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(11) | EP 1 643 540 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Lamp type heater and manufacturing method thereof |
| (57) A luminescent color is controlled easily without changing a manufacturing condition
and a film material, by forming films on a radiation transmissive bulb on whose surface
a Frost process is performed while varying a film thickness into concave and convex
to thereby adjust the film thickness. A depth of a Frost 19 formed by performing a
Frost process on a surface of a bulb 12 made of quartz glass, is set to be approximately
over 4 µm, or 2µm or more and 4µm or less. As a first layer, a low refractive index
film 21 whose major constituent is SiO2 is formed by coating it on the Frost 19 by a dipping method and thereafter baking
it, and as a second layer, a high refractive index film 22 whose major constituent
is Fe2O3 is formed by coating it by the dipping method and thereafter baking it. The low refractive
index films 21 and the high refractive index films 22 of a third and subsequent layers
are alternately formed in plural layers.
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