Abstract:
A precise critical temperature indicator is applied to small products requiring refrigeration or freezing to control the operation of a temperature sensor built into an integrated structure of a single body. A method for manufacturing said precise critical temperature indicator, wherein a plurality of development medium members and a plurality of development material members are opposed to each other, and blocking members are interposed therebetween to support the development medium members and the development material members separately from each other, the development medium members are provided with paths for moving development materials, or paths for movement of development materials can be shortened to adjust speed, and an indication unit is arranged to indicate the state of the development materials at an end or central portion of the development medium when the development materials are exposed to a critical temperature for a predetermined time period.

Description:
This is a 35 U.S.C. §371 application of, and claims priority to, International Application No. PCT/KR2009/006088, which was filed on Oct. 21, 2009, and which claims priority to Korean Patent Application No. 10-2008-0104758, which was filed on Oct. 24, 2008, and No. 10-2009-0065770, which was filed on Jul. 20, 2009 and the teachings of all the applications are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a critical temperature indicator, in particular to a precise critical temperature indicator to be easily adapted to relatively smaller storing products necessary for refrigeration or freezing and to control a temperature sensor built into an integrated structure of a single unit therein and a manufacturing method therefor. 
     BACKGROUND TECHNOLOGY 
     There has been a critical temperature indicator of a typical prior art that can be obtained as a commercial name “MONITOR MARK™” of 3M. 
     As shown in  FIG. 1 , the critical temperature indicator  10  includes an indicating material or development material layer  11  diffused with being reacted or melted at or above a predetermined temperature and a wicking member or development medium layer  12  absorbing a solvent from the development material layer  11 . The development material layer  11  is referred to a temperature sensing layer mixed with ink and fatty acid or paraffin, and the development medium layer  12  is made of absorbing papers, non-woven fibers, etc. a barrier or isolation layer  13  is placed between the development material layer  11  and the development medium layer  12 . A first major sheet or supporting layer  14  and an opposing second major sheet or both sided-adhesive tape  15  are in turn arranged on the lower portion of the development material layer  11 . An indicating layer  16  includes indication windows to be arranged on the development medium layer  12 , in which the indication windows includes larger indicating windows  16 ′ and smaller indication windows  16 ″ formed in a longitudinal direction thereon. A transparent layer  17  is positioned on the right of the indication layer  16 . 
     On the other hand, the development medium layer  12 , the indication layer  16  and the transparent layer  17  are provided with cutting portions  18  having the same size, respectively, on the same position of their one side. The temperature indicator  10  further includes a supporting layer  14  attached to the both sided-adhesive tape  15 , on which the development material layer  11  and the development medium layer  12  are arranged on the supporting layer  14  with the isolation layer  13  positioned there between. Then, the transparent layer  17  is positioned on the indication layer  16  to finish the assembly of the temperature indicator  10 . 
     Therefore, the temperature indicator  10  is attached to a predetermined position of a refrigeration product through the adhesive portion of the both sided-adhesive tape  15 , the cutting portion  18  is removed there from and the isolation layer  13  is drawn out between the development material layer  11  and the development medium layer  12  to contact with each other. 
     Thereafter, the temperature indicator  10  begins to be operated in a manner that the development material  11  including a fluid of fat or paraffin with a pigment ink is melted, infiltrated into the development medium layer  12  and immigrated along the lengthwise thereof to indicate the storage state of the products through the indication windows  16 ′ and  16 ″. 
     But the temperature indicator has disadvantages in that the resultant product size becomes relatively bigger due to the mitigation of the development material in a longitudinal direction, requires a larger power of attention for removing the cutting layer between the development material layer and the development medium and layer. It is difficult to automate the manufacturing of the product. Since the development material is easily exposed to the air atmosphere without being sealed, it must be refrigerated or cooled for over one to two hours below a melting point thereof before being used. If it is used and melted at the state exposed to a normal temperature, some fluid of the development material adheres to the isolation layer when the isolation layer is removed. 
     Particularly, the development material is slowly migrated as being gradually far away from the starting point. For it, such like strip type of the temperature indicator has a disadvantage in that a error range of the temperature indication time is relatively greater. 
