“ absorbent articles ” as referred to herein are primarily sanitary napkins , pantiliners , or incontinence pads that are worn in the crotch region of an undergarment . it is even conceivable that baby diapers , adult incontinence diapers , and human waste management devices benefit from the present invention even though they are conventionally not worn in conjunction with an undergarment . the term ‘ color ’ as referred to herein include any primary color , i . e ., white , black , red , blue , violet , orange , yellow , green , and indigo as well as any declination thereof or mixture thereof . the term ‘ non - color ’ or ‘ non - colored ’ refers to the color white which is further defined as those colors having an l * value of at least 90 , an a * value equal to 0 ≠ 2 , and a b * value equal to 0 ≠ 2 . the term ‘ disposable ’ is used herein to describe absorbent articles that are not intended to be launched or otherwise restored or reused as absorbent articles ( i . e ., they are intended to be discarded after a single use and , preferably to be recycled , composted or otherwise disposed of in an environmentally compatible manner ). non - limiting examples of panty liners and sanitary napkins which may be provided with a multi - tone signal that operates to create depth perception include those manufactured by the procter & amp ; gamble company of cincinnati , ohio as : always ® pantiliners with driweave ® manufactured according to u . s . pat . nos . 4 , 324 , 246 ; 4 , 463 , 045 ; and 6 , 004 , 893 ; always ® ultrathin slender maxi with wings manufactured according to u . s . pat . nos . 4 , 342 , 314 , 4 , 463 , 045 , 4 , 556 , 146 , b1 4 , 589 , 876 , 4 , 687 , 478 , 4 , 950 , 264 , 5 , 009 , 653 , 5 , 267 , 992 , and re . 32 , 649 ; always ® regular maxi ; always ® ultra maxi with wings ; always ® maxi with wings ; always ® ultra long maxi with wings ; always ® long super maxi with wings ; and always ® overnight maxi with wings , each aforesaid publication being incorporated by reference herein . [ 0023 ] fig1 provides a perspective view of the absorbent article 10 . fig2 provides a planar view of the absorbent article of fig1 . the absorbent article 10 herein has an upper surface 13 , a lower surface 14 ( not seen ) and a periphery 12 comprising a topsheet 25 having a bottom surface 27 ( not shown ) and a viewing surface 28 positioned opposite to the bottom surface 27 . the viewing surface 28 faces upwardly towards the upper surface 13 of the absorbent article 10 . the absorbent article 10 further comprises a backsheet 15 ( not shown ) having a garment facing surface 16 ( not shown ) and a user facing surface 17 ( not shown ) positioned oppositely to the garment facing surface 16 , the backsheet 15 being joined to the topsheet 25 . the absorbent article 10 also comprises an absorbent core 20 having a top surface 21 and a bottom surface 22 ( not shown ) that is positioned opposite to the top surface 21 . the absorbent core 20 is positioned between the topsheet 25 and the backsheet 15 . in the embodiment shown in fig1 the absorbent article 10 has at least two portions , i . e ., a colored portion 40 and a non - colored portion 50 . the colored portion 40 and the non - colored portion 50 are viewable from the viewing surface 28 of the topsheet 25 . the colored portion 40 has at least two shades , a first shade 42 and a second shade 44 . preferably , but not necessarily , and as is shown in fig1 the first shade 42 is positioned substantially within the second shade 44 . the second shade 44 is different , either in lightness , darkness , and / or color , from the first shade 42 . the multi - shades operate to create a perception of depth within the absorbent article by a user looking upon the viewing surface 28 of the topsheet 25 . in one embodiment herein , the first shade 42 of the color is darker than the second shade 44 of the color . alternatively , the first shade 42 is lighter than the second shade 44 . the lightness and darkness of the shades , whether two or greater than two shades , are configured to create a perception of depth by a user looking upon the viewing surface 28 of the absorbent article 10 . the color of the first shade 42 and the second shade 44 of the colored portion 40 and the non - colored portion 50 are measured by the reflectance spectrophotometer according to the colors &# 39 ; l *, a *, and b * values . the l *, a *, and b * values are measured from the viewing surface 28 of the topsheet 25 inboard of the absorbent article &# 39 ; s periphery 12 . the color differences between the colored portion 40 and the non - colored portion 50 are measured at a first point 100 , a second point 110 , and a third point 120 on the viewing surface 28 of the topsheet 25 inboard of the periphery 12 of the absorbent article 10 . preferably , each one of the points 100 , 110 , and 120 resides fully within the periphery 12 of the absorbent core 20 . for example , the first point 100 is measured within the first shade 42 , the second point 110 is measured within the second shade 44 , and the third point 120 is measured within the non - colored portion 50 of the