关于LCD设计的英文文献

英文原文

LCD Design Guide

The following sections provide basic information on LCD glass and LCD modules, which is useful when you start designing your own LCD or submit requests to LCD manufacturers.

Types of LCD Products - Glass or Modules

The most fundamental decision to make is whether the display will have the drive circuitry attached (module), or not (glass only). There are advantages and disadvantages to each approach.

When purchasing a Custom LCD Module, the basic electronic design work will be done by the manufacturer. This obviously saves design time and reduces the manpower needed to bring a product to market. You can benefit from the experience we have gained during our previous designs to shorten the design cycle and deliver an optimized product. The major decisions you need to make are the interface type, with standard serial or parallel interfaces being the most common, and the type of integrated backlighting desired. The temperature range, viewing angle, viewing mode, and contrast will need to be considered, but those decisions are common to both approaches.

A glass only design puts the design burden on the end user. You will need to learn a great deal about LCD's in order to complete your design. Luckily, our website provides Application Information and Web Links to assist you in the search for the information you may need.

The main reasons to buy just the LCD glass are to reduce costs, and provide design flexibility. The total cost of the components necessary to build the drive circuitry is typically less than the cost of a pre-built module, and as long as you have space on your existing PC board, you won't have to pay for an extra PC board on which to mount the display, and have access to cost effective assembly and test. By doing a little homework, your design will work just as well as a module, and will allow the flexibility most designers need to adapt their design to ever changing demands.

Types of LCD Images

The LCD can contain character icons, segments, graphic dot arrays, or any

combination.

Icons: By making a custom LCD, you can place images on the glass that specifically complement your produce, these are called "Icons". These silhouettes can take the shape of any image you may need and count as one pixel or dot on the LCD.

Segments: Segments on an LCD display make up a larger character, such as a segment in a seven segment numeric character (displays 0-9), or a segment in a 14 segment alpha-numeric character (displays 0-9 & A-Z).

Dot Arrays: These dot arrays can be made in almost any size and dot count. Examples would be character displays that use a series of 5x7 dot arrays to create a string of alphanumeric characters, or the larger 320 x 240 graphic arrays that make images along with variable size alpha-numeric characters.

Types of Liquid and Technology

The type of technology used is determined by the specific performance requirements you set for the display that you are designing. Since several variations will do a fine job, the ultimate consideration is cost. So here is a quick breakdown of the technologies we offer.

TN: Low production and NRE costs, poor viewing angle, average contrast. Coloration: Black on Gray. Static preferred, but operates well up to a 32:1 Multiplex rate. LCD Glass favorite.

STN: Medium production and NRE costs, average viewing angle, average contrast. Coloration Black on Green, or Dark Blue on Gray. Works well at high Multiplex rates. LCD Module favorite,high end LCD glass choice.

FSTN: Medium high production and NRE costs. Good viewing angle, excellent contrast. Coloration Black on White. Works well at high Multiplex rates. Higher end LCD Module favorite.

Negative Image: This is an effect that reverses the image on the display and is only offered with transmissive displays. The visual effect is to allow the backlight to define the pixels turned "on" (transparent), while the "off" pixels remain opaque. This configuration works best in moderate to low light conditions.

Viewing Mode and Polarizers

The viewing mode is controlled by the rear polarizer, and how much it does or does not reflect light. We offer three modes.

Reflective: This type of polarizer gives the display the brightest appearance in

high to moderate ambient light conditions, with the highest contrast ratio possible. Unfortunately, it will be difficult to read at night or under changing lightning conditions (think Game Boy).

Transflective: (Favorite solution) If your display must be readable under a wide range of lighting conditions, you will generally want a transflective display so that it will look very good in the bright sunlight, but will also be back-lightable at twilight and at night. The tradeoff with a transflective display is that it will not look as good as a reflective display during the day, and it will not look as good as a transmissive display at night. It will however enable you to have an acceptable compromise between the two, and provides a very acceptable appearance.

Transmissive: This display needs to have a working backlight, unless it gets its light from being a "window" type of device where the area behind the LCD has a light source room ambient light. Where it is in a contained display, the backlight may have a problem overpowering high ambient light. This type of display looks great for an indoor application, but is not very good in applications where power consumption is a problem and it needs a strong backlight. Remember, this choice of polarizer will not operate unless there is an active backlight.