     Another typical prior art of U.S. Pat. No. 7,232,253 (US Unexamined Publication No. 2004/0240324 published on Dec. 2, 2004) discloses “A time indicator and method of manufacturing same”. The time indicator comprises a first reservoir, a migration medium and activating means for bringing liquid from the first reservoir in contact with the migration medium so that after activation the liquid migrates through the migration medium producing a color change therein. The activating means comprises a second reservoir connected between the first reservoir and the migration medium whereby after activation the liquid travels relatively rapidly from the first reservoir to the second reservoir and then migrates relatively slowly along the length of the migration medium over time. 
     The patent has some characteristics in that it can measure the time elapse according to its operation and make a visible indication of the product life span. A pressure-rupturable seal or weak seal is formed to isolate a liquid conduit, as the activating means (of a convex dish type) that is constituted to be broken as the first reservoir is pressed with a predetermined amount of force. But the weak seal causes the temperature indicator to be mal-functioned due to the carelessness of users in use. Also, since it must be constructed so that liquid passing through the liquid conduit is contacted with the migration medium, the time indicator has disadvantages in that it is difficult to mass-produce the product due to a stringent configuration such as the weak seal, etc. and to store an enormous volume of products in one unit due to the convex dish type portion. 
     Another typical prior art of U.S. Pat. No. 6,957,623 discloses “A critical temperature indicator” enabling a visual, irresolvable indication under a critical temperature. The critical temperature indicator includes a transparent housing and a temperature sensitive transformable material operably contained within the transparent housing, which is a mixture of a stabilizer including water, latex, nucleating agent that is preferably ice nucleating active (INA) microorganism. The mixture is translucent prior to exposure of a predetermined temperature and is transformed at a predetermined temperature to render a substantially consistent opaque material, thereby precluding visibility there through and providing a sure visual sign that the indicator has been subjected to the predetermined temperature. Herein, the mixture of the stabilizer has an inherent color and is sealed in the form of a capsule and constituted as means for detecting the thawing and/or refrigeration/freezing of a product, but it has a problem in showing the state transformation of a system. In other words, it is not sure that the critical temperature indication of the system is the exact information of the management state from a time activated under the critical temperature or a time that it is possible to be exposed to a critical temperature, for example from a delivering time and a transformable time of a product having the system. 
     In order to resolve these problems, another typical prior art of International Patent Application WO/2007/148321 published on Dec. 27, 2007 discloses “An irreversible coolness indicator” which is a type of a critical temperature indicator. The critical temperature indicator comprises a sealed housing having at least one surface, which is transparent and contains a suspension if inorganic monoparticles are suspended in a liquid medium, wherein the suspension undergoes an irreversible detectible change in optical characteristics upon freezing of the liquid medium due to aggregation of the nanoparticles, and wherein the device is provided with means for association thereof with a product, whereby the temperature-threshold indicator device serves to determine whether the product has been exposed to an environment of predetermined coldness. 
     The critical temperature indicator has features in the simple configuration and the composition of the suspension showing the state transformation at a predetermined color according to a temperature for the refrigeration/thawing detection. But, the critical temperature indicator has some disadvantages in that it is difficult to lower the high manufacturing cost due to the suspension composition, to automate the mass-production thereof and especially to confirm a time to be exposed to the coldness environment. In other words, the critical temperature indicator also fail to show the management states of an activating time under a critical temperature and a time possibly exposed to a critical temperature, whereby the management state from a delivery time to a transformable time of a product cannot be confirmed. 
     Considering these points, it is preferable if a critical temperature indicator enable the confirmation of a use time point and has an exact operating mechanism there from, and the management state from a delivery time to a transformable time of a product is confirmed. 
     It is also preferable if a critical temperature indicator reduces the error range of a time exposed to a critical temperature from a time that the development material is first developed in a lengthwise in a strip type of a critical temperature indicator. 
     It is also preferable if a critical temperature indicator is convenient for the use, adapted to small refrigeration and freezing products and constructed as a simple configuration enabling the mass-production therefor. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Technical Problem to be Solved 
     A main object of the invention is to provide a precise critical temperature indicator adapted to smaller refrigeration and freezing products without any restriction and for enabling the operating control of a sensor having an integrated configuration of a single body that a development medium member and a development material member are simply separated from or contacted with each other and manufacturing method therefor. 
