| 摘要 |
<p>PURPOSE:To set a certain level of reference voltage for each element to discriminate the presence or absence of a mark, by maximizing the level difference between the presence and absence of the mark with a simple circuit constitution in which a controlling resistance in series to a CdS. CONSTITUTION:A CdS, i.e., a photoconductive element is used as a sensor 14, and a controlling resistance is connected in series to the CdS to correspond to a code mark. These CdSs and resistances are arrayed in a matrix in correspondence to the code marks. With such controlling resistances, the difference of voltage levels between the presence and absence of the code mark is maximized regardless of the variance of the resistance value of each CdS. Thus the reference voltage is set constant for a comparator 16 that discriminates the presence or absence of the code mark. This reference voltage is obtained by a reference voltage sensor 15.</p> |
