Making A Product People Want – Inspired Concepts in Capacitive Touchscreens Steve
Kolokowsky and Trevor Davis, Cypress Semiconductor 作者：Steve
Kolokowsky ; Trevor Davis
，赛普拉斯半导体
Touchscreen technology has existed for quite a while. Why did it take the iPhone to set the mobile world on fire for touchscreens? The key is in technology inflections. With the market shift from resistive to capacitive touchscreens, the invention of “gesture” motions, and the crystal clear, solid feel of glass screens, touchscreens have once again caught the attention of the worldwide electronics buyer.
触摸屏技术已经存在相当一段时间了。为什么苹果在的iPhone能在手机领域这么火呢？关键是技术革新。它从电阻性触摸屏更新到了电容式触摸屏、首度使用了“手势（gesture）”，采用了更晶莹剔透、更有手感的玻璃屏幕，触摸屏又一次吸引了全世界的电子行业的眼球。
According to a report from iSupply, nearly 400 million touch-screen handsets are expected to ship in 2012.
The technology has been in use in other devices like PDAs for years and had its first major introduction in the United States by Taiwan's HTC, which began selling its HTC Touch in June 2007, just before the iPhone was introduced. But let’s not be mistaken, it was the introduction of the iPhone that has ignited the touchscreen craze in consumer electronics.
Interestingly, the key to the iPhone’s success was very creative use and introduction of four key technology advantages: Capacitive vs. resistive touchscreen, glass vs. plastic coverlens, “edgeless” industrial design, and gesture-based navigation.
Every one of these features was enabled (and will continue to be advanced) because of the technology behind the capacitive touchscreen.
根据iSupply报告，
预计在2012年有近400万触摸屏手机上市。这项技术在其它设备中也已经使用，如PDA已经使用了很多年，首次引入美国的是台湾的宏达（HTC），
在iPhone问世之前，早在2007年6月宏达就开始出售其HTC Touch产品了。但我们不能忽视，正是苹果的引入才使触摸屏在消费电子产品中成为一种时尚。有趣的是,苹果的成功关键是很有创造力地使用和引入了四个关键技术的优势：电容式触摸屏vs.电阻式触摸屏、玻璃覆盖物vs.塑料覆盖物，”edgeless“工业设计，而且基于手势（gesture-based）导航。上述这些特征都能(并将继续提高)使用电容式触摸屏实现。
“Out” with Resistive and “In” with Projected Capacitive
电阻式将落伍，投射电容式（Projected Capacitive）将流行
Perhaps the single most significant technology inflection was the shift from resistive to capacitive touchscreens.
iSupply forecasts that nearly 25% of the mobile handsets with touchscreens will have shifted from resistive to capacitive screens by 2011. In years past, PDA touchscreens had encouraged the use of a stylus for navigation and employed a resistive touch technology.
A resistive touchscreen consists of a flexible top layer, then a layer of ITO (Indium-Tin-Oxide – a conductive, clear metal oxide layer), an air gap and then another layer of ITO.
The panel has 4 wires attached to the ITO layers: one on the left and right sides of the ‘X’ layer, and one on the top and bottom sides of the ‘Y’ layer.
也许最显著的技术改变就是从电阻屏变换到电容屏。iSupply预测，到2011年，近25%的移动电话将由电阻屏幕转移到电容屏。在前些年，掌上电脑PDA触摸屏为了方便使用笔做导航采用了电阻触摸屏技术。电阻触摸屏由下面几部分构成，顶层是塑料薄膜， ITO(Indium-Tin-Oxide -铟锡氧化物)层，空气夹层，然后是又一层ITO。面板有4线连接到ITO，一组在“X”层的左侧和右侧，另一组在“Y”层的上侧和下侧。
FIGURE 1: Resistive Panel with flexible upper layer is being absorbed by Projected Capacitive 图1 电阻触摸屏顶层的薄膜在投射式电容屏中已经不再需要
In a resistive panel, a touch is detected when the flexible top layer is pressed down to contact the lower layer.
The location of a touch is measured in two steps:
First, the ‘X right’ is driven to a known voltage, and the ‘X left’ is driven to ground and the voltage is read from a Y sensor.
This provides the X coordinate.
This process is repeated for the other axis to determine the exact touch position.
在电阻触摸屏中，当按压顶层的薄膜，接触到底层时，就探测到了触摸，触摸位置检测分为下面两个步骤：首先“X右”连接到已知电压，，“X左”连接到地，通过Y sensor读出电压，这就知道了X轴的位置；另外一个轴也采用同样的原理测到位置
There are many well-known problems with resistive systems:
1)
The topmost layer is flexible and feels “squishy” to the touch.