     Another object of the invention is to provide a precise critical temperature indicator suitable for relatively smaller refrigeration and freezing products and for enabling the operating control of a temperature sensor and indicating the exposure state to a critical temperature, in which the temperature sensor includes at least one substrate divided on a single flat plate, a plurality of development medium members and a plurality of development material members properly put on the substrate and another portion constituted as an isolation member or a handle portion to separate the development medium member and the development material member from each other and manufacturing method therefor. 
     Another object of the invention is to provide a precise critical temperature indicator adapted to relative smaller refrigeration and freezing products without any restriction and for precisely controlling the migration of a development material from both sides of a development medium member in operating, in which the upper development medium member and the lower development material member with their both ends contacted on a mediate member are sealed together with a separation sheet being arranged there between to prevent their contact and manufacturing therefor. 
     Another object of the invention is to provide a precise critical temperature indicator including a plurality of temperature sensors which comprises a plurality of development medium members and a plurality of development material members with a separation sheet being arranged there between, both ends of which are contacted on a mediate member, for coupling the temperature sensors with an upper indication portion and a lower base portion supporting them and for enabling a mass production or assembly thereof. 
     Means to Resolve Problems 
     According to the invention, a precise critical temperature indicator and manufacturing method therefor is as follows: a plurality of development medium members and a plurality of development material members face to each other and a separation member is mounted therebetween to support the separation state of the development medium members and the development material members, the development medium member enables the speed adjustment in a manner to form and/or shorten a migration path thereon and an indication portion for indicating the state of the development material at the end or center of the development medium member and for enabling the mass-production of a plurality of temperature sensors and. 
     According to one embodiment of the invention, a precise critical temperature indicator comprises a single substrate divided into three portions including a first portion forming an indicating window at one portion thereof, a second portion extended from the first portion and a third portion detachably connected to the second portion; and a development medium member and a development material member each arranged on the first and second portions, so that the third portion including a handle portion to be cut out therebetween is folded thereon to form a temperature sensor, thereby removing the handle portion to contact the development material member and the development medium member with each other to enable the operation control of a system. 
     The single substrate includes the first portion provided with the development medium member, the second portion formed as a base plate that is provided with the development material member, a connection portion folded between the third portion and the second portion and the handle portion including a cutting line extended into the second portion, cut in a smaller width and then cut along the whole length in the opposite direction except for second connecting portions, thereby folding the third portion onto the base plate with the development material member and then the first portion with the development medium member thereon to integrate them into a single body. 
     The temperature sensor includes the development medium member on the first portion, the development material member and the third portion placed therebetween, in which the handle portion on the third portion is removed to contact them to each other and then according to the time elapse a predetermined color of a dye applied to the development material migrating along the development medium member is appeared on the indicating window, thereby enabling the critical temperature indication. 
     The development medium member includes a development medium in the threaded form of a circle, triangle or rectangular, etc. and a protection film made of vinyl, etc. to protect the development medium. 
     The development material member includes a rectangular development material and a protection film made of vinyl, etc. to protect the development material. 
     According to one embodiment of the invention, a manufacturing method of a precise critical temperature indicator comprises steps of dividing, scoring and perforating for cutting to form a plurality of single substrates on a single sheet, in which the single substrate is divided into three portions divided into three portions including a first portion forming an indicating window at one portion thereof, a second portion extended from the first portion and a third portion detachably connected to the second portion; loading the development medium member and the development material member, respectively, on two portions of the single substrate and positioning the other portion therebetween to separate them from each other to construct a temperature sensor; and inserting the third portion between them, thereby removing the handle portion to contact the development material member and the development medium member with each other to enable the operation control of a system. 
