Absorbent article comprising a wetness detector

The absorbent article of any one of the preceding claims, wherein there is provided a plurality of liquid discharge sensors each capable of determining the presence of a liquid discharge in a respective zone of the absorbent core, wherein there is further provided a plurality of holes in the back sheet, each liquid discharge sensor communicating with the absorbent core through at least one hole in the back sheet.

The absorbent article of any one of the preceding claims, wherein there is provided a plurality of holes in the back sheet, each hole revealing to the absorbent core an underlying conductive portion of a liquid discharge sensor.

The absorbent article of any one of the preceding claims, wherein there is a plurality of holes in the back sheet and a plurality of electrically conductive paths that are electrically isolated from one another to form the at least one liquid discharge sensor, wherein each of the holes communicate a respective conductive path with the absorbent core so that current is able to flow from the conductive path in one hole to another conductive path in another hole when the absorbent core is wet.

The absorbent article of any one of the preceding claims, wherein the back sheet, apart from at the at least one hole, otherwise electrically insulates conductive paths forming the at least one liquid discharge sensor from the absorbent core.

The absorbent article of any one of the preceding claims, wherein the total area of the at least one hole is less than 50%, 40%, 30%, 20% or 10% of the total area of the absorbent core when the absorbent article is laid out flat and a plan view of the absorbent core is taken.

The absorbent article of any one of the preceding claims, wherein the total area exposed to the absorbent core of conductive paths or lines making up the at least one liquid discharge sensor is less than 50%, 40%, 30%, 20% or 10% of the total area of the conductive paths or lines when the absorbent article is laid out flat and the absorbent core is viewed in plan.

The absorbent article of any one of the preceding claims, wherein conductive paths forming the at least one liquid discharge sensor are in the form of lines.

The absorbent article of any one of the preceding claims, wherein the at least one liquid discharge sensor is provided by conductive material that is partly communicated with the absorbent core by the at least one hole.

The absorbent article of any one of the preceding claims, wherein the at least one liquid discharge sensor is disposed on a carrier sheet or substrate.

The absorbent article of any one of the preceding claims, wherein the back sheet is made of a liquid impermeable material, and wherein the back sheet is at least part of a back liner of a diaper.

The absorbent article of any one of the preceding claims, wherein the absorbent article also includes a liquid permeable body side liner, wherein the absorbent core is sandwiched between the back sheet and the body side liner.

The absorbent article of any one of the preceding claims, wherein the at least one liquid discharge sensor is made up of a plurality of conductive members printed, coated or adhered to a body side surface of a substrate.

The absorbent article of any one of the preceding claims, including a plurality of conductive leads extending from the at least one liquid discharge sensor to a common contact area, wherein the leads are covered by the back sheet.

The absorbent article of any one of the preceding claims, wherein a plurality of conductive lines are disposed on a first electrically insulating layer that are partially covered by the back sheet, wherein portions of the conductive lines exposed by the at least one hole in the back sheet are in electrical communication with the absorbent core, thereby providing electrodes of the at least one liquid discharge sensor, and wherein portions of the conductive lines covered by the back sheet include leads extending between each electrode and a control unit attachment area, the back sheet ensuring the leads are electrically insulated from the absorbent core, wherein the electrodes are arranged so that a plurality of longitudinally spaced liquid detection zones are provided, each detection zone defined between a pair of electrodes that are electrically isolated from one another when the absorbent core is dry and which are arranged so that when the control unit connects an electric potential to corresponding leads and when the absorbent core is wet, a conductive bridge is formed between the pair of electrodes by the wet absorbent core, wherein a longitudinal axis extends in a front to rear direction of the absorbent article when worn.

The absorbent article of any one of the preceding claims, wherein the back sheet provides a frame of insulating material around a conductive portion of the liquid discharge sensor exposed by the at least one hole.

The absorbent article of any one the preceding claims, wherein the at least one hole in the back sheet includes a plurality of holes in the back sheet that form windows exposing portions of conductive lines or members to the absorbent core to form a plurality of liquid discharge sensors, wherein the windows are longitudinally spaced so as to form respective liquid discharge sensors between longitudinally spaced pairs of exposed portions of the conductive lines or members.

