Image forming apparatus, droplet discharge control method, and storage medium

An image forming apparatus, comprising:

• piezoelectric elements each with a common electrode on one side and an individual electrode on another side;
• nozzles configured to discharge droplets;
• and
• circuitry configured to determine driven piezoelectric elements to be driven among the piezoelectric elements at a print timing based on image information to be printed, select a drive signal from a plurality of drive signals per driven piezoelectric element at the print timing, and simultaneously supply the selected drive signal to individual ones of the driven piezoelectric elements via the individual electrode to discharge the droplets through the nozzles to form an image,
• the drive signals each comprise a different pulse waveform having a main pulse that rises in a slope shape during a rising time and finishes rising at an end time,
• the circuitry further configured to:
• generate the plurality of drive signals so that end times of a group of drive signals other than a reference drive signal that drives a largest number of the driven piezoelectric elements among the plurality of drive signals fall within a range defined as being within a threshold amount of time of an end of the rising time of the main pulse of the reference drive signal, and the end times are staggered across the range;
• and
• select the selected drive signal from the plurality of drive signals per driven piezoelectric element at the print timing based on the image information.

A non-transitory storage medium storing computer-readable program code for causing an image forming apparatus including piezoelectric elements each with a common electrode on one side and an individual electrode on another side and nozzles configured to discharge droplets, to execute a droplet discharge control method:

• the method comprising:
• determining driven piezoelectric elements to be driven among the piezoelectric elements at a print timing based on image information to be printed;
• selecting a drive signal from a plurality of drive signals per driven piezoelectric element at the print timing;
• and
• simultaneously supplying the selected drive signal to individual ones of the driven piezoelectric elements via the individual electrode to discharge the droplets through the nozzles to form an image,
• wherein the drive signals each comprise a different pulse waveform having a main pulse that rises in a slope shape during a rising time and finishes rising at an end time;
• wherein the method further comprises generating the plurality of drive signals so that end times of a group of less influential drive signals other than a most influential drive signal among the plurality of drive signals fall within a range defined as being within a threshold amount of time of an end of the rising time of the main pulse of the most influential drive signal, and the end times are staggered across the range;
• wherein selecting the selected drive signal comprises selecting the selected drive signal from the plurality of drive signals per driven piezoelectric element at the print timing based on the image information.