hereinafter , embodiments of the present invention are described with appropriate reference to the drawings . the invention is not limited to descriptions given below . fig1 ( a ) and 1 ( b ) are each an external view of a nucleated tablet 1 according to the present invention . the right view thereof is a sectional view taken on line a - a of the left view thereof . the nucleated tablet 1 is composed of an outer shell 2 and an inner nucleus 3 . the shape and size of the nucleated tablet 1 are not particularly limited ; however , it is sufficient that the nucleated tablet 1 contains chemical agents necessary for cleaning cls ( one set of two cls ) one time . fig2 ( a ) to 2 ( c ) are views illustrating a method of using a cl cleaning preparation according to the present invention . first , cls 8 are set to a lens case upper part 7 ( fig2 ( a )). next , a nucleated tablet 1 is taken out from a nucleated tablet package 9 , and then put into a lens case lower part 4 . from a dissolving liquid container 5 , a predetermined volume of a dissolving liquid 6 is collected into the lens case ( fig2 ( b )). it is preferred to mark a scale in the lens case lower part 4 in order to indicate the volume of the dissolving liquid 6 to be collected . next , the lens case upper part 7 is fitted to the lens case lower part 4 ( fig2 ( c )). at this time , it is preferred to adjust the volume of the dissolving liquid 6 to cause the whole of the cls 8 to be immersed in the dissolving liquid 6 . in this state , the lens case is allowed to stand still for 4 hours or more . the outer shell 2 of the nucleated tablet 1 is gradually dissolved in the dissolving liquid by foaming effect based on a carbonate and an organic acid ( foaming caused by carbon dioxide ), so that the dissolving liquid 6 is gradually colored to a color from yellow to brown by effect of an iodine - based bactericide . the iodine - based bactericide and a surfactant can be evenly dissolved in the dissolving liquid 6 by the foaming effect even when a stirring operation is not made at all . with respect to the outer shell of the nucleated tablet 1 , it is preferred to adjust the pressure for making a tablet , the amount of a disintegrating agent , or some other factor to dissolve the outer shell completely in a period less than 5 minutes and disinfect the cls with the iodine - based bactericide . by coating the surface of the inner nucleus ( coating the surface for extended release ) with hydroxypropylcellulose ( hpc ), hydroxypropylmethylcellulose ( hpmc ) or hydroxyethylcellulose ( hec ), the inner nucleus can be also kept not to be immediately dissolved even when the outer shell is dissolved . this manner makes it possible to maintain sufficiently a period for disinfecting the cls with the iodine - based bactericide . it is preferred to adjust the period until the inner nucleus starts to be dissolved in accordance with the concentration of the iodine - based bactericide . when the outer shell has been dissolved , the inner nucleus starts to be dissolved . the inner nucleus also contains a carbonate and an organic acid incorporated thereinto ; thus , the incorporated components can be evenly dissolved in the dissolving liquid even when no stirring operation is made . since the inner nucleus contains a neutralizing agent for the iodine - based bactericide incorporated thereinto , the iodine - based bactericide is gradually neutralized to the accompaniment of the dissolution of the inner nucleus . following the neutralization , the dissolving liquid 6 is gradually made colorless . a basic function of the inner nucleus is the release of the neutralizing agent , thereby attaining the neutralization ( reduction ) of the iodine - based bactericide . however , further incorporation of a surfactant makes it possible to remove stains based on a protein or fat on the surface of each of the cls . additional incorporation of a protease into the inner nucleus also makes it possible to remove the protein on the surface of the cl effectively . in order to adjust , at this time , the ph of the dissolving liquid to an optimal ph for the protease , it is preferred to adjust the ph of the dissolving liquid 5 or incorporate a ph adjustor into the inner nucleus . with respect to the inner nucleus of the nucleated tablet 1 , it is preferred to adjust the pressure for making a tablet and the amount of a disintegrating agent to dissolve the inner nucleus completely in a period less than 30 minutes , and finish the neutralization of the iodine - based bactericide , and the cleaning of the surface of each of the cls . after the cleaning operation , the cls can be taken out from the lens case upper part 7 , and be worn as they are . however , when the inner nucleus contains a surfactant and / or a protease