Data processing device and image forming apparatus for identifying position of recording medium

An image forming apparatus comprising:

• a light emission portion configured to emit linear light toward a recording medium that is being conveyed;
• a plurality of light reception portions configured to output a plurality of pieces of first data that have different levels depending on amounts of light incident on the plurality of light reception portions upon reception of the linear light;
• a binarization portion configured to generate binarization data by performing a binarization process on the plurality of pieces of first data using a predetermined threshold;
• a position identifying portion configured to identify a position of the recording medium based on the binarization data;
• an image forming portion configured to form an image on the recording medium based on the position;
• a first light emission control portion configured to cause the light emission portion to emit specific linear light having a specific amount of light at a timing when no recording medium is conveyed;
• a data acquiring portion configured to acquire a plurality of pieces of second data from the plurality of light reception portions, the plurality of pieces of second data having different levels depending on amounts of light incident on the plurality of light reception portions upon reception of the specific linear light;
• a level acquiring portion configured to acquire a maximum level and a minimum level from among the levels of the plurality of pieces of second data;
• a characteristic data storage portion preliminarily storing characteristic data that indicates levels of the plurality of pieces of second data in association with an amount of linear light emitted from the light emission portion toward the recording medium when no foreign substance is adhered to the light emission portion or the plurality of light reception portions;
• a light amount deriving portion configured to derive a set light amount of the linear light based on the threshold, the maximum level, the minimum level, and the characteristic data;
• and
• a second light emission control portion configured to cause the light emission portion to emit linear light having the set light amount, wherein
• the characteristic data is a reduction ratio of the plurality of pieces of second data output from the plurality of light reception portions with respect to the recording medium, and
• the light amount deriving portion derives the set light amount that satisfies following formulas (1) and (2):
• C2≤T1 (1)
• (C2×B1)/(B2×K)>T1 (2),
• wherein in the formulas (1) and (2), T1 denotes the threshold, B1 denotes the minimum level, B2 denotes the maximum level, K denotes the reduction ratio, and C2 denotes a level corresponding to the set light amount.