The polarizers are also affected by temperature, and a quality grade must be specified when choosing a polarizer. After you have determined your environmental temperature requirements, you then need to choose the polarizer grade. Here are your typical choices.

Commercial Grade Polarizers: Displays which will be indoors, or mostly indoors, can use commercial grade polarizers. These polarizers will hold up very well when used in most instrumentation, office and home products, and other applications where the products will be protected from high temperature, sunlight, and humidity.

Industrial Grade Polarizers: For harsh environments, a polarizer specifically designed for outdoor, extremely humid conditions should be used. We call these polarizers industrial grade.

Viewing Direction

The viewing direction of a LCD part is defined as the angles above, below, left, and right of the point-of-view that is perpendicular to the center of the display.

6:00 viewing direction has optimum contrast from below the perpendicular viewing plane (most popular).

12:00 viewing direction has optimum contrast from above the perpendicular

viewing plane.

9:00 viewing direction has optimum contrast to the left side of the perpendicular viewing plane (uncommon).

3:00 viewing direction has optimum contrast to right side of the perpendicular viewing plane (uncommon).

Please keep in mind that viewing direction is less important for a direct drive display. As a general rule, the higher the multiplex rate, the more important the viewing direction becomes. Also, if your display is going to be viewed by a person wearing polarized sunglasses, you must specify this in the comment section to ensure that the display will not look blank to an observer wearing polarized sunglasses. However keep in mind that for quoting purposes, the price of the display will not change much (usually only a few cents) if you change your mind for the final viewing direction of the display.

Environmental Considerations - Temperature Range

The operating and storage temperature range of an LCD are important considerations, since operating outside of those ranges will result in a display that is not readable (outside operational range) or permanently damage the LCD (outside storage range). The combination of the LCD fluid, polarizers, operational voltage, and multiplex rate determine the temperature range of the part. So instead of going through the different combinations of these parameters, here are some general guidelines you can use when specifying the temperature range of your LCD, and manufacturer can then assist you in the process of selecting the correct fluid, polarizers, and voltage for your application. These values are typical operating temperature ranges.

LCD TN Glass / Static or Low Multiplex Rates: Standard Temp Range: -10??C to +60??C, Wide Temp Range: -40??C to +80??C, Specialized Temp range: down to -55??C, or up to +110??C

LCD TN Modules / Multiplexed: Standard Temp Range: -0??C to +50??C, Wide Temp Range: -20??C to +70??C, Specialized Temp range: -40??C to +90??C LCD STN & FSTN Modules / Multiplexed: Standard Temp Range: 0??C to +50??C, Wide Temp Range: -20??C to +70??C, Specialized Temp range: -40??C to +80??C

Another note to remember is the LCD Glass and Polarizers are not the only limiting factors in the temperature range of the LCDs. You also need to take into

consideration the temperature limitations of the backlight and controller ICs that may be present along with the LCD.

LCD Module Backlighting

When developing an LCD Module, a backlight can be added to light the LCD and there are several options available to backlight a LCD module. The considerations in backlighting a display are the lighting intensity, life of the backlight, and the power it consumes. Here is a quick comparison of the backlights available.

LED: Offered in both edge and array lit, this technology is preferred due to its variety of colors, intensity, long life (>100K Hrs), wide temperature range, and low voltage requirements. The downsides are the power consumption of some configurations (large sizes), and the uniformity of the lighting for those same configurations.

EL Panel: This backlight is very low power, but it requires a high voltage (120V AC @ 400Hz Typically) and it has a relatively short life (half intensity life \<4K Hrs), and medium temperature range.

Cold Cathode Florescent Lamp: This backlight has a lot of intensity for the power consumed, and has its applications for the larger LCD displays. The downsides are a short life span (\<20K Hrs), vibration will reduce the lifespan of the tube, limited temperature range, and the high voltage it needs to operate (>300V AC @ 30-80KHz). LCD Glare Filter

It is possible to put an anti-reflective filter over the front of a display to improve viewability in harsh lighting conditions. This filter is bonded directly to the front polarizer of the display and its front surface either physically or chemically roughened. This surface re-direct the light waves so that they continue traveling forward instead of reflecting back toward the observer. New anti-reflective materials can reduce the front surface reflections to less than 0.3% or less.