     According to another embodiment of the invention, a precise critical temperature indicator comprises a temperature sensor including an upper development medium member mounted on an immediate member, both ends of which meet each other to enable the development material to be migrated in both directions, a lower development material member having a development material on one side portion and an isolation sheet positioned between the upper development medium member and the development material member; a temperature indicating window receiving the development medium member, one end of which is projected from one side thereof; and a base portion positioned under the isolation sheet and sealed to enclose the development material therein. 
     According to another embodiment of the invention, a manufacturing method of a precise critical temperature indicator comprises steps of preparing an indicating unit including a plurality of indicating windows in the form of any one of a case and a flatness made of a synthetic resin film; preparing a development medium unit including an immediate member serving as a supporting piece which is expended in a lengthwise and a plurality of development medium members including development mediums of a plurality of porous films, both ends of which is folded to meet each other; preparing a sheet unit coupled with an indicating portion with a size corresponded or almost equal thereto; preparing a base unit to cooperate with a plurality of development medium members on the sheet unit positioning the development material members in a one to one correspondence on each of a plurality of base portions to cooperate with a plurality of development medium members on the sheet unit; positioning an isolation sheet member including a plurality of single isolation sheets between the development medium unit and the development material unit; positioning the development material unit and the isolation sheet member combined with each other on the base unit; loading the development medium units including the immediate member on the combined units; and sticking the indication unit and the base unit to each other and then welding/sealing them together using a high heat or a high frequency for the mass-production of a system. 
     The manufacturing method of the precise critical temperature indicator further comprises a step of forming a configuration of a double zipper in that both ends of the base unit and the indication unit in are combined with each other. 
     Therefore, the precise critical indicator is made cutting the temperature sensors one by one after combining the indicating unit that is integrated with a plurality of temperature sensors and the base unit with each other. The temperature sensor is operated by removing the isolation sheet between the development medium member and the development material member and indicates/warns the abnormal state of products at an exact elapse time point, as it is exposed to a temperature over the critical one and senses the critical temperature of the product. 
     Effect of the Invention 
     The invention can be constructed in a compact configuration and adapted to a smaller refrigeration and freezing product and can keep a development medium member and a development material member separated from each other at ordinary times. Furthermore, the invention can precisely and uniformly control the critical temperature indication heightening the migration speed of the development material 
     Also, the invention can easily not only contact the development medium member and the development material member to each other by removing the isolation portion or even only a part thereof but also need not cool the development material member at below the critical temperature before use. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view illustrating one example of a prior art in detail. 
         FIG. 2  is an exploded perspective view illustrating a critical temperature indicator provided with a temperature sensor in detail according to one embodiment of the invention. 
         FIG. 3  is a plane perspective view illustrating the assembly state of a critical temperature indicator provided with a temperature sensor according to one embodiment of the invention. 
         FIGS. 4 ,  5 ,  6  and  7  are plane views illustrating various forms of development material, dye applied positions and an indicating window position. 
         FIGS. 8 ,  9 ,  10 ,  11  and  12  are cross-sectional views illustrating a method for manufacturing a critical temperature indicator provided with a temperature sensor in large quantities in due order according to one embodiment of the invention. 
         FIG. 13  is a plane view illustrating an upper portion of a precise critical temperature indicator according to other embodiment of the invention. 
         FIG. 14  is a cross-sectional view illustrating the assembly state of a precise critical temperature indicator according to other embodiment of the invention. 
         FIG. 15  is a detailed and exploded perspective view illustrating a precise critical temperature indicator according to other embodiment of the invention. 
         FIGS. 16 , A, B, C and D are views illustrating a method of mass-manufacturing a precise critical temperature indicator through the assembly according to another embodiment of the invention. 
         FIG. 17  is an exploded perspective views illustrating a method of mass-manufacturing a precise critical temperature indicator through its assembly according to another embodiment of the invention. 
     
