Printing apparatus and method of controlling printhead

A method for controlling a printhead, the method comprising:

• providing the printhead including a plurality of printing elements and driving circuits which have at least one source follower transistor and correspond to each of the plurality of printing elements;
• in a case where a number of printing elements driven simultaneously does not exceed a predetermined number, perform a first control for driving the at least one source follower transistor by a fixed pulse width irrespective of the number of printing elements driven simultaneously, and
• in a case where the number of printing elements driven simultaneously does exceed the predetermined number, perform a second control for changing a pulse width to drive the at least one source follower transistor based on the number of printing elements driven simultaneously,
• wherein the predetermined number is determined such that the driving circuits keep a voltage across the printing elements fixed.