The absorbent article of any one of the preceding claims, wherein conductive lines or members making up the at least one liquid discharge sensor extend to the at least one hole on one side of the at least one hole, bridge the at least one hole and continue to extend from the at least one hole on an opposed side of the at least one hole.

The absorbent article of any one of the preceding claims, wherein the at least one liquid discharge sensor comprises a plurality of longitudinally spaced conductive members that are in communication with the absorbent core through the at least one hole, wherein the front most conductive member communicating with the absorbent core and the rear most conductive member communicating with the absorbent core along the front to rear longitudinal axis of the absorbent core are located a distance apart of at least 0.1L, 0.2L, 0.3L, 0.4L or 0.5L, wherein L is a total longitudinal length of the absorbent core when the absorbent article is laid out flat and viewed in plan.

The absorbent article of any one of the preceding claims, wherein the at least one liquid discharge sensor comprises at least one, preferably a plurality, pair of longitudinally adjacent conductive members communicating with the absorbent core through the at least one hole, wherein the pair of adjacent conductive members (or when a plurality of pairs of conductive members are provided, the pair closest to a central lateral axis of the absorbent core) are located a distance apart of less than or equal to 0.8L, 0.7L, 0.6L or 0.5L, wherein L is a total longitudinal length of the absorbent core when the absorbent article is laid out flat and viewed in plan.

The absorbent article of any one of the preceding claims, wherein the at least one liquid discharge sensor comprises a plurality of liquid discharge sensors that are longitudinally distributed over at least 0.5L, 0.6L, 0.7L, 0.8L or 0.9L, wherein L is a total length of the absorbent core when viewed in plan when the absorbent article is laid out flat.

A method of making an absorbent article comprising providing an electrically conductive pattern on a substrate, providing electrically insulating back sheet material for the absorbent article including at least one hole, providing an absorbent core, and making the absorbent article so that the substrate is disposed on a back side of the back sheet, the absorbent core is disposed on a body side of the back sheet, the absorbent core is disposed on the at least one hole, and so that part of the conductive pattern is revealed to the absorbent core through the at least one hole, whereby current flow is altered between sub-parts of the part of the conductive pattern when a portion of the absorbent core connecting the sub-parts changes from a dry state to a wet state.

A laminate comprising a first electrically insulating layer, and a second electrically insulating layer that are laminated together with a plurality of conductive lines or members sandwiched between the first and second electrically insulating layers, wherein each of the conductive lines or members are electrically separate from one another, wherein the second electrically insulating layer includes at least one hole to expose a portion of each of the conductive lines or members, wherein the laminate is such that an absorbent core is able to be placed on the second insulating layer to cover the exposed portions with the absorbent core so that current can pass from the exposed portions to the absorbent core when the absorbent core is wet at the respective location of the exposed portions.

An absorbent article, comprising a plurality of conductive lines extending on an upper side of an electrically insulating layer and in electrical contact with an absorbent core of the absorbent article, wherein the plurality of conductive lines extend through the electrically insulating layer to extend on a lower side of the electrically insulating layer in a first direction, wherein the conductive lines extend laterally on the upper and lower sides of the insulating layer, and wherein respective leads extend longitudinally between each conductive line on the lower side of the electrically insulating layer and a control unit attachment area.

A method of manufacturing an absorbent article, comprising providing an electrically insulating back sheet having a plurality of conductive units, the conductive units respectively comprising a conductive portion disposed on a body side of the electrically insulating back sheet, a conductive line or member disposed and extending on a back side of the back sheet and a conductive path connecting the conductive line and the conductive portion by passing through the back sheet;

• providing a substrate having a plurality of conductive leads disposed thereon;
• disposing the substrate on the back side of the back sheet so that the leads respectively connect to the conductive lines or members on the back side of the back sheet;
• wherein the absorbent article is made having an absorbent core disposed on the body side of the back sheet so that the conductive portions on the body side of the back sheet are useable to determine a change in electrical property when the absorbent core changes from a dry state to a wet state.