Ink-based digital printing systems useful for ink printing include a photoreceptor layer configured to receive a layer of liquid immersion fluid. The liquid immersion fluid includes dampening fluid, dispersed gas particles, and charge directors that impart charge to the solid particles. The photoreceptor surface is charged to a uniform potential, and selectively discharged using an ROS according to image data to form an electrostatic latent image. The charged liquid immersion fluid adheres to portions of the photoreceptor surface according to the electrostatic latent image to form a fountain solution image. The fluid portion of the fountain solution image can be partially transferred to an imaging member and/or transfer member to form a dampening fluid image, either or both of which may be electrically biased. The dampening fluid image is inked on the transfer member, and the resulting ink image transferred to a print substrate.

A method for producing color steel plate with multicolored patterns, the PLC control module of servo control system collects the process and rotation speed of each roller of the roller coating unit, calculates out and makes the theoretical roller surface linear velocity be consistent with the process rotation speed; conversely, the actual roller surface linear velocity of each roller of roller coating unit is collected by servo control module having an encoder, and the signal of actual roller surface linear velocity is input into the PLC control system, so that PLC control system can compare actual and theoretical roller surface linear velocity, and adjust current frequency until actual and theoretical roller surface linear velocity are consistent. Control method ensures actual roller surface linear velocity is consistent with process rotation speed, so there is no need to stop the line for adjusting in the production process, thus increasing the production efficiency.