    
    
     BRIEF DESCRIPTION OF IMPORTANT DRAWING REFERENCES 
     
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                 100: 
                 Precise critical 
                 102: 
                 First portion 
               
               
                   
                 temperature indicator 
                 121: 
                 Third portion 
               
               
                 111: 
                 Second portion 
                 112, 250: 
                 Development material 
               
               
                 104, 
                 Development medium 
                   
                 member 
               
               
                 240: 
                 member 
                 122: 
                 Second connecting portion 
               
               
                 108: 
                 First connecting portion 
                 220: 
                 Indication portion 
               
               
                 123: 
                 Cutting line 
                 260: 
                 Indication unit 
               
               
                 280: 
                 Sheet unit 
                 200: 
                 Development material unit 
               
               
                 290: 
                 Development medium unit 
                   
                   
               
               
                 210: 
                 Base unit 
               
               
                   
               
             
          
         
       
     
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention will be explained in detail with reference to accompanying drawings, which has a configuration integrated into a single body. 
     According to the invention, as shown in  FIGS. 2 and 3  a precise critical temperature indicator  100  includes a single substrate  101  that is a single flatness plate. The single substrate  101  includes 3 portions foldable to each another. Among them a first portion  102  includes an indication window  103  formed adjacent to one edge or at a predetermined position of the center and a development medium member  104  having a predetermined area which is positioned in a side by side to the first portion  102 . A liposoluble dye  107  is applied adjacent to one edge of a first protection film  106 . 
     A second portion  111  acts as a base plate on which a development material member  112  is positioned. A second connecting portion  122  connects the second portion  111  to a third portion  121 . The development material member  112  includes a development material  113  made of non-woven fibers and absorbing papers and a second protection film  113  made of vinyl, etc. to protect the development material  113 . 
     The third part  121  includes a handle portion  124  extended in a relative smaller width by a predetermined length from one edge of the second portion  111  there into, on which a cutting line is formed along the whole length thereof. The handle portion  124  is positioned at the center of the third portion  121  and includes third connecting portions  125  not cut at one side thereof to be connected to the third portion  121 . 
     In other words, there is scored a first connecting portion  108  between the first portion  102  and the second portion  111 . There is scored the connecting portion  122  between the second portion  111  and the third portion  121  to form a foldable portion. Therefore, a temperature sensor  110  is configured as follows: 
     The temperature sensor  110  comprises the development medium member  104 , the development material member  112  and the indication window  103 . The development material  113  loaded on the development material member  112  is composed of a solvent containing fatty acid or fluid paraffin, which can be mixed with an ink having dye of a predetermined color if necessary. The development material  113  is dissolved at over a critical temperature of the surroundings, and the dissolved fluid is migrated along the development medium  105  as contacted with the front end thereof. At that time, the development medium  105  begins to manifest the color of a fatty dye  107 , as the solvent of the development material  113  migrates and approaches. According to the time elapse at over a critical temperature, the manifested place is moved. Then at a predetermined delaying time, the manifested color is identified at the indication window  103  to check out the current state of the refrigeration or freezing product. 
     The development medium member  104  includes a first protection film  106  made of a transparent PTP known as Press Through Pack or vinyl, etc. to protect parts of the development medium  105  except for a front end portion thereof. Also, the development medium member  104  includes an extension portion  109  extended in a concentric circle or a threaded form from one end thereof to secure a predetermined length. The extension portion  109  may be the development medium  105  in the form of a circle, triangle or rectangular or serpentine type and many shapes as shown in  FIGS. 4 ,  5 ,  6  and  7 . 
     Also, the development medium member  104  includes a fatty dye on the upper portion thereof, so that the indication window  103  enable the manifestation color to be identified at a predetermined delaying time, as the development material  113  not dyed and contacted with the front end portion of the development medium  105  is solved and migrated along the extension portion  109 . 
