| 摘要 |
PROBLEM TO BE SOLVED: To prevent reduction in accuracy of correcting environmental change which is caused by displacement of a basis-weight detection sensor, to improve the accuracy of determining basis weight of a recording medium.SOLUTION: A recording medium determination apparatus includes: a transmission section 31 for transmitting ultrasonic waves; a receiving section 32 which outputs a signal corresponding to the ultrasonic waves transmitted and received from the transmission section 31; a peak extraction section 344 which detects a value of the signal output from the receiving section 32; a control section 60 which determines basis weight of a recording medium on the basis of the value of the signal detected by the peak extraction section 344; and a timer 345 which measures the time from when the transmission section 31 transmits the ultrasonic waves to when the peak extraction section 344 performs detection. The control section 60 calculates change in distance between the transmission section 31 and the receiving section 32 at the time of factory shipment, on the basis of the time measured by the timer 345 at the time of factory shipment and the time measured by the timer 345 after the factory shipment (S104), and determines basis weight of the recording medium, according to the calculated change in distance and the detected value of the signal (S106-S110). |
