Printing apparatus and printing system

A printing apparatus comprising:

• a drive signal generating circuit that can generate a plurality of drive signals,
• an element to which said plurality of drive signals can be applied and that performs operation for ejecting ink according to the applied drive signals,
• a prevention circuit for preventing said plurality of drive signals from being simultaneously applied to said element,
• a plurality of switches that are provided in one-to-one correspondence with said plurality of drive signals, each of said switch controlling application of the corresponding drive signal to said element, and
• a switch controller that outputs, to said prevention circuit, a switch control signal for controlling actuation of said plurality of switches;
• wherein said element is a piezo element;
• wherein said prevention circuit is constituted by a logic circuit, and outputs, based on said switch control signal inputted thereto, a switch actuating signal for actuating said switches to each of said plurality of switches;
• wherein when said switch control signal inputted to said prevention circuit is for simultaneously applying said plurality of drive signals to said element, said prevention circuit outputs, to each of said plurality of switches, the switch actuating signal for actuating said switches so that a selected one of said drive signals is applied to said element;
• wherein when a forced application signal for applying said drive signals to said element regardless of said switch control signal is inputted to said prevention circuit, said prevention circuit outputs the switch actuating signal for actuating said switches so that a selected one of said drive signals is applied to said element;
• wherein when said switch control signal indicates, at the timing when said forced application signal is inputted to said prevention circuit, that one of said drive signals is to be applied to said element, said prevention circuit outputs the switch actuating signal for actuating said switches so that the drive signal indicated by that switch control signal is applied to said element;
• wherein when said switch control signal indicates, at the timing when said forced application signal is inputted to said prevention circuit, that a plurality of said drive signals are to be applied to said element, said prevention circuit outputs the switch actuating signal for actuating said switches so that a particular one of said drive signals is applied to said element;
• wherein said switch controller outputs said switch control signal based on gradation data indicating a gradation level of a dot to be formed by the ejected ink;
• wherein said switch controller outputs said switch control signal for each of said plurality of drive signals;
• and
• wherein said switch controller outputs
• at least two said switch control signals asynchronously with each other, or
• all of the plurality of said switch control signals synchronously.

A printing system comprising:

• a printing apparatus that includes
• a drive signal generating circuit that can generate a plurality of drive signals,
• an element to which said plurality of drive signals can be applied and that performs operation for ejecting ink according to the applied drive signals, and
• a prevention circuit for preventing said plurality of drive signals from being simultaneously applied to said element;
• and
• a print control apparatus that controls operations of said printing apparatus.