     On the other hand, it is noted that the single substrate  101  is configured to position the development medium member  104  on the first portion  102  and the development material member  112  on the second portion  111 . 
     As shown in  FIGS. 8 ,  9 ,  10  and  12 , a precise critical temperature indicator  100  is to assembly a plurality of single substrates divided into three portions on a single sheet to be integrated into a single body for a mass-production. 
     As shown in  FIG. 8 , a single sheet  150  is made of a soft material such as PVC or PE etc., on which a plurality of single substrate  101  are formed. The single sheet  150  is scored, cut and perforated at once for each work adapted to a plurality of single substrates. Therefore, the work means the forming of an indication window  103  on a first portion  102 , a first connection portion  108  between the first portion  102  and a second portion  111 , a second connection portion  122  between the second portion  111  and a third portion  121  and a handle portion  124  having a cutting line  123  on the third portion  121 . 
     As shown in  FIG. 9 , the single sheet  150  includes a plurality of single substrates  101 , on each of which the development medium  105  on the first portion  102  and the development material  113  on the second portion  111  are arranged. 
     As shown in  FIG. 10 , a first protection film  106  and a second protection film  114  are respectively coated on the development medium  105  in the first portion  102  and the development material  113  in the second portion  111  which are arranged on each of a plurality of single substrates  101  of the single sheet  150 . Therefore, the temperature sensor  110  is assembled and mounted on the single substrate  101 . 
     As shown in  FIG. 11 , as the temperature sensor  110  is mounted, the third portions  121  on the single substrates  101  connected with each another are folded on the second portion  111 . 
     As shown in  FIG. 12 , with the temperature sensor  110  being mounted, the third portions  121  on a plurality of single substrates  101  are folded on the second portion  111 , and the first portion  102  is folded on the third portion  121 . 
     With the temperature sensor  110  being mounted, a plurality of single substrates  101  connected with each another is welded along their edges using a high frequency and cut to complete the assembly of the precise critical temperature indicator  100 . 
     As described above, the precise critical temperature indicator  100  can be constructed at a size below 20 mm and fixed on even a little refrigeration or freezing products using both-sided adhesive tape. The temperature sensor  110  is operated in a manner to pull the handle portion  124  outside in one direction to contact the front end of the development medium  105  with the development material  113 . As the development material  113  is solved at over a critical temperature of the surroundings in this state, the dissolved fluid is developed along the extension portion  109  of the development medium member  194 . At that time, the dye applied to the front end of the development medium  105  begins to be manifested; the manifestation position is migrated according to the time elapse at over a critical temperature. At a predetermined delaying time, the color indication manifested at the indication window  103  is confirmed to check out the current state of a product to be stored. 
     According to another embodiment of the invention, as shown in  FIGS. 13 and 14 , a precise critical temperature indicator  100  is integrated into a single body and includes a temperature indication portion  220  on an upper portion thereof, a base portion  230  on a lower portion thereof and a separation sheet  224  projected therebetween. The temperature indication portion  220 , the upper portion of which is opaquely printed on parts except for an indication window  221  made of transparent synthetic resins, is previously molded in the form of a case receiving a development medium member  240  but made as a flat configuration all over. Herein, it is desirable to construct a portion except for the indication window  221  as an opaque printing portion. 
     The development medium member  240  includes a single supporting piece  241  made of an opaque sheet rather than a transparent one such as PE, PP, PET, PC, etc. in a predetermined size and a development medium  242  wound around the development medium  242  to meet both ends  245  and  246  thereof with each other. Herein, it is noted that both ends  245  and  246  can be unfolded in the opposite direction with each other being faced. The supporting piece  241  is constituted as an immediate member extended in a lengthwise or printed in a solid line on a center axis, which has an opaque color. The development medium  242  is made of a porous extended film or a silica extended film. 
     The development material member  250  is constituted as non-woven fiber  251  for absorbing a development material such as fatty acid, etc. 
     The base portion  230  is constituted as a lower portion made of a synthetic resin film such as transparent or opaque PE, PP, PET, PC, PVC, etc. 
