| 摘要 |
PROBLEM TO BE SOLVED: To obtain a top plate facilitating the removal of dirt such as scorched food even when it sticks and capable of maintaining the effect over a long period of time by imparting a fluorine-contg. surface structure and a specified surface roughness to a cooking face. SOLUTION: This top plate has a cooking face on which a body to be heated is put and the substrate is made of crystallized glass. The cooking face has a fluorine-contg. surface structure and 0.5-25μm surface roughness Ry stipulated by JIS-B0601-94. The crystallized glass, e.g. contains a solid soln. ofβ-quartz deposited as principal crystals and has -10 to 10×10<-7> / deg.C coefft. of thermal expansion in the temp. range of 30-750 deg.C and >=30% average light transmissivity at 360-600nm in the case of 3mm thickness. When the coefft. of thermal expansion is not within the range, thermal breakage is liable to be caused by repetitive use. In the case of <10% average light transmissivity, a heating element or other contents are not seen and fine appearance is deteriorated.
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