incorporated thereinto , it is preferred that after the cleaning operation the dissolving liquid 6 is thrown away , and subsequently the cls are rinsed with a new dissolving liquid inside the lens case . it is recommended that a cl is disinfected every day . according to the cl cleaning preparation and cl cleaning method of the present invention , only by setting a dissolving liquid , a nucleated tablet , and cls inside a lens case before sleeping , and then leaving these members as they are , the disinfection and cleaning of the cls are completed at the time of rising up and thus , the cl can be immediately worn . for the cl cleaning preparation and cl cleaning method of the present invention , a dissolving liquid is necessary for dissolving the nucleated tablet for cl cleaning . the dissolving liquid preferably has an osmotic pressure of about 100 to 400 mosm , and more preferably has an osmotic pressure of about 200 to 300 mosm . the component ( s ) thereof is / are not particularly limited . the dissolving liquid is not limited about the type thereof as far as the liquid is a liquid usable as a cl cleaning liquid , for example , a physiological saline solution , a phosphoric acid solution or a boric acid solution . into the nucleated tablet for cl cleaning of the present invention and / or the dissolving liquid may be optionally incorporated a buffer agent , an tonicity agent , or a thickening agent as far as the sterilizing effect of the iodine - based bactericide is not hindered and any significant effect is not produced onto living body ( eyeball ) and the physical properties or shape of a cl . the buffer agent is used to stabilize the ph of the dissolving liquid . the buffer agent may be a buffer agent used generally for a cl cleaning solution or for an ophthalmic preparation . it is preferred to use , for example , ( 1 ) a phosphoric acid - based buffer agent , such as sodium monohydrogenphosphate , sodium dihydrogenphosphate , potassium monohydrogenphosphate , or potassium dihydrogenphosphate ; ( 2 ) a boric acid - based buffer agent , such as boric acid , or sodium borate ; or ( 3 ) a tris buffer agent , such as trisaminomethane and diluted hydrochloric acid , or trismalate and a diluted sodium hydroxide solution . it is preferred to incorporate the buffer agent into the nucleated tablet for cl cleaning and / or the dissolving liquid in such a manner that when the nucleated tablet for cl cleaning is dissolved in the dissolving liquid , the concentration thereof ranges from 0 . 05 to 1 . 0 % by weight . when the nucleated tablet for cl cleaning is dissolved in the dissolving liquid , it is preferred to set the ph of the resultant solution into range of 5 to 8 . if the ph is in an acidic range having a ph less than 5 or in an alkaline range having a ph more than 8 , eye irritancy or ophthalmopathy may be caused . thus , the ph should be avoided . the tonicity agent is used to adjust the osmotic pressure of the dissolving liquid . the tonicity agent may be a tonicity agent used generally for a cl cleaning solution or an ophthalmic preparation . it is preferred to use , for example , ( 1 ) an alkali or alkaline earth metal salt , such as sodium chloride , potassium chloride or magnesium chloride ; or ( 2 ) a saccharide , such as glucose , mannitol , sorbitol , xylitol , or dextran . these tonicity agents may be used alone or in combination of two or more thereof . when the nucleated tablet for cl cleaning is dissolved in the dissolving liquid , it is preferred to adjust the concentration of the tonicity agent ( s ) into the range of 0 . 5 to 5 . 0 % by weight . by the adjustment of the concentration of the tonicity agent ( s ), the osmotic pressure generated when the nucleated tablet for cl cleaning is dissolved in the dissolving liquid is adjusted into the range preferably from about 100 to 400 mosm , and more preferably from about 200 to 300 mosm . the thickening agent is used to adjust the viscosity of the dissolving liquid . the thickening agent may be a thickening agent used generally for a cl cleaning solution or an ophthalmic preparation . it is preferred to use , for example , ( 1 ) a polyol , such as glycerin , ethylene glycol , propylene glycol , polyethylene glycol or polyvinyl alcohol ; or ( 2 ) a saccharide , such as trehalose , sucrose , carboxymethylcellulose , hydroxyethylcellulose , or hydroxylpropylmethylcellulose . the concentration of the thickening agent is not particularly limited . when the nucleated tablet for cl cleaning is dissolved in the dissolving liquid , it is preferred to set the agent concentration into the range of 0 . 05 to 5 . 