2)
The flexible top layer scratches easily, especially if a stylus is used.
3)
Resistive panels tend to lose sensitivity over time because of the wear of the flexible upper layer and spacer dots
4)
The average clarity of a resistive panel is 75% while a projected capacitive panel is ~90% transmissive.
5)
Resistive touchscreens require periodic calibration to align detected finger position to on-screen icons.
在电阻屏系统中有很多显而易见的问题：
1)顶层的薄膜触摸起来感觉粘粘的。
2)薄膜的表层容易产生划痕，特别是使用触笔的时候。
3)由于顶层薄膜很容易损坏，长时间使用电阻屏将会失去敏感性
4) 电阻屏平均清晰度为75%，而投射电容屏的穿透率约为 90%。
5)电阻式触摸屏需要定期校正，这样才能使检测到的位置和屏幕上的图标一致
Projected capacitance screens, conversely, have no moving parts.
The only thing between the LCD and the user is ITO and glass, which have near 100% optical clarity.
The projected capacitance sensing hardware consists of a glass top layer, followed by an array of X sensors, an insulating layer, then an array of Y sensors on a glass substrate.
Some sensor suppliers create a single-layer sensor that includes both X and Y sensors in a single layer of ITO with small bridges where they cross.
相反，投射电容屏幕没有可活动的部分。LCD和用户之间的唯一就是ITO和玻璃，有接近100%透光度。投射电容感应硬件包含玻璃表层，接着是一组X传感器、一隔热层，然后在玻璃基底上是一组Y传感器。也有一些传感器供应商做出了单层结构，也就是把X和Y放在同一层ITO，成十字交叉结构。
This all-glass touch surface gives the user a solid, smooth feel across the entire screen. Glass screens are preferred by customers because glass gives the end product a smooth industrial design, and provides a good capacitive signal for measuring touch.
全玻璃的接触表面在整个屏幕给用户一个可靠的，光滑的感觉。客户更喜欢玻璃屏是因为玻璃使最终产品设计更容易、更方便工业化，而且为检测触摸提供了一个良好的电容式信号。
Glass – Clear is Sexy
玻璃-清晰就是迷人
Aside from its clear industrial design advantages (pun intended), glass is a superior technology choice for use in touchscreens because of its inherent electrical properties. What most people don’t fully comprehend is that a touchscreen is actually measuring an electrical charge from the user’s finger. In fact, the user changing the capacitance of the system in such a way that the touchscreen controller can measure the touch.
玻璃对于触摸屏来说是很好的选择，因为除了它清澈的工业设计优点（双关)外，还由于其内在的电气性能。大多数人并不完全明白，触摸屏实际上是通过用户的手指测量电荷。事实上，用户用改变了系统电容，在这种情况下触摸屏控制器可以衡量到触摸。
Glass has, from the advent of electricity, been known and used as an insulator, also called a dielectric, which is a material that resists the flow of electric current.
Very often glass has been used to discourage the flow of electricity. However, when used in a capacitive circuit for touchscreens, the use of glass can be quite an advantage.
玻璃的电气特性从出现就被人们所熟知，并作为一种绝缘体(也称为介质)材料来抵抗电流的流动。玻璃经常被用来阻止电荷流动。然而,当用于电容触摸屏时，玻璃的使用是一个很大的优势。
Specifically, in a parallel-plate capacitor, the circuit is composed of two conductive surfaces with an insulator (glass) between them.
The ITO layer is a conductor, a user’s body is a conductor, and the glass is an insulator.
When a user touches the screen, they’ve actually become part of a capacitor.
The touchscreen controller measures this change in capacitance to detect the presense and location of the touch.
具体地说，在平行板电容器中，电路是由两个导电表面与它们之间的绝缘体(玻璃)构成。ITO是导体，用户的身体是导体，玻璃是绝缘体。当用户触摸屏幕时，他们实际上变成了电容器的一部分。触摸屏控制器检测电容的变化来识别触摸的存在以及位置。
The system’s "capacitance" is proportional to the area (A) of one of the plates and inversely proportional to the separation between the plates (d). This relationship is described by: C = e
A / d where e is the permittivity of the insulating material (or dielectric) between the plates.
In a capacitive touchscreen, one plate is the ITO sensor, the other “plate” is your finger!
