液晶显示器原理

wiki百科上的https://en.wikipedia.org/wiki/Liquid_crystal， Applications of liquid crystals一节，很多英文看不懂，只能知道成像的个大概的意思。利用偏光片（高中物理讲光有波的性质）液晶在电场下的变化，不通电的时候能让光波混乱，这样可以通过下一个偏光片。如果通电的时候，液晶发生变化就通不过了。

胡乱翻译的如下：

Liquid crystals find wide use in liquid crystal displays, which rely on the optical properties of certain liquid crystalline substances in the presence or absence of an electric field.
液晶在液晶显示器里广泛运用，依赖的就是液晶certain liquid crystalline在有电场和没有电场下的特性。

In a typical device, a liquid crystal layer (typically 4 μm thick) sits between two polarizers that are crossed (oriented at 90° to one another).
一般的液晶显示器上，液晶层有4微米的厚度，夹在两个方向互相垂直的偏光片之间。

The liquid crystal alignment is chosen so that its relaxed phase is a twisted one (see Twisted nematic field effect).[8]
液晶的在常态（relaxed）的时候是呈扭曲状态。（……）

This twisted phase reorients light that has passed through the first polarizer, allowing its transmission through the second polarizer (and reflected back to the observer if a reflector is provided).
这个时候扭曲的状态改变（reorient）了通过第一个偏光片的光线，使它能够正确通过第二层偏光片（然后，如果有反光设备就可以反射给观察者）。

The device thus appears transparent. When an electric field is applied to the LC layer, the long molecular axes tend to align parallel to the electric field thus gradually untwisting in the center of the liquid crystal layer.
因此设备是透明的。当一个电场加在液晶层的时候，分子的长轴趋向平行于电场方向排列，所以液晶不会在液晶层发生扭曲。

In this state, the LC molecules do not reorient light, so the light polarized at the first polarizer is absorbed at the second polarizer, and the device loses transparency with increasing voltage.
在这种情况下，液晶分子不会改变（reorient）光线，通过第一层偏光片的的光线通不过第二层偏光片，在加上电压后就失去了透光性了。

In this way, the electric field can be used to make a pixel switch between transparent or opaque on command.
用这种方式，电场就可以用命令来让一个像素在透明和不透明之前切换。

Color LCD systems use the same technique, with color filters used to generate red, green, and blue pixels.[8]
彩色LCD系统使用了相同的技术，使用颜色的滤片用来生成红、绿、蓝的像素。

Chiral smectic liquid crystals are used in ferroelectric LCDs which are fast-switching binary light modulators. Similar principles can be used to make other liquid crystal based optical devices.[51]
手性近液晶被用在铁电液晶，铁电液晶是快速切换binary（两种？）光调节器。类似的原理可以用在其他的一些根据液晶光学特性的设备上。

Liquid crystal tunable filters are used as electrooptical devices, e.g., in hyperspectral imaging.
液晶的可调节滤片可以用在电子设备上，比如，在超广谱成像上。