Performance improvement of professional printing systems : from theory to practice

Performance Improvement of Professional Printing Systems: from theory to practice Markets demand continuously for higher quality, higher speed, and more energy-efficient professional printers. In this thesis, control strategies have been developed to improve the performance of both professional inkjet and laser printers. Drop-on-Demand (DoD) inkjet printing is considered as one of the most promising printing technologies. It offers several advantages including high speed, quiet operation, and compatibility with a variety of printing media. Nowadays, it has been used as low-cost and efficient manufacturing technology in a wide variety of markets. Although the performance requirements, which are imposed by the current applications, are tight, the future performance requirements are expected to be even more challenging. Several requirements are related to the jetted drop properties, namely, drop velocity, drop volume, drop velocity consistency, productivity, and reliability. Meeting the performance requirements is restricted by several operational issues that are associated with the design and operation of inkjet printheads. Major issues that are usually encountered are residual vibrations in and crosstalk among ink channels. This results in a poor printing quality for high-speed printing. Given any arbitrary bitmap, the main objective is to design actuation pulses such that variations in the velocity and volume of the jetted drops are minimized. Several model-based feedfoward control techniques using an existing model are implemented to generate appropriate input pulses for the printhead. Although the implementation of the model-based techniques shows a considerable improvement of the printhead performance compared with the current performance, further improvements are still necessary. We observe that besides the pulse shape the state of the ink surface at the nozzle plate (speed, position) at the start of the pulse influences the drop velocity considerably. This state at firing depends also on previous pixels in the bitmap of the image. Consequently, any pulse design has to guarantee almost the same initial state when firing a drop. Based on these facts, a model-free optimization scheme is developed to minimize the drop velocity variations taking into account the bitmap information. Experimental results show the effectiveness of the optimized pulses. Laser printing systems are highly depending on the appropriate combination of several design factors so as to become functional in a desired working range. The physical printing process involves multiple temperature set points at different places, precise electro-magnetic conditions, transfer of toner through certain pressures and layouts, and many other technical considerations. In the laser printing system there are several challenging issues and unknown disturbances. They originate from different sources, such as the printer itself (unknown phenomena appear, disturbances that are not foreseen, wear, contamination, failures, bugs), the environment of the system (power supply variations, temperature, humidity, vibrations), and the printing media (weight, coating, thermal properties, humidity characteristics, and initial temperature). These issues have a negative effect on the stability and performance of the laser printing system. The objective is to design a control scheme to achieve printing quality requirements and a high productivity. Good printing quality means that the fusing temperature should track a certain reference signal at different operating conditions. Based on the printing system behavior, we propose two different control schemes to cope with the large parameter variations and disturbances, namely, a Model Reference Adaptive Controller (MRAC) and a nonlinear (scheduled) observer-based output feedback control scheme. Both control techniques yield considerable performance improvements compared with the present industrial controller

Improved convergence of MRAC design for printing system

This paper deals with the improved design of stable model reference adaptive systems, by introducing a nonlinear adaptation gain. Uniform asymptotic stability of the system is demonstrated for both state and output feedback cases. A simulation example shows the effectiveness of the proposed approach when large parameter variations and disturbances are active. It is also being applied to control a real printing system

Model-free optimization based feedforward control for an inkjet printhead

Inkjet is an important technology in document printing and many new industrial applications. As inkjet developments are moving towards higher productivity and quality, it is required to achieve small droplet size which is fired at a high jetting frequency. Inkjet printers are now widely used to form conductive traces for circuits, as well as color filters in LCD and plasma displays, what makes the printing quality an important issue. In this paper, an optimization-based feedforward control is proposed to improve the printing quality of the piezoelectric inkjet printer. A novel optimized input pulse is proposed and a model-free optimization is applied to obtain the optimal parameters of the proposed pulse. The proposed optimal pulse is applied to the inkjet printhead and the system performance is investigated

Improved convergence of MRAC design for printing system

This paper deals with the improved design of stable model reference adaptive systems, by introducing a nonlinear adaptation gain. Uniform asymptotic stability of the system is demonstrated for both state and output feedback cases. A simulation example shows the effectiveness of the proposed approach when large parameter variations and disturbances are active. It is also being applied to control a real printing system

Improving the printing quality of an inkjet printhead using MIMO model predictive control

Drop-on-Demand inkjet printing is considered one of the most promising printing technologies that offers several advantages including high speed, quiet operation and compatibility with a variety of substrates. That makes it an important manufacturing technology serving a wide variety of markets. Though the performance criteria imposed by today's applications are quite tight already, the future performance requirements will be even more challenging. However, the attainable performance is limited by two operational issues that are generally encountered, namely residual vibrations and cross-talk. This paper presents an approach based on a MIMO Model Predictive Control (MPC) with which the input waveform is designed to improve the printing quality of a piezoelectric inkjet printer. The narrow-gap model is employed to predict the response of the ink channel under the application of the piezo input. Simulation and experimental results are presented to investigate the performance of the proposed approach

Model-free feedforward control of inkjet printhead

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Experimental-based feedforward control for a DoD inkjet printhead

Markets demand continuously for higher quality, higher speed, and more energy-efficient professional printers. Drop-on-Demand (DoD) inkjet printing is considered as one of the most promising printing technologies. It offers many advantages including high speed, quiet operation, and compatibility with a variety of printing media. Nowadays, it has been used as low-cost and efficient manufacturing technology in a wide variety of markets. Although the performance requirements, which are imposed by the current applications, are tight, the future performance requirements are expected to be even more challenging. These print requirements are related to the jetted drop properties, namely, drop velocity, drop volume, drop velocity consistency, productivity, and reliability. Meeting these performance requirements is restricted by several operational issues that are associated with the design and the operation of inkjet printheads. Major issues that are usually encountered are residual vibrations and crosstalk among ink channels. These result in a poor printing quality for high-speed printing. The main objective is to design a feedforward control strategy such that variations in the velocity and volume of the jetted drops are minimized. In this article, an experimental-based feedforward control scheme is proposed to improve the performance of a professional inkjet printer

Modeling and control of inkjet printhead

Abstract onl

Présentation : Montréal-jazz

A reference model tracking control technique for nonlinear systems based on the Takagi-Sugeno model is proposed. The control design synthesis is aimed to reduce the tracking error for all bounded reference inputs and disturbances and to guarantee L2 gain performance. A nonlinear static output feedback controller is proposed to tackle this problem. Unlike the approaches using a single quadratic Lyapunov function, a parameter varying quadratic Lyapunov function is employed in our approach. The controller synthesis is formulated in terms of a feasibility problem of a set of linear matrix inequalities, which can be efficiently solved. A simulation example of a two-link robot system demonstrates the tracking performance and the validity of the proposed approac

Robust L2 control for a class of nonlinear systems: a parameter varying lyapunov function approach

The problem of robustly stabilizing a class of nonlinear systems by using an L2 state feedback based controller is proposed. A class of nonlinear systems is approximated by a Takagi-Sugeno (T-S) model. A robust stabilization technique is proposed to override the effect of approximation error between the original nonlinear system and the approximated T-S model. A sufficient condition is derived to ensure the robust stability of the L2 state feedback based controller with guaranteed disturbance attenuation level. Unlike the approaches using a single quadratic Lyapunov function, a parameter varying quadratic Lyapunov function is employed in our approach. A transformation is presented to formulate the problem in terms of a linear matrix inequality problem for which efficient optimization techniques are available. A simulation example of an inverted pendulum on a cart illustrates the performance and the validity of the proposed approach