该系统的“电容”是是和其中一个电容板的面积（A）成正比的，和电容板的距离（d）成反比的。他们之间的关系如下:C =e A / d
，这里e是电容板之间的绝缘材料(或介电)之介电常数。在电容式触摸屏中,一个电容板是ITO，另一个“电容板”就是手指！
Glass and acrylic (plastic) covers are both used today.
Glass has significant sensing advantages over plastic.
Glass has a dielectric constant of 6, while Plexiglas has a dielectric constant of 3.
For comparison, air’s dielectric constant is 1.
Assuming equal thicknesses, a glass cover will provide double the signal strength compared to an acrylic cover.
A stronger signal allows greater sensing accuracy and better tolerance to LCD noise.
现在玻璃和压克力(塑料)覆盖物都经常使用。玻璃比塑料具有明显的传感优势。普通玻璃的介电常数为6，而有机玻璃的介电常数为3。与此相比，空气的介电常数是1。假设相等的厚度，玻璃覆盖物的信号强度是压克力的两倍。信号越强，那么感应越精确，并且更能较好的耐液晶噪声。
Glass has other advantages: it is more scratch-resistant than plastic, it has a consistent surface upon which to deposit ITO, and it can be heated to very high temperatures. This allows ITO to be deposited very uniformly which gives consistent electrical performance.
High temperature is important because ITO changes from a yellowish hue to clear when baked at high temperatures.
玻璃还具有其它的优势：比塑料更抗磨损，它有一致的的表面沉积在ITO，它能耐很高的温度。这使得ITO可以沉积地很均匀从而能得到一致的电气性能。高温是很重要的，因为在高温下烧制，ITO会从淡黄色变的透明。
In addition to physical changes to the touchscreen, the technology of the touchscreen also ushered in a new wave of software interaction on mobile devices.
除了触摸屏的物理变化，触摸屏技术还迎来了手机软件的新一波互动。
Innovations in User Experience (UX) – The Gesture Revolution
用户界面（UX）的重大变革-手势革命
Perhaps the most significant User Experience or “UX” change that was made has been the move from the menu-based touch products of the past to the finger-navigation based on icons and graphics. Previously, the touchscreen relied on a stylus.
Today, however, capacitive touchscreens can accurately predict finger center to 0.5mm.
With this level of accuracy, a stylus is no longer needed and completely new interface techniques can be developed.
也许最重要的用户界面或“UX“变化就是把原来的基于菜单式触摸的产品变成了基于手指导航的图标和图形化产品。在这以前，触摸要依靠触笔实现。然而今天，电容式触摸屏能测量手指中心准确到0.5毫米。由于能达到这样的精确水平，因此开发了这种完全不需要触笔的全新接口技术。
One of the most significant steps beyond icon-based navigation was the invention of the “gesture”.
Today, gestures are known simply as a “swipe”, “pan”, “pinch” or “zoom”, and others. These are simply ways to take a combination of finger activity on a touchscreen and to convert them into meaningful, organic, movement on the screen. Until the implementation of capacitive touchscreens, however, gestures were not possible due to the slow response time of other designs.
Projected capacitance touchscreens combine high resolution with high-speed sensing.
This powerful combination opens up new User Experience possibilities.
一个最重要的步骤就是
“手势（gesture）”的发明，这超越了图标导航方式。现在, 手势一般简单的认为包括 “敲击” 、“平移”、“缩小”或“放大”等等。这些都是手指在触摸屏上能做出的简单有效的组合，并且转化成屏幕上的有意义的、有机的运动。在电容式触摸屏实现之前，手势是不可能实现的，因为其它设计方案响应时间比较慢。投射电容触摸屏结合了高分辨率和高速感应特点。可以说，正是这两种特性，才使新的人机界面成为可能。
Figure 2. User Interface revolutionized by “Gestures” enabled by X/Y tracking and multi-touch
Once people become used to gestures, they will demand more.
The exciting thing about gestures is that they don’t have to be related to the current application.
Imagine adjusting the volume of your music player player while you’re in another application.
So far, gestures have replaced the scroll wheel on your mouse by adding scroll and zoom functions.
The next step will be “always on” global gestures that work like the multimedia keys on your laptop.
One gesture immediately opens your phone application, another moves to the next song in your playlist.