Physical Size

In general, the larger the display, the higher the price. The most expensive part of the Glass or Module LCD in most cases is the glass. Manufacturers usually use a master laminate (Sheet of glass) which is 14" x 16". We can produce a single display that size, or we can partition the array into hundreds of smaller displays . Our strategy is to maximize the number of individual displays which we can get onto this laminate.

We therefore recommend display sizes that give our customers maximum glass utilization.

中文翻译

At present, the market mainstream LCD(liquid crystal display) are divided into the following categories: TN (twisted array type), STN (super twisted array type), DSTN (Double Super Twisted array), HPA (high-performance rapid addressing or DSTN), TFT (thin-film field-effect transistor) and so on.The majority of small household electrical appliances are used in TN-type monochrome liquid crystal displays,Its principle is to have a liquid crystal filled with two out of the plane between the small trough. The two slots on the plane perpendicular to each other (intersection into a 90 °).As the light along the direction of the spread of the arrangement of elements, so when the light through the LCD reversed 90 °. When the liquid crystal when a voltage increase, the vertical elements will be re-arranged so that light can be directed out, without any reverse. This LCD is by two vertical polarization filter constitutes, therefore, under normal circumstances should be to block all attempts to penetrate the light.If the DC-driven LCD, display units will cause permanent damage. In order to prevent irreversible damage to the electrochemical reaction LCD, plus all the characters in the paragraph on the voltage polarity must be reversed periodically so that the paragraph be added to the character of the average voltage is 0. In order to save single-chip I / O port line, using the method of multiplexing drive LCD.

ST7920 LCD controller/driver IC can display alphabets, numbers, Chinese fonts and self-defined characters. It supports 3 kinds of bus interface, namely 8 bit/ 4bit and serial. All functions, including display RAM, character generator ROM, LCD display drivers and control circuits are all in a one-chip solution. With a minimum system configuration, a Chinese character display system can easily achieved.

ST7920 includes character ROM with 8192 16X16 dots Chinese fonts and 126 16X8 dots half height alphanumerical fonts. Also for graphic display it supports

64x256 dots graphic display area（GDRAM）and 240 dots ICON RAM. ST7920 has built in 4 sets CGRAM providing

software programmable 16X16 font. ST7920 has wide operating voltage (2.7V to 5.5V) and low power consumption suitable for battery power portable device.

It is easy to support multi languages application such as Chinese and English. Two consecutive bytes are used to specify one 16x16 character or two 8x16 half-height characters. Character codes are written into DDRAM and the corresponding fonts are mapped from CGROM or HCGROM to the display drivers.

ST7920 provides RAM to support user-defined fonts. These user-defined fonts are displayed the same ways as CGROM fonts through writing character cod data to DDRAM.

液晶显示屏设计指南

以下章节为我们提供了关于液晶玻璃和液晶显示模块的基础知识，这些基础知识对于设计你自己的液晶显示屏或在对液晶显示器生产商提交申请时均大有裨益

液晶显示器产品的分类---液晶显示器玻璃基板或液晶显示模块

设计液晶显示器的最基本步骤是决定显示器是否附加驱动电路(如果有则为液晶显示模块，否则只能为液晶显示玻璃基板)。这两种设计方案选择均有优点和缺点。

客户购买的自定义液晶显示模块，其基本电子线路设计已经有生产商完成。这显而易见节省了设计者大量设计时间，并且减少了至最终产品上市所用到的人力资源。对缩短设计周期的先前研究给了设计者很多宝贵的经验，使其从中获益匪浅，最终带来最佳产品。设计者最重要是要确定接口和所需综合背光器件的类型，众多接口中应用最广泛的是标准串行或并行接口。温度范围，可视角度，取景模式和对比度都是需要考虑的，但是对于业绩显示玻璃基板和液晶显示模块来说这些参数设计是大同小异的。

一块液晶显示器玻璃基板将设计任务交给使用者。为了完成设计任务，设计者需要学习大量关于液晶显示器的知识。幸运的是网站为我们提供了应用信息和网络连接，这些帮助我们查找所需的信息。

购买液晶显示器玻璃基板的最主要原因是减少成本并使设计灵活。制作驱动电路所需组件总成本通常低于预建模块成本，并且如果你的PC板上存在足够的空间，你不需要额外买一块PC板专门为显示器分区，因此也会得到具有成本效益的组装和测试。通过做一点功课，你的设计会和已有模块一样工作，并且为设计者将他们的设计适用于不断变化的需求提供了必须的灵活性。