0 % by weight . into a 50 - ml vial was put a mixture of 3 g of a povidone iodine powder , 72 mg of each surfactant shown in table 1 , and 360 mg of tartaric acid . this vial was closed , and stored in a thermostat at a temperature of 40 ° c . with respect to each of the samples , the effective iodine remaining percentage in the povidone iodine powder was measured after 0 , 3 , 7 and 15 days . the effective iodine remaining percentage (%) was calculated by determining quantitatively the effective iodine quantities before and after storages in accordance with the effective iodine quantitative determination method described in item “ povidone iodine ” in japanese pharmacopoeia . fig3 is a graph showing measurement results of the effective iodine remaining percentage . for polyethylene glycol 4000 , the effective iodine remaining percentage was largely lowered as compared with the other surfactants . for each of sodium lauroylsarcosine , polyethylene glycol 6000 , and polyoxyethylene ( 196 ) polyoxypropylene ( 67 ) glycol , the effective iodine remaining percentage after 15 days was close to 100 %. for polyoxyl 40 stearate , the percentage was about 90 %. each nucleated tablet was produced which contained components shown in table 2 . a method for producing the tablet was specifically as described below . in table 2 , respective incorporated quantities denote incorporated quantities per tablet . first , out of its inner nucleus components , the following were collected : dry sodium carbonate , sodium chloride ( partial volume ), d - mannitol ( partial volume ), bioprase conc ( generic name : subtilisin , manufactured by nagase chemtex corporation ), and polyoxyethylene polyoxypropylene glycol ( partial volume ). the collected components were made into the form of granules . the granules , which were white , were used as first granules . next , out of the inner nucleus components , the following were collected : tartaric acid , sodium chloride ( the balance ), d - mannitol ( the balance ), and polyoxyethylene polyoxypropylene glycol ( the balance ). the collected components were made into the form of granules . the granules , which were white , were used as second granules . a predetermined amount of the first granules was mixed with a predetermined amount of the second granules , and the mixture was made into naked tablets ( 66 mg per tablet ) in accordance with the item of pharmaceutical preparation general rules in japanese pharmacopoeia . the naked tablets were coated ( coated for extended release ) with hypromellose in a usual manner to prepare inner nuclei . separately , povidone iodine , dry sodium carbonate , tartaric acid , and d - mannitol , which were outer shell components , were collected . these components were made into a granular form while macrogol 6000 ( drug listed in japanese pharmacopoeia ) was added to the components . the granules , which were slightly yellowish - brown , were used as third granules . a machine for making a nucleated tablet was used to make the inner nuclei and the third granules into nucleated tablets as nucleated tablets of each of examples 1 to 4 . for the nucleated tablets , their outer shells were completely dissolved in 3 minutes when 8 ml of a boric acid buffer solution was used as a dissolving liquid . for the nucleated tablets , after the dissolution of the outer shells , the inner nuclei were completely dissolved . asa result , povidone iodine was neutralized and the dissolving liquid turned transparent and colorless . a production of nucleated tablets was attempted by conducting operations entirely identical with those in example 1 except that polyoxyethylene ( 196 ) polyoxypropylene ( 67 ) glycol was used as a lubricant for their outer shell in the same amount . when the nucleated tablets were made , a sticking phenomenon was frequency caused . thus , obstacles were slightly caused to the mass production of the nucleated tablets . a production of nucleated tablets was attempted by conducting operations entirely identical with those in example 1 except that polyoxyl 40 stearate was used as a lubricant for their outer shell in the same amount . when the nucleated tablets were made , a sticking phenomenon was frequency caused . thus , obstacles were slightly caused to the mass production of the nucleated tablets . a production of nucleated tablets was attempted by conducting operations entirely identical with those in example 1 except that sodium lauroylsarcosine was used as a lubricant for their outer shell in the same amount . when the nucleated tablets were made , a sticking phenomenon was frequency caused . thus , obstacles were slightly caused to the mass production of the nucleated tablets . the nucleated tablet for cl cleaning of the invention and the cl cleaning preparation thereof , which contains this nucleated tablet , and the cl cleaning method thereof are useful as a cl cleaning preparation and a cl cleaning method .