     Therefore, the precise critical temperature indicator  100  includes the development material member  250  positioned on the center of the base portion  230  and the separation sheet  225  loaded on the development material member  250 . The temperature indication portion  220  is configured to contain the development medium member  240  in a receptacle  222  positioning the isolation sheet  225  between the development material member  250  and the development medium member  240 , in which the center of the development medium  240  is positioned directly under the indication window  221 . At that time, the separation sheet  225  is projected in parts from the receptacle  222  in the indication portion  220 . 
     On the other hand, the precise critical temperature indicator  100  is made welding the temperature indication portion  220 , the supporting piece  241  and the base portion  230  at once using a high heat or a high frequency, which are made of PE, PP, PC, etc. having a relative lower melting point. At that time, the isolation sheet  225  is made of PET having a relative higher melting point and not welded at the melting point of the temperature indication portion  220 , the supporting piece  241  and the base portion  230 . 
     Herein, the supporting piece  241  is printed to have a solid line  223  on the center portion thereof and made of an opaque synthetic resin member. The development medium  242  may be made cutting a sheet that is made of commercially porous extension films or silica coated porous extension films. The development material may be composed of a colorless transparent fatty acid or paraffin, silicon oil. 
     On the basis of such like a configuration, as the temperature sensor is operated with the removal of the isolation sheet  225 , the development material such as fatty acid oil impregnated into non-woven fiber is applied to both ends  245  and  246  of the development medium  242  at once, migrated to get the porous extension film to become transparent. Then the color tone of the supporting piece  241  directly below the indication window  221  on the upper of the indication portion  220  or the solid line  223  printed at the center is exposed to manifest the color thereof. 
     According to another embodiment of the invention, as shown in  FIGS. 16 , A and B, a manufacturing method of a precise critical temperature indicator  100  comprises a step of preparing an indication unit  260  including a plurality of indication portions  220  which made of a synthetic resin film and in the form of an upper case and a flat type. 
     The temperature sensing portion includes a plurality of development material members  250 , a plurality of development medium members  240  and an isolation sheet member  235  extended therebetween and mounted under the lower portion of the indication portion  220 . 
     More particularly, as shown  FIGS. 16 , C and D, a development medium unit  290  is prepared so that an immediate member  270  is constituted as a plurality of supporting pieces extended in a lengthwise, and a plurality of development medium member  240  made of a porous film meet both ends at numerous positions to be surrounded. 
     Then, a base unit  210  having an area formed as a plurality of base portions  230  is prepared to have a size identical or similar to one of the development medium unit  290  so that it is positioned on the lower of the development medium unit  290  including an indication unit  260 . 
     A plurality of development material members  250  is positioned on the base unit  210  corresponding to the development medium member  240  at their upper and lower portions. 
     A separation sheet member  235  made of a thin synthetic resin is positioned on the base unit  210  to package a plurality of development material  250  constituted as a plurality of development material units  200 , each of which cooperates with a plurality of development medium member  240  constituted as a development medium unit  290 . 
     Next, a sheet unit  280  is welded using a high temperature or a high frequency together with the indication unit  260  and the base unit  210  stuck to each other after loading the development medium unit  290  provided with the immediate member  270  on the base unit  210  that the development material unit  200  is covered with the separation sheet member  235 . 
     Also, as shown in  FIG. 17 , the precise critical temperature indicator  100  may be manufactured in larger quantities to have a configuration of a dual zipper. To it, first a coupling portion  261  having a groove is formed on both cross-sections of the indication unit  260 , and projectors  262  extended in a length to be fitted into the groove of the coupling portion  261  are formed on both sides of the base unit  210 . 
     On the indication unit  260  the development medium unit  290  (not shown) is positioned by the reference of a plurality of indication windows  221 , and on the base unit  210  there is positioned the development material unit  200 . 
     Thereafter, as the development material unit  200  including a plurality of the development material members  250  is arranged on the base unit  210 , and then the indication unit  260  is positioned on the development material unit  200 , so that they are assembly in a dual zipper configuration with both side ends being coupled to each other.