ABSTRACT
Liquid crystal displays (LCDs) and photonic devices play a pivotal role to augmented reality (AR) and virtual reality (VR). The recently emerging high-dynamic-range (HDR) mini-LED backlit LCDs significantly boost the image quality and brightness and reduce the power consumption for VR displays. Such a light engine is particularly attractive for compensating the optical loss of pancake structure to achieve compact and lightweight VR headsets. On the other hand, high-resolution-density, and high-brightness liquid-crystal-on-silicon (LCoS) is a promising image source for the see-through AR displays, especially under high ambient lighting conditions. Meanwhile, the high-speed LCoS spatial light modulators open a new door for holographic displays and focal surface displays. Finally, the ultrathin planar diffractive LC optical elements, such as geometric phase LC grating and lens, have found useful applications in AR and VR for enhancing resolution, widening field-of-view, suppressing chromatic aberrations, creating multiplanes to overcome the vergence-accommodation conflict, and dynamic pupil steering to achieve gaze-matched Maxwellian displays, just to name a few. The operation principles, potential applications, and future challenges of these advanced LC devices will be discussed.
ABSTRACT
INTRODUCTION: The mode clamping mechanism is the most important part of forming section for the plastic injection molding machine. If this mechanism has double-toggle effects at the close position, it will get a larger clamping force and have higher safety. This study focuses on the optimal design of the Watt-chain mechanism with double-toggle effects at the close position. METHODS: The Watt-chain double-toggle mechanism is chosen to be the mold clamping mechanism by referring to the existing patents. Then, the kinematic characteristics of the Watt-chain double-toggle mechanism are analyzed by the vector loop method. Finally, based on the kinematic requirements and the proposed optimal design process according to the objective function, the optimal design on Watt-chain double-toggle mechanism is accomplished in this study. RESULTS: This study proposes an optimal design process on Watt-chain double-toggle mold clamping mechanism. By following the optimal design process, the optimal Watt-chain double-toggle mold clamping mechanism has a maximum acceleration 3418â mm/s2 (amax = 3418â mm/s2) and a force ratio is 2.24 (Fin/Fout = 2.24). DISCUSSION: According to the studies on the optimal designs of mechanisms, the optimal Watt-chain double-toggle mechanism, which is better than the multiple-joint double-toggle mold clamping mechanism in the existing patent by reducing 19.5% of acceleration and 30% of a driving force, is proposed. The results of this study could be the design reference in engineering when designing mold clamping mechanisms for plastic injection molding machines.
Subject(s)
Plastics , Biomechanical Phenomena , Constriction , InjectionsABSTRACT
Hydrogel ionotronics are intriguing soft materials that have been applied in wearable electronics and artificial muscles. These applications often require the hydrogels to be tough, transparent, and 3D printable. Renewable materials like cellulose nanocrystals (CNCs) with tunable surface chemistry provide a means to prepare tough nanocomposite hydrogels. Here, we designed ink for 3D printable sensors with cationic cellulose nanocrystals (CCNCs) and zwitterionic hydrogels. CCNCs were first dispersed in an aqueous solution of monomers to prepare the ink with a reversible physical network. Subsequent photopolymerization and the introduction of Al3+ ion led to strong hydrogels with multiple physical cross-links. When compared to the hydrogels using conventional CNCs, CCNCs formed a stronger physical network in water that greatly reduced the concentration of nanocrystals needed for reinforcing and 3D printing. In addition, the low concentration of nanofillers enhanced the transparency of the hydrogels for wearable electronics. We then assembled the CCNC-reinforced nanocomposite hydrogels with stretchable dielectrics into capacitive sensors for the monitoring of various human activities. 3D printing further enabled a facile design of tactile sensors with enhanced sensitivity. By harnessing the surface chemistry of the nanocrystals, our nanocomposite hydrogels simultaneously achieved good mechanical strength, high transparency, and 3D printability.
