Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1998-05-29
2001-06-12
Hofsass, Jeffery (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
60, 60, 60, C604S361000
Reexamination Certificate
active
06246330
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to systems and devices for monitoring the condition of a diaper, other undergarment, bedding or the like; particularly with regard to the clean or soiled status thereof, and specifically to a sensor and monitor/alarm assembly useful as an elimination-absorber monitoring system.
BACKGROUND INFORMATION
Inventors have long sought to provide a system of associated devices for effectively monitoring the condition of a diaper, other undergarment, bedding or the like. While the present invention provides an elimination-absorber monitoring system useful in each of these environments, a preferred embodiment is utilized in conjunction with a disposable diaper. Thus, for purposes of brevity in the present specification, the term “diaper” shall indicate any of the above-described use environments, except where otherwise specifically stated or apparent from context.
The art is replete with examples of prior attempts to satisfy the need for an elimination-absorber monitoring system. Each has, for one reason or another, apparently failed to achieve significant implementation and consumer acceptance. Upon review, the prior systems appear either impractical, unsuitable to the use environment, unworkable and/or uneconomical—largely for one or more of the following reasons: failure to provide an appropriate sensor response or alarm criteria with respect to urine-soiling; inability to detect fecal matter, or to provide an appropriate sensor response or alarm criteria with respect to feces-soiling; lack of important user-oriented features; and unsuitability to cost-effective manufacturing.
PRIOR ART
Most previous systems have utilized the measurement of electrical conductivity between two spaced electrodes disposed somewhere on top of, within, or under the absorbent layers of a diaper, to detect the presence of liquid urine when it bridged some path between the electrodes. This approach is described in U.S. Pat. No. 3,460,123 (Bass), U.S. Pat. No. 4,356,818 (Macias), U.S. Pat. No. 4,800,370 (Vetecnik), U.S. Pat. No. 4,539,559 (Kelly), U.S. Pat. No. 4,768,023 (Xie), U.S. Pat. No. 5,036,859 (Brown), U.S. Pat. Nos. 5,264,830 and 5,392,032 (Kline), U.S. Pat. No. 4,205,672 (Dvorak), and U.S. Pat. Nos. 5,266,928 and 5,395,358 (Lu). These systems all depended on the relatively high conductivity of urine, as compared to the typically low conductivity of unsoiled, dry diaper materials. Several of these prior inventors clearly assumed that the key to a useful “diaper wetness” alarm (as their objective was often termed) would be the detection of virtually any urine in a diaper. They also recognized that, depending on the sensor configuration, urine could miss the intended target. Thus, variations of this approach incorporated either distributed (e.g., screen-like) electrodes or various absorbent pads or modifications of a diaper to help collect, funnel or direct urine flow to bridge the sensing electrodes, e.g., U.S. Pat. No. 4,356,818 (Macias). However, this focus on the detection of simple “wetness” resultant from urination—as opposed to the far more useful determination that an elimination-absorber actually required changing—failed to answer the real needs of caregivers and diaper-wearers. As with all the prior systems, seemingly little emphasis was placed on defining and obtaining truly user-responsive sensor performance. While this simple “wetness detection” focus may have appeared somewhat workable, as applied to certain cloth or early low-absorbency diapers, it did not adequately address the effects of widely differing flow-rates and volumes in various urination events and situations. Moreover, for reasons that shall be explained below, this approach was completely incompatible with the properties (and particularly the much greater capacity) of modern disposable diapers. Thus, previous systems based on simple “wetness detection” typically either failed to work consistently, or were prone to meaningless or premature alarm indications.
Some prior attempts took the view that a “soiled” diaper condition could be deduced by simply detecting the arrival of urine at the bottom (just inside the outer cover) of a diaper, i.e., that this would indicate when the diaper had reached its absorbent capacity. However, high-absorbency diapers are specifically designed to prevent urine from soaking to the outer cover, at least during the expected wearing time. Because urine permeates into and through a diaper with at least some time delay, additional urine will continue to collect after it first reaches a pair of sensing electrodes. If urine is detected only after soaking to the bottom of a diaper, the continued accumulation will tend to quickly spread along the inside of the cover, and quite likely leak out before the diaper can be changed. Thus, the determination of a fully saturated condition based on the sudden presence of urine at the bottom layers is not practically useful. Even completely non-electronic approaches to diaper monitoring, such as the “happy face” visual indicators incorporated into the outer cover of Fitti™ brand diapers, can similarly suffer from the limitations of over-simplified alarm criteria and inappropriate, inconsistent, or untimely sensor response. Also, such purely visual wetness-indicating devices, which are necessarily disposed directly on a diaper cover, have limited value for other reasons. Just as with traditional methods, they still require frequent and continual checking by a caregiver—and the awkward removal of clothing layers worn over a diaper—to permit viewing of the indicator. They thereby fail to provide a convenient, automatic, attention-getting signal that a diaper needs changing.
Still other inventors tried to “intercept” the flow of urine somewhere in the mid-layers of a diaper, but as will be appreciated by those skilled in the art, another problem results from the modern disposable diaper being such an aggressive absorber. No choice of conductivity-sensing path within such diapers (including midway through the absorbent layers) is likely to conveniently go from “dry” to fully “wet” at such time as to appropriately reflect a “needs to be changed” condition. In some such diapers, “super-absorbent” particles or polymer jells have been used to dramatically increase the liquid-holding capacity in a central core of the absorbent structure. These central absorbers are typically surrounded by conventional (e.g., cellulose based) absorbent wadding because the super-absorbers tend to react relatively slowly in absorbing liquid, as compared to the conventional materials. This means that the distribution of liquid through the diaper is highly non-uniform and it changes markedly after a urination event, as the super-absorber core gradually pulls liquid out of the conventional absorbent bulk. Also, with intermediate levels of moisture in any type of diaper (where the absorbent material is not yet completely saturated), urine can accumulate gradually or unevenly—often separated into discontinuous droplets or unpredictably scattered wet or merely damp regions. Thus, these regions may not happen to span a chosen path between electrodes so that the urine can be reliably detected. Moreover, the mere presence of relatively high conductivity (and hence the presence of liquid) along any given path through a diaper may not reflect a true “needs to be changed” condition (i.e., correlate with caregiver expectations or with traditional diaper inspection methods), particularly in the case of modern high-absorbency, disposable diapers. As explained above, none of the foregoing simple conductivity-based systems reflected a truly appropriate sensor response or “alarm criteria” with respect to urine-soiling of diapers. They typically responded either immediately or prematurely to the presence of trivial amounts of urine passing into a diaper; or alternatively, they responded either inconsistently, or not until after the diaper was soaked beyond its safe absorbent capacity—depending primarily on the choice of sensing location.
Other prior devices h
Hofsass Jeffery
La Anh
Lowin David A.
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