The Simulation, Optimization And Test Of Piezoelectric Inkjet Printhead

With the prosperous development of inkjet printing industry and widely application in other industry for piezo drop-on-demand inkjet, the demand of piezoelectric printhead becomes higher and higher. Now, there wasn’t a piezoelectric printhead with independent intellectual property rights in domestic market. In this paper, a design optimization for the structure parameters and voltage waveform of self-developed piezoelectric printhead was discussed.(1)The size of piezoelectric printhead was optimized by using computer numerical simulation software COMSOL for obtaining fine inkjet performance. The simulation results for the thickness of SiO2 and PZT and the width of PZT show, there is a optimum size making the best jet performance of printhead. The width simulation and test results show, the amplitude of vibrating plate increase with increasing width of vibrating plate. And the amplitude of vibrating plate decreased after an initial increase with increasing width of PZT. In order to obtain a higher displacement under low voltage, a double-layer PZT structure was simulated. The simulation results show the displacement of double-layer PZT structure is twice the displacement of single PZT structure under the same condition. The thickness of nozzle layer was also simulated. A suitable thickness was confirmed to balance the inkjet performance and structural strength of nozzle layer.(2)A driving voltage waveform design method based on pressure wave superposition was proposed. The parameters of designed double-trapezoidal on-load voltage waveform by this method are 4μs(t1),14μs (t2), 1μs (t3),33μs (t4)and 4μs(t5). In order to achieve high frequency inkjet, a voltage waveform based on negative feedback was design. The simulation results show, the residual oscillation of vibrating plate get down rapidly when loading this voltage waveform for piezoelectric printhead.(3)In order to evaluate the performance of piezoelectric printhead in the manufacturing process, the laser droppler displacement test of piezo vibrating plate and printhead are taked. The test results about various voltage show, the displacement of piezo vibrating plate grow with the amplitude of voltage, and grow slowly when the amplitude of voltage more than 60V. More over, the fatigue life of printhead is only 10 minute when the on-load voltage is 60V. So the load voltage should be less than 60V. The test results about various load voltage waveform(sine wave, triangular wave, trapezoidal wave, square wave) show, there are excellent performance on ink suction and ink compression for double trapezoidal on-load voltage waveform.(4)Finally, the drop injection of completed piezoelectric printhead show the effectiveness of the structure and on-load voltage waveform of the piezoelectric printhead.