| 摘要 |
PURPOSE: To facilitate the manufacture, and to improve reliability so as to stabilize quality by overlapping porous sheets having a display surface coated with display ink, which reacts with steam, between high molecular material layers, which do not transmit steam and air, at parts except for a measuring part so as to cut the air of the periphery. CONSTITUTION: Display ink 14, which is discolored by the existence of steam, is used, and a mount 12 is formed of a porous material sheet, which is obtained by forming the fiber material into the net material. Layers 20, 22 of impermeable resin film are overlapped with an upper and a lower surfaces and a peripheral part of four edges of the sheet 12, and a range 32 is left as it is not overlapped, and a measuring hole 36 is punched at a position close to an edge 37. This tool 10 is arranged inside a chamber, and when a steam processing is performed in the vacuum condition, the air near an edge 39 is discharged last, and the residual air prevents the contact of the steam with the display ink 14, and length of a discoloring part of the sheet 12 is changed in response to the quantity of the residual air. |
