel baby bottle nipple that fall within the spirit and scope of the present invention. Therefore, the invention is limited only by the following claims.