| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect basis weight on the basis of a ratio (P1/P0) between reception intensity (P0) when there is no recording material between ultrasonic transmission means and ultrasonic receiving means, and the reception intensity (P1) when there is a recording material between the ultrasonic transmission means and the ultrasonic receiving means, with high accuracy, without calculating the detection timing of a prescribed n-th wave transmitted from the ultrasonic transmission means. <P>SOLUTION: An ultrasonic detection device determines n of the n-th wave transmitted from the ultrasonic transmission means, using time lag of a receiving wave generated when ultrasonic waves are output with different frequencies. The receiving timing of the prescribed n-th wave to be used for calculating transmissivity can be detected irrespective of the presence of the recording material, thereby detecting the basis weight of the recording material with high accuracy. <P>COPYRIGHT: (C)2013,JPO&INPIT |
