Image forming apparatus and position detection method

An image forming apparatus, which is configured to form an image on a sheet, comprising:

• a plurality of image forming units configured to form a plurality of images, each having a different color;
• a sensor configured to measure reflected light from a color pattern formed on a transfer member, the color pattern being used for detection of a color misregistration amount;
• a first comparator configured to compare a measurement value of the sensor with a first threshold value;
• a second comparator configured to compare the measurement value of the sensor with a second threshold value being different from the first threshold value;
• and
• a controller configured to control the plurality of image forming units to form, on the transfer member, a plurality of color patterns, each having a different color, control the sensor to measure reflected light from the plurality of color patterns, cause the first comparator to compare measurement values of reflected light from the plurality of color patterns with the first threshold value to acquire first data, cause the second comparator to compare the measurement values of reflected light from the plurality of color patterns with the second threshold value to acquire second data, detect the color misregistration amount related to relative position of a color pattern having a reference color among the plurality of color patterns and a color pattern having another color among plurality of color patterns based on the first data and the second data, and determine an image forming condition for adjusting an image forming position of an image having other color different from the reference color based on the color misregistration amount,
• wherein the controller generates correction data based on the first data and the second data, and detects the color misregistration amounts based on the second data and the correction data,
• wherein the first data corresponds to a binary digital signal,
• wherein the second data corresponds to a binary digital signal,
• wherein the controller determines third data corresponding to an exclusive OR of the first data and the second data, and generates the correction data based on the third data, and
• wherein the third data corresponds to a binary digital signal.