液晶显示器图像的种类

液晶显示图像包括字符图标，段，图像点阵以及其他任何二者组合。

图标：制作自定义液晶显示器时，你可以在玻璃基板上设置一些特别补充该产品的图像，人们称这些图像为“图标”。这些大致轮廓可以形成任何一种你需要的图像。在液晶显示器上，我们称这些轮廓为一个像素或一个点。

段：液晶显示器的段组成了更大的字符，比如一个七段数字字符段(显示0—9)，或者比如一个14段字母数字字符段(显示数字0—9以及字母A—Z)。

点列阵：这些点列阵几乎涵盖所有规模和网点数。这里有一个例子，字符型

显示器用一系列5*7点阵显示一个字母数字字符的字符串，或者使用一个更大的320*240图形点阵显示可变大小的字母数字字符图像。

液晶种类和技术-TN-STN=FSTN=DSTN-CSTN

这种技术的应用决定于你设计的液晶显示器的具体工作要求。由于不同的方案都可以很好的完成任务，最终成本是必须考虑的。因此在这里我们快速了解一下我们上面提供的技术。

TN：生产成品低，电路耗能少。可视角度不好，对比度一般。染色：灰黑色。静态显示首选，但是在高达32:1的复合率下运行良好。液晶显示器玻璃基板的最爱。

STN：生产成本和功耗中等，平均可视角度，平均对比度。染色：黑绿色或者深蓝灰色。高复合率下工作状态良好。液晶显示模块的最爱，高端液晶显示器玻璃基板的选择。

FSTN：生产成品中等偏上，电路耗能中等偏上。良好的可视角度，完美的对比度。染色：黑白色。高复合率下工作状态良好。高端液晶显示模块的最爱。

阴影：阴影是在显示器画面翻转的影响下形成的，并且只出现在能传送图像的显示器上。这个视觉效果是让背光定义像素打开“打开”(透明)，而“关闭”像素仍然不透明。这种配置在温和且低光照的条件下最佳。

显示方式和偏光片

显示方式是由后置偏光片控制的，就偏光片是否反射光线来说我们将查看方式分为三种。

反射型：这种偏光器的类型在高，中度环境光线下给显示器最亮的显示以及尽可能高的对比度。不幸的是，在夜晚或者光线不断变化的环境中，想要看到显示器上的内容是非常困难的。(想想那些游戏男孩吧)

半透反射型：(最受欢迎的解决方案)如果你设计的液晶显示器必须在广泛的光线变化环境下显示，通常会希望用半透反射显示器，这样在明亮的太阳光下可以轻松读取显示器上内容。

但是在傍晚和夜晚依然会有显示不正常的问题。设计半透反射型显示器的一个折中方法是：当外部光线很足的时候，该液晶显示器按照反射型工作，而当外部光线不足的时候，它又能当作透射型使用。。这样最终你会找到二者之间一个可以接受的方法，然后设计出可接受的显示器。

透射型：这种显示器需要有一个工作背光，除非它从一个窗口类型的设备获得光线。通过它的发光可以照亮位于上方的液晶板，实际就起到一个“光源”的作用。当发光板封装在液晶显示器里后，背光板也许会产生过强的光线。透射式显示屏的优点是能够在昏暗情况下使用户能看到亮度均匀的屏幕，但是在电量消耗

巨大，并不适合能量短缺时的应用，且其需要背光板常亮。请谨记，如果没有背光的激活这种偏光板的选择是不会工作的。

偏光板经常受温度影响，因此当选择一种偏光板时，必须设定偏光板的质量等级。当确定显示器的工作环境温度要求后，你可以确定偏光板的等级。下面给出几种典型的选择。

商业级偏极片：适用于室内或大都数情况下都在室内使用的显示器。这种偏极片在大部分仪器，办公用品，家电产品以及其他远离高温，日照和潮湿的产品中稳定性很好。

工业级偏极片：适用于极端环境，这种偏极片专门为户外显示器设计，尤其适用于极度潮湿环境。我们定义偏极片为工业级

视角

液晶显示器部分的视角定义为垂直于显示器中心的上，下，左，右角度。

6:00方向是从下往上看垂直可视平面具有最佳对比度的视角。(最流行的视角)

12:00方向是从上往下看垂直可视平面具有最佳对比度的视角。

9:00方向是从左往右看垂直可视平面具有最佳对比度的视角，(不常用)

