Marking determining method and marking determining apparatus

A proper marking determining apparatus for determining whether marking on a material to be printed is proper or not, the marking being formed by a marking apparatus which includes:

• a carrying section for carrying the material to be printed;
• a laser oscillating section capable of forming a dot by irradiating the material to be printed which is carried by the carrying section with a laser beam at a predetermined position;
• a laser control section for controlling the laser oscillating section to form a marking pattern by arranging dots in a predetermined position in the material to be printed, the proper marking determining apparatus comprising:
• An infrared sensor provided so as to be able to detect a plurality of finished dots, which are formed on the material to be printed by irradiation with laser beams, on the downstream side in the feed direction of the material to be printed with respect to an irradiation position of the laser beam on the material to be printed, which position is irradiated with the laser beam oscillated by the laser oscillating section;
• and
• A determining section for determining whether marking on the material to be printed is proper or not by comparing an output of the infrared sensor, which includes an amount of an infrared ray emitted from the finished plurality of dots and the amount of infrared rays emitted from the material being melted by the irradiation of the laser beam, with a preset threshold.