| 摘要 |
PROBLEM TO BE SOLVED: To provide an ink jet printer that can discriminate types of a printing paper sheet accurately without slowing down a printing speed. SOLUTION: There are provided a light emitting diode 11a emitting predetermined light and a phototransistor 11b receiving reflected light from the emitted light from a print sheet S and outputting photocurrent corresponding to the intensity of the reflected light on a paper feed portion 15. Light emission by the diode 11a for the print sheet S and light reception of the reflected light for the phototransistor 11b are performed three times in total, which are right before start of conveyance of the sheet S, at supply adjustment, and at positioning to a print start position. The discrimination means 12 discriminates the type of the sheet S based on an average value B of a voltage value of the photocurrent output from the phototransistor 11b and a standard voltage value R that has been preset, and makes the type of the sheet effective to a printer driver 21. COPYRIGHT: (C)2004,JPO
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