Electric field-induced patterns in liquid crystals have been observed and studied for about 50 years. During this time, a great variety of structures, detected under different conditions, have been described; theoretical descriptions were also developed parallel with the experiments and a huge number of papers have been published. The non-vanishing interest in the topic is due to several factors. First, most experimentalists working with new (or even well-known) liquid crystals apply sooner or later an electric field for different purposes and, as a response, often (maybe undesirably or unexpectedly) have to face with emergence of patterns. Second, understanding the complexity of the formation mechanism of regular patterns in a viscous, anisotropic fluid is an extremely challenging theoretical task. Third, specialists in display fabrication or in other applications are also interested in the results; either to make use of them or in order to avoid field-induced patterns. In this review, we attempt to provide a systematic overview of the large amount of published results, focusing on recent achievements, about the three main types of electric field-induced patterns: transient patterns during the Freedericksz transition, flexoelectric domains and electroconvection. As a result of different instability mechanisms, a variety of pattern morphologies may arise. We address the physical background of the mechanisms, specify the conditions under which they may become effective, discuss the characteristics of the patterns, and summarize the possibilities of morphological transitions induced by frequency, voltage or temperature variations. Special emphasis is given to certain topics, which recently have gained enhanced interest from experimental as well as theoretical point of view, like driving with ultra-low frequencies or non-sinusoidal (superposed) waveforms, and the dynamics of defects and embedded colloidal particles. Assisting newcomers to the field, we also mention some, yet unresolved, problems, which may need further experimental and/or theoretical studies.

液晶中的电场感应图案已经被观察和研究了大约50年。在这段时间内，已经描述了在不同条件下检测到的各种各样的结构。在进行实验的同时还开发了理论说明，并发表了大量论文。对该主题的兴趣没有消失是由于几个因素。首先，大多数使用新的（或什至是众所周知的）液晶的实验者迟早会为不同的目的施加电场，并且作为响应，通常（可能不希望地或意外地）必须面对图案的出现。其次，了解粘性各向异性流体中规则图案形成机理的复杂性是一项极富挑战性的理论任务。第三，显示器制造或其他应用领域的专家也对结果感兴趣；要么利用它们，要么避免场致模式。在这篇综述中，我们试图以大量最新成果为重点，对电场感应模式的三种主要类型进行系统的概述：Freedericksz跃迁期间的瞬态模式，柔电畴和电对流。由于不稳定性机制的不同，可能会出现各种图案形态。我们介绍了这些机制的物理背景，指定了它们可能有效的条件，讨论了模式的特征，并总结了由频率，电压或温度变化引起的形态学转变的可能性。特别强调某些主题，这些主题最近在实验和理论上都引起了越来越多的兴趣，例如以超低频或非正弦（叠加）波形进行驱动，以及缺陷和嵌入的胶体粒子的动力学。为了协助新手进入该领域，我们还提到了一些尚未解决的问题，可能需要进一步的实验和/或理论研究。