To form a higher-definition image by providing a device with a pair of barlike electrodes with which a conductive string is brought into contact, a means making the conductive string travel at a prescribed speed, a means impressing a fixed voltage between a pair of electrodes and a means measuring the current value of a pair of electrodes.
When a driving roller 38 is made to travel at a prescribed speed by a motor 40, the conductive string 18 is made to travel while being brought into contact with a pair of barlike electrodes 22 and 24. At this time, when the current value A (t) of a pair of electrodes 22 and 24 is continuously measured, the resistance value of one string 18 in the length direction can be continuously obtained from the value of the voltage E by using a required expression. By a personal computer 30, the resistance value per unit length is extracted from the inputted resistance value and the standard deviation of the string 18 is obtained by the required expression. Thus, since the resistance value per unit length and the standard deviation of the string 18 can be precisely obtained even when the string 18 is long, the resistance value of a brush type electrifier and the like can be judged in the stage of an original string.
KANO OSAMU
NISHISATO HISAHIRO
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