absorbent article 10 . the color differences are calculated using the l *, a *, and b * values by the formula δe =[( l * x · − l * y ) 2 +( a * x · − a * y ) 2 +( b * x − b * y ) 2 ] 1 / 2 . herein , the ‘ x ’ in the equation may represent points 1 , 2 or 3 . y may represent points 1 , 2 or 3 . x and y should never be the same two points of measurement at the same time . in other words , x ≠ y . where greater than two shades of a color ( s ) are used , the ‘ x ’ and ‘ y ’ values alternately include points of measurement in them also . the key to the δe calculation herein is that the ‘ x ’ and ‘ y ’ values should not stem from the same measured point on the viewing surface . in those instances where there is effectively no non - colored portion 50 within the confines of the measurement area , the ‘ x ’ values should flow from a point different in spatial relationship to the ‘ y ’ values , but within the confines of the absorbent core periphery ( see fig4 ). the difference in color ( δe *) between the first shade 42 and the second shade 44 should be at least 3 . 5 . the difference in color between the first shade 42 and the non - colored portion 50 is at least 6 . the difference in color between the second shade 44 and the non - colored portion 50 is at least 3 . 5 . preferably , the size of the colored portion 50 ranges from about 5 % to about 100 % of the viewing surface 28 of the topsheet 25 . also preferably , the first shade 42 of the colored portion 50 is positioned substantially centrally in relation to the second shade 44 of the colored portion 50 . however , so long as the shades are in proper spatial relationship to one - another such that the depth perception phenomena is created , any suitable positioning of the shades is foreseeable by one of skill in the art and are therefore acknowledged as suitable alternative embodiments of the invention . in one embodiment herein , the colored portion 40 may be an insert positioned between the topsheet 25 and the absorbent core 20 . in another embodiment , the colored portion 40 forms a part of the topsheet 25 . in yet another embodiment herein , the colored portion 40 forms a part of the absorbent core 20 whereby the colored portion 40 is viewable from the viewing surface 28 of the topsheet 25 . alternatively , the colored portion 40 may be a multi - layered insert positioned beneath the topsheet 28 . any topsheet material that allows the colored portion to be readily seen from the viewing surface 28 of the topsheet 25 is suitable . for example , formed film material , nonwovens , or combinations thereof are suitable . in an alternative embodiment herein , the absorbent article 10 provides a colored portion 40 wherein the viewing surface 28 of the topsheet 25 is substantially without a non - colored portion . by the term ‘ substantially without a non - colored portion ’ it is meant herein that color white is less than or equal to 5 % of the total surface area of the viewing surface 28 . fig3 provides an absorbent article wherein the first shade 42 is lighter and the second shade 44 is darker . also alternatively is an embodiment in which a color different from the color of the first shade 42 and the second shade 44 operates as a boundary between the two shades . in other words , this boundary 48 ( not shown ) rings the outer perimeter of the second shade 44 and separates the second shade 44 from the first shade 42 . the color scale values , utilized herein to define the darkness / lightness of the materials of the absorbent articles according to the present invention , is the widely accepted cie lab scale . measurements are made with a hunter color reflectance meter . a complete technical description of the system can be found in an article by r . s . hunter , ‘ photoelectric color difference meter ’, journal of the optical society of america , vol . 48 , pp . 985 - 95 , 1958 . devices specially designed for the measurement of color on the hunter scales are described in u . s . pat . no . 3 , 003 , 388 to hunter et al ., issued oct . 10 , 1961 . in general , hunter color “ l ” scale values are units of light reflectance measurement , and the higher the value is , the lighter the color is since a lighter colored material reflects more light . in particular , in the hunter color system the “ l ” scale contains 100 equal units of division . absolute black is at the bottom of the scale ( l = 0 ) and absolute white is at the top of the scale ( l = 100 ). thus in measuring hunter color values of the materials used in the absorbent articles according to the present invention , the lower the “ l ” scale value , the darker the material . the absorbent articles herein , and hence the materials of which the absorbent articles are made of , might be of any color provided that the l hunter value defined herein is met . colors can be measured according to an internationally recognized 3d solid diagram of colors where all colors that are perceived by the human eye are converted into a numerical code . the cie lab system is similar to hunter l , a , b an is based on three dimensions , specifically l *, a *, and b *. when a color is