3:00方向是从右向左看垂直可视平面具有最佳对比度的视角。(不常用)

请牢记视角与直接驱动显示器比是次要的。一个基本规则是：复合率越高，视角越重要。同理，如果一个带着偏极片眼镜的人来看你的显示器，你必须在评论部分说明这些，确保一个带着偏极片眼镜的观察者不会困惑。然后你还有谨记，关于报价问题，当你改变主意变化了显示器最终的视角，显示器的价格不应用有大多变化(通常只是上下浮动几美分)

环境主意事项——温度范围

液晶显示器的正常工作温度和存储温度是设计时需要重点考虑的，因为如果液晶显示器工作温度超过或低于正常工作温度范围会使液晶屏不正常工作(当工作在非正常工作温度时)，甚至会永久损害液晶显示器(工作在非正常存储温度下)。液晶显示器的正常工作温度范围由液晶显示器液态晶体，偏极片，工作电压和复合率共同决定。这样出，除去仔细研究这些参数的不同组合，下面有列出了一些基本规则，你可以使用这些规则规定你设计的液晶显示器的正常工作温度范围，之后在你选择恰当的液晶显示器液态晶片，偏极片以及工作电压时液晶显示器生产商可以提供帮助。以下静态值是典型的液晶显示器工作范围。

液晶显示器TN玻璃基板/静态或低复合率时：标准温度范围：-10℃--+60℃，最大温度范围：-40℃--+80℃，专业温度范围：最低工作温度可达-55℃，最高工作温度为+110℃。

液晶显示器TN显示模块/复用时：标准温度范围：0℃--+50℃，最大温度范围：-20℃--+70℃，专业温度范围：最低工作温度可达-40℃，最高工作温度为+90℃。

液晶显示器TN和FSTN显示模块/复用时：标准温度范围：0℃--+50℃，最大温度范围：-20℃--+70℃，专业温度范围：最低工作温度可达-40℃，最高工作温度为+80℃。

还有一点设计者应该注意，确定液晶显示器正常工作范围时，液晶显示器液体晶片和偏极片并不是唯一的限制条件。设计时必须也考虑到可能用到的背光板和控制器IC的正常工作温度范围。

液晶显示模块背光

开发液晶显示模块的过程中，背光板用来给液晶显示模块提供照明，现在有很多可行方法设计液晶显示模块背光板。显示器背光时需要注意一些参数的设置，如照明强度，背光板使用寿命，背光板消耗的功率。下面给出现有的背光板并对他们进行简单的比较。

LED：LED背光板要求在照明区域内具有一定的均匀光通量和照度，所以需要采用阵列。这项技术提供了多种颜色，适宜光通量，并且使用寿命长，正常工作温度范围广，工作电压低，因此广受欢迎。该种板的局限是一些配置(大尺寸)的功率消耗，以及对这些配置照明的一致性。

EL(艾尔)面板：EL板的背光功率很低，但是需要一个很高的电压(典型的是120V AC ，400Hz)，并且EL板的使用寿命相对较短，正常工作温度范围一般。

冷阴极荧光灯泡：这个背光强度功率消耗很大，应用于大型液晶显示器。冷阴极荧光灯泡缺点是使用寿命短，震动减少灯泡的使用寿命，有限的正常工作温度范围以及其正常工作时需要电压过高。(大于300V AC ，30-80KHz)

LCD眩光过滤器

设计者习惯在液晶显示器前置一个防反射滤波器，这样提高了液晶显示器在恶劣照明环境下的可视性。这个防反射滤波器直接和前面的偏极片连接起来，而且该防反射滤波器的前部表面材料的物理特性或者化学特性很粗糙。这个表面使得光波的传播方向没有改变，因此光波可以继续向前传播而不会反射回观察者那方。新型防反射材料已经可以将前表面光波反射率降低到0.3%，甚至更低。

物理尺寸

一般而言，液晶显示器越大，其价格越高。大多数情况下，玻璃基板或者液晶显示模块中最昂贵的部分是玻璃。生产商经常使用一个大小为14“× 16”主层压板(玻璃板材)。我们既可以单独生产这种规格的液晶显示器，也可以将阵列分割成数百的更小的显示器。我们的策略是在这块压层板上最大限度的放置单个显示

器。由此我们推荐给用户的液晶显示器都具有最大的玻璃利用率。