一旦人们习惯使用手势，他们会要求更多。关于手势一个令人高兴的事就是是他们不会关系到当前的应用。想象一下，当你使用媒体播放器时，你在进行某种操作，这时候又需要调节音量，那么你完全可以进行音量调节而不用退出当前应用程序。到目前为止,手势已经取代了鼠标上的滚轮，增加了触摸滚动、变焦功能。下一步将是“永远在线“球形手势，就像是在你的笔记本电脑上的多媒体键。一种手势即刻打开了你的电话功能，另一个却移动到你的播放目录里的下一首歌。
The next generation of touch devices will be enabled through the capability of “multitouch” or “All Points”. This is the ability to recognize an unlimited number of touches on a screen. Being able to determine exactly where each touch occurs allows for intelligent design of algorithms that can reject false finger touches (fingers wrapped around a phone), complicated gestures (three or four finger gestures for unique features), palm rejection (phone “on” and “off” on pickup), and so on. In fact, new innovations in the touchscreen ecosystem will continue to enable the market.
下一代的触摸设备会具备“多点触摸”或者“识别位置”。这就是说可以识别屏幕上的多个点。由于有智能设计算法，能够准确地确定每个接触的发生，可以避免错误的手指触动(手指在电话上滑动)、可以识别复杂的手势(三、四个手指实现一个手势)、避免手掌误触(拿放电话时“开“或“关”)等等。事实上，触摸屏领域的创新将继续使这个市场更有活力。
Innovations on the Way – New Touchscreen Capability
创新之路-最新触摸屏技术
Windows 7 is set to be released this fall with more gesture-recognition built directly into the operating system.
Windows Mobile 7 is reportedly not too far behind. It is expected that more PC makers are planning to take advantage of the new touch capabilities in Windows 7. While touch-screen PC products are not yet wildly popular, there haven't been many consumer-friendly touchscreen notebooks yet, and the draw for software applications employing touch has been low. But that will change soon. Recently Sony said it plans to release a touchscreen Vaio notebook this fall, and Hewlett-Packard and Asus have already released products earlier this year.
去年秋天发布的Windows 7将更多的手势识别直接嵌入了操作系统。据报道， Windows Mobile 7也紧随其后。预计更多的PC制造商正计划利用Windows 7中新的触摸功能。现在触摸屏的个人电脑产品还没有很流行，还没有很好用的触摸电脑，触摸应用软件还比较差。但这些情况很快就会改变。最近索尼公司说他们计划推出触摸笔记本Vaio，惠普公司和华硕已经在早些时候发布他们的产品。
Last year, according to IDC, just 1 percent of the notebook market, or 1.4 million units, were touch-screen notebooks. With the wave of new Netbooks (screens ~10”) coming to market, it is expected that this level of penetration of touchscreens will change.
One of the key contributors will be changes in price for larger screen projected capacitance products. As the ecosystem of touch software continues to build, so will consumer demand for other advanced features.
据IDC去年报道，只有1%的笔记本市场，或者说140万台是触摸屏笔记本。随着新的笔记本（10寸屏幕）的上市，可以预见，触摸屏电脑所占比例将会改变。其关键因素之一就是，大尺寸投射电容触摸屏产品的价格会有变化。触摸软件系统将不断创新，可以根据客户需求设计更多功能。
Significant capabilities for capacitive touch will continue to be developed in the areas of water rejection, using a passive (or untethered or non-powered) stylus, handwriting and Kanji recognition, and hover or near-touch capabilities (growing a button or icon before it is depressed).
电容式触摸许多重要功能也会继续开发，例如防水功能，使用无源 (或untethered或无供电)触笔、手写、汉字识别，盘旋或接近触摸能力（在按下按钮或图标之前，它就已经感知)。
So while the world marvels at the success of the iPhone and other new touch-based competitive products, there are few people who really understand the technology behind the success. Without advancements in touchscreen technology, today’s successful touch-based phones would likely be yet another modestly successful stylus-based resistive touch phone.
Instead, with of the conversion from resistive to capacitive touchscreens, the invention of “gesture” motions, and the crystal clear, solid feel of glass screens, touchscreens have set the consumer marketplace on fire for touch – will your next product take advantage of this movement?
所以,当整个世界都在惊叹于iPhone和其他有竞争力的触摸产品时，只有一小部分人真正了解成功背后的技术本身。假如没有触摸屏技术的发展，今天触摸屏手机的成功还仅仅是基于触笔的电阻式触摸的成功。当电容式触摸屏取代了电阻式触摸屏后，有了革命性的“手势”、更透亮、更结实的玻璃屏,触摸屏已经在消费品市场很流行-你的新产品会有触摸屏吗?
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