defined according to this system l * represents lightness ( 0 = black , 100 = white ), a * and b * independently each represent a two color axis , a * representing the axis red / green (+ a = red , − a = green ), while b * represents the axis yellow / blue (+ b = yellow , − b = blue ). fig4 shows the proper representation of the l , a , and b axes . a color may be identified by a unique δe value ( i . e ., different in color from some standard or reference ), which is mathematically expressed by the equation : δ e *=[( l * x · − l * y ) 2 +( a * x · − a * y ) 2 +( b * x − b * y ) 2 ] 1 / 2 ‘ x ’ represents the standard or reference sample which may either be a ‘ white ’ sample or a ‘ colored ’ sample , e . g ., one colored shade may be compared to another colored shade . it is to be understood that the tristimulus color values and δe * considered herein are those measured on the materials of interest ( e . g ., the colored and non - colored portions on the viewing surface of the topsheet disclosed herein ). the hunter color meter quantitatively determines the amount ( percent ) of incident light reflected from a sample onto a detector . the instrument is also capable of analyzing the spectral content of the reflected light ( e . g ., how much green is in the samples ). the hunter color meter is configured to yield 3 values ( l *, a *, b * and δe * which is total color ). the l * value is simple the percent of the incident ( source ) light that is reflected off a target sample and onto the detector . a shiny white sample will yield an l * value near 100 while a dull black sample will yield an l * value of about 0 . the a * and b * value contains spectral information for the sample . positive a * value indicates the amount of green in the sample . testing is conducted using a lab scan xe 45 / 0 geometry instrument to measure the different shaded options for the visual signal zone . the hunter color in cie lab scale 2 ° c . was measured on each pad in 3 portions . a 0 . 7 inch diameter port was used having a 0 . 50 inch area view , which was the largest size able to measure each zone discretely ; i . e ., this 0 . 5 inch area view is important for the purposes these measurements and should not be made smaller than the 0 . 5 inch area view prescribed . the instrument was calibrated using standard white and black tiles supplied by the instrument manufacturer . for measuring the l *, a *, and b * values for the invention herein , a standard , industry - recognized procedure is used . the topsheet color is measured using a reflectance spectrophotometer in accordance with method astm e 1164 - 94 , “ standard practice for obtaining spectrophotometric data for object - color evaluation ”. this standard method is followed but specific instrument settings and sampling procedure are given here for clarity . sample color is reported in terms of the cie 1976 color coordinate standard as specified in astm e 1164 - 94 and astm d2264 - 93 , section 6 . 2 . this consists of three values ; l * which measures sample “ lightness ”, a * which measures redness or greenness , and b * which measures yellowness or blueness . apparatus reflectance 45 °/ 0 ° hunter labscan xe , or equivalent spectrophotometer hunterlab headquarters , 11491 sunset hills road , reston va 20190 - 5280 tel : 703 - 471 - 6870 fax : 703 - 471 - 4237 http :// www . hunterlab . com . standard plate sandard hunter white tile source : hunter color . illumination type c standard observer 2 ° geometry 45 / 0 ° measurement angle port diameter 0 . 70 inch viewing area 0 . 50 inch ( and no smaller ) uv filter : nominal 2 . calibrate the spectrophotometer using standard black and white tiles supplied with the instrument according to manufacturer &# 39 ; s instructions before beginning any testing . 1 . unwrap , unfolded and lay the product or pad samples flat without touching or altering the color of the body facing surface . 2 . areas on the body - facing surface of the product should be selected for measurement and must include the following : the colored portion of the topsheet ; including the two or more shaded portions . any other portions of the topsheet above the absorbent core having a visibly or measurably different color from the first shaded zone . embossed channels and folds should not be included in zones of measurement as they may skew the proper results . measurements should not be made overlapping the border of two shaded portions . 2 . pads should be measured laying flat over the 0 . 70 inch aperture on the instrument . a white tile should be placed behind the pad . 3 . the pad should be placed with its long direction perpendicular to the instrument . 4 . measure the same zones selected above for at least 3 replicate samples . 3 . take the average l *, a *, b * for each zone measured . 4 . calculate δe * between different shaded portions and δe * between each shaded portion and the non - colored portion where the non - colored portion exists . the human sensitivity threshold for the lightness of a dark green color is a δe * of about 1 . 0 . for a dark green color , if only the a * and b * change , human sensitivity is a δe * of 2 . 4 . in the context of an absorbent article herein ( e . g ., a sanitary napkin ) it is highly likely that many people would not see a color difference if the δe * is less than 2 . this sensitivity is described in the following reference : “ the measurement of appearance ”, by hunter and harold , 2nd edition , 1987 , ( isbn 0 - 471 - 83006 - 2 ). chapter 4 of hunter &# 39 ; s book describes human color sensing and chapter 9 is about color scales . by making side - by side comparison , humans can differentiate up to 5 to 10 million different colors . in the 1940s , a researcher named macadam did human chromaticity discrimination experiments . he found the thresholds of sensitivity and showed these depend on the color . later work by brown and macadam came up with a logarithmic lightness dimension scale for human sensitivity to go with the earlier color scale . based on the reduction to practice of the invention , experimentation and the foregoing work by brown and macadam , it has been found herein that a δe ≧ 3 . 5 is the preferred range to effect proper differentiation between the shades that provides the proper appearance of depth . however , where the δe is as small as about 1 and still operates to provide a perception of depth between the shades , this δe is also contemplated and included herein . an example where δe may be between at last two shades of one or more colors may be found in an alternative embodiment that provides a multi - color and / or shade gradient of a color across the viewing surface of the absorbent article . chart i sample number topsheet type colored options δe * 23 δe * 12 δe * 13 1 formed film two - tone inner / outer 6 . 10 10 . 83 16 . 86 color 2 formed film one - tone color 0 . 25 8 . 60 8 . 80 3 non - woven one - tone color 0 . 22 10 . 63 10 . 81 4 non - woven two - tone inner / outer 5 . 98 11 . 03 16 . 92 color 5 formed film two - tone light outer 10 . 01 2 . 88 12 . 80 color / inner dark color 6 formed film two - tone medium outer 7 . 51 6 . 37 13 . 61 color / inner dark color 7 formed film two - tone darker outer 5 . 60 19 . 16 14 . 22 color / inner dark color 8 formed film two - tone ( secondary 4 . 58 6 . 00 8 . 06 topsheet colored outer color )/( core colored dark color ) 9 formed film one - tone outer color 0 . 21 8 . 90 8 . 84 as has been noted previously , the difference in color between the first shade and the second shade should be at least 3 . 5 . the difference in color between the first shade and the non - colored portion is at least 6 . the difference in color between the second shade and the non - colored portion is at least 3 . 5 . through experimentation and reduction to practice of the invention , it has been determined that the preferred creation of depth perception happens at about and above these set parameters . for products substantially not having a non - colored portion within the measurement zone ( i . e ., a gradient or fully colored product ), the above criteria for the shaded portions ( i . e ., δe *≧ 3 . 5 ) remains the preferred standard . chart i above clearly shows the δe * s obtained between multi - tone ( e . g ., two tone ) and single tone signals . formed films and nonwovens useful for the invention herein are those which will allow the sufficient penetration of light therethrough such that the shaded portions may be clearly discerned and such that such discernment produces the depth perception effect . the color may be any suitable color fitting within the parameters herein for δe * between colored portions and non - colored portion ( where it exists ). for example , the colors green , blue , red , yellow , orange , purple and any other color within the color spectrum are suitable for the purposes described herein . sample nos . 1 and 2 are clearly distinct in their δe * 23 . specifically , the δe * 23 ( which is 6 . 10 ) is greater than 3 . 5 . this δe 23 indicates that there is a perceptible difference in color or lightness / darkness between the two points of measurement ; i . e ., between the second shaded portion and the non - colored ( or white ) portion ( see fig4 ). as noted above for human perception , sample no . 2 &# 39 ; s δe * 23 of 0 . 25 would not be perceptible to the human eye . this indicates that the signal is only a one or single tone signal ( i . e ., color portion ). all documents cited in the detailed description of the invention are , are , in relevant part , incorporated herein by reference ; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention . while particular embodiments of the present invention have been illustrated and described , it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention . it is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention .
the absorbent article provides a signal viewable from the top surface of the absorbent article which gives a perception of depth within the absorbent article . this creation of depth perception is accomplished by the use of at least two tones within a color and / or by the use of multiple tones and multiple colors operating together to create a perception of depth within the absorbent article .