摘要 |
A fuel tank is allowed to hold any of types of liquid fuels and currently hold one type of liquid fuel. A light emitting element outputs a light beam of a predetermined emission spectrum to the liquid fuel of the fuel tank. The liquid fuel changes the light beam to a reflected light beam of a reflection spectrum according to spectral characteristics of the liquid fuel. The reflection spectrum is peculiar to the type of the liquid fuel of the fuel tank. A light receiving element detects the reflection spectrum, and a control circuit receives the detected reflection spectrum from the light receiving element. The control circuit collates the detected reflection spectrum with a referential reflection spectrum corresponding to each fuel type and identified the type of the liquid fuel of the fuel tank according to a collation result.
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