| 摘要 |
PROBLEM TO BE SOLVED: To provide a sheet tray and an image forming device capable of detecting residual quantity of paper without using a connector or a harness. SOLUTION: A pressure sensor 200 is provided on a side surface part 314 of a paper tray 31a (31b and 31c), and an electric wave is generated from a transmission part 111 to the pressure sensor 200. The electric wave transmitted from the transmission part 111 is received instead of an electric signal by the pressure sensor 200 to be converted into a surface acoustic wave. For this surface acoustic wave, amplitude, phase difference, frequency, etc., are varied in accordance with variance of pressure added to the pressure sensor 200. The variation of the surface acoustic wave is received as an electric signal by a receiving part 112, and a control part 70 analyzes the variation of the electric signal. The control part 70 detects residual quantity of paper in the paper tray 31a based on information by analysis. COPYRIGHT: (C)